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1. The methane imperative

Author

Shindell, D., Sadavarte, P., Aben, I., de Oliveira Bredariol, T., Dreyfus, G., Höglund-Isaksson, L., Poulter, B., Saunois, M., Schmidt, G.A., Szopa, S., Rentz, K., Parsons, L., Qu, Z., Faluvegi, G., Maasakkers, J.D., Shindell, D., Sadavarte, P., Aben, I., de Oliveira Bredariol, T., Dreyfus, G., Höglund-Isaksson, L., Poulter, B., Saunois, M., Schmidt, G.A., Szopa, S., Rentz, K., Parsons, L., Qu, Z., Faluvegi, G., and Maasakkers, J.D.

Abstract

Anthropogenic methane (CH4) emissions increases from the period 1850–1900 until 2019 are responsible for around 65% as much warming as carbon dioxide (CO2) has caused to date, and large reductions in methane emissions are required to limit global warming to 1.5°C or 2°C. However, methane emissions have been increasing rapidly since ~2006. This study shows that emissions are expected to continue to increase over the remainder of the 2020s if no greater action is taken and that increases in atmospheric methane are thus far outpacing projected growth rates. This increase has important implications for reaching net zero CO2 targets: every 50 Mt CH4 of the sustained large cuts envisioned under low-warming scenarios that are not realized would eliminate about 150 Gt of the remaining CO2 budget. Targeted methane reductions are therefore a critical component alongside decarbonization to minimize global warming. We describe additional linkages between methane mitigation options and CO2, especially via land use, as well as their respective climate impacts and associated metrics. We explain why a net zero target specifically for methane is neither necessary nor plausible. Analyses show where reductions are most feasible at the national and sectoral levels given limited resources, for example, to meet the Global Methane Pledge target, but they also reveal large uncertainties. Despite these uncertainties, many mitigation costs are clearly low relative to real-world financial instruments and very low compared with methane damage estimates, but legally binding regulations and methane pricing are needed to meet climate goals.

Published
2024
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2. A perspective on the next generation of Earth system model scenarios: towards representative emission pathways (REPs)

Author

Meinshausen, M., Schleussner, C.-F., Beyer, K., Bodeker, G., Boucher, O., Canadell, J.G., Daniel, J.S., Diongue-Niang, A., Driouech, F., Fischer, E., Forster, P., Grose, M., Hansen, G., Hausfather, Z., Ilyina, T., Kikstra, J., Kimutai, J., King, A.D., Lee, J.-Y., Lennard, C., Lissner, T., Nauels, A., Peters, G.P., Pirani, A., Plattner, G.-K., Pörtner, H., Rogelj, J., Rojas, M., Roy, J., Samset, B.H., Sanderson, B.M., Séférian, R., Seneviratne, S., Smith, C., Szopa, S., Thomas, A., Urge-Vorsatz, D., Velders, G.J.M., Yokohata, T., Ziehn, T., Nicholls, Z., Meinshausen, M., Schleussner, C.-F., Beyer, K., Bodeker, G., Boucher, O., Canadell, J.G., Daniel, J.S., Diongue-Niang, A., Driouech, F., Fischer, E., Forster, P., Grose, M., Hansen, G., Hausfather, Z., Ilyina, T., Kikstra, J., Kimutai, J., King, A.D., Lee, J.-Y., Lennard, C., Lissner, T., Nauels, A., Peters, G.P., Pirani, A., Plattner, G.-K., Pörtner, H., Rogelj, J., Rojas, M., Roy, J., Samset, B.H., Sanderson, B.M., Séférian, R., Seneviratne, S., Smith, C., Szopa, S., Thomas, A., Urge-Vorsatz, D., Velders, G.J.M., Yokohata, T., Ziehn, T., and Nicholls, Z.

Published
2024

3. A perspective on the next generation of Earth system model scenarios: towards representative emission pathways (REPs)

Author

Meinshausen, M, Schleussner, C-F, Beyer, K, Bodeker, G, Boucher, O, Canadell, JG, Daniel, JS, Diongue-Niang, A, Driouech, F, Fischer, E, Forster, P, Grose, M, Hansen, G, Hausfather, Z, Ilyina, T, Kikstra, JS, Kimutai, J, King, AD, Lee, J-Y, Lennard, C, Lissner, T, Nauels, A, Peters, GP, Pirani, A, Plattner, G-K, Poertner, H, Rogelj, J, Rojas, M, Roy, J, Samset, BH, Sanderson, BM, Seferian, R, Seneviratne, S, Smith, CJ, Szopa, S, Thomas, A, Urge-Vorsatz, D, Velders, GJM, Yokohata, T, Ziehn, T, Nicholls, Z, Meinshausen, M, Schleussner, C-F, Beyer, K, Bodeker, G, Boucher, O, Canadell, JG, Daniel, JS, Diongue-Niang, A, Driouech, F, Fischer, E, Forster, P, Grose, M, Hansen, G, Hausfather, Z, Ilyina, T, Kikstra, JS, Kimutai, J, King, AD, Lee, J-Y, Lennard, C, Lissner, T, Nauels, A, Peters, GP, Pirani, A, Plattner, G-K, Poertner, H, Rogelj, J, Rojas, M, Roy, J, Samset, BH, Sanderson, BM, Seferian, R, Seneviratne, S, Smith, CJ, Szopa, S, Thomas, A, Urge-Vorsatz, D, Velders, GJM, Yokohata, T, Ziehn, T, and Nicholls, Z

Abstract

In every Intergovernmental Panel on Climate Change (IPCC) Assessment cycle, a multitude of scenarios are assessed, with different scope and emphasis throughout the various Working Group reports and special reports, as well as their respective chapters. Within the reports, the ambition is to integrate knowledge on possible climate futures across the Working Groups and scientific research domains based on a small set of “framing pathways” such as the so-called representative concentration pathways (RCPs) in the Fifth IPCC Assessment Report (AR5) and the shared socioeconomic pathway (SSP) scenarios in the Sixth Assessment Report (AR6). This perspective, initiated by discussions at the IPCC Bangkok workshop in April 2023 on the “Use of Scenarios in AR6 and Subsequent Assessments”, is intended to serve as one of the community contributions to highlight the needs for the next generation of framing pathways that is being advanced under the Coupled Model Intercomparison Project (CMIP) umbrella, which will influence or even predicate the IPCC AR7 consideration of framing pathways. Here we suggest several policy research objectives that such a set of framing pathways should ideally fulfil, including mitigation needs for meeting the Paris Agreement objectives, the risks associated with carbon removal strategies, the consequences of delay in enacting that mitigation, guidance for adaptation needs, loss and damage, and for achieving mitigation in the wider context of societal development goals. Based on this context, we suggest that the next generation of climate scenarios for Earth system models should evolve towards representative emission pathways (REPs) and suggest key categories for such pathways. These framing pathways should address the most critical mitigation policy and adaptation plans that need to be implemented over the next 10 years. In our view, the most important categories are those relevant in the context of the Paris Agreement long-term goal, specific

Published
2024

4. Indicators of Global Climate Change 2023: annual update of key indicators of the state of the climate system and human influence

Author

Forster, P. M., Smith, C., Walsh, T., Lamb, W., Lamboll, R., Hall, B., Hauser, M., Ribes, A., Rosen, D., Gillett, N., Palmer, M. D., Rogelj, J., von Schuckmann, K., Trewin, B., Allen, M., Andrew, R., Betts, R., Boyer, T., Buontempo, C., Burgess, S., Cagnazzo, C., Cheng, L., Friedlingstein, P., Gettelman, A., Gütschow, J., Ishii, M., Jenkins, S., Lan, X., Morice, C., Mühle, J., Kadow, C., Kennedy, J., Killick, R., Krummel, P. B., Minx, J. C., Myhre, G., Naik, V., Peters, G. P., Pirani, A., Pongratz, J., Schleussner, C.-F., Seneviratne, S. I., Szopa, S., Thorne, P., Kovilakam, M. V. M., Majamäki, E., Jalkanen, J.-P., van Marle, M., Hoesly, R. M., Rohde, R., Schumacher, D., van der Werf, G., Vose, R., Zickfeld, K., Zhang, X., Masson-Delmotte, V., Zhai, P., Forster, P. M., Smith, C., Walsh, T., Lamb, W., Lamboll, R., Hall, B., Hauser, M., Ribes, A., Rosen, D., Gillett, N., Palmer, M. D., Rogelj, J., von Schuckmann, K., Trewin, B., Allen, M., Andrew, R., Betts, R., Boyer, T., Buontempo, C., Burgess, S., Cagnazzo, C., Cheng, L., Friedlingstein, P., Gettelman, A., Gütschow, J., Ishii, M., Jenkins, S., Lan, X., Morice, C., Mühle, J., Kadow, C., Kennedy, J., Killick, R., Krummel, P. B., Minx, J. C., Myhre, G., Naik, V., Peters, G. P., Pirani, A., Pongratz, J., Schleussner, C.-F., Seneviratne, S. I., Szopa, S., Thorne, P., Kovilakam, M. V. M., Majamäki, E., Jalkanen, J.-P., van Marle, M., Hoesly, R. M., Rohde, R., Schumacher, D., van der Werf, G., Vose, R., Zickfeld, K., Zhang, X., Masson-Delmotte, V., and Zhai, P.

Abstract

Intergovernmental Panel on Climate Change (IPCC) assessments are the trusted source of scientific evidence for climate negotiations taking place under the United Nations Framework Convention on Climate Change (UNFCCC). Evidence-based decision-making needs to be informed by up-to-date and timely information on key indicators of the state of the climate system and of the human influence on the global climate system. However, successive IPCC reports are published at intervals of 5–10 years, creating potential for an information gap between report cycles. We follow methods as close as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One (WGI) report. We compile monitoring datasets to produce estimates for key climate indicators related to forcing of the climate system: emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. The purpose of this effort, grounded in an open data, open science approach, is to make annually updated reliable global climate indicators available in the public domain (https://doi.org/10.5281/zenodo.11064126, Smith et al., 2024a). As they are traceable to IPCC report methods, they can be trusted by all parties involved in UNFCCC negotiations and help convey wider understanding of the latest knowledge of the climate system and its direction of travel. The indicators show that, for the 2014–2023 decade average, observed warming was 1.19 [1.06 to 1.30] °C, of which 1.19 [1.0 to 1.4] °C was human-induced. For the single year average, human-induced warming reached 1.31 [1.1 to 1.7] °C in 2023 relative to 1850–1900. This is below the 2023 observed record of 1.43 [1.32 to 1.53] °C, indicating a substantial contribution of internal variability in the 2023 record. Human-induced warming has been incr

Published
2024

5. Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

Author

Naik, V, Voulgarakis, A, Fiore, AM, Horowitz, LW, Lamarque, JF, Lin, M, Prather, MJ, Young, PJ, Bergmann, D, Cameron-Smith, PJ, Cionni, I, Collins, WJ, Dalsøren, SB, Doherty, R, Eyring, V, Faluvegi, G, Folberth, GA, Josse, B, Lee, YH, MacKenzie, IA, Nagashima, T, Van Noije, TPC, Plummer, DA, Righi, M, Rumbold, ST, Skeie, R, Shindell, DT, Stevenson, DS, Strode, S, Sudo, K, Szopa, S, and Zeng, G

Abstract

We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multi-model mean OH concentration is overestimated by 5 to 10% but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north-south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34%). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7% to an increase of 14.6%) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the change in global mean tropospheric CO and NOx burdens (ΔCO/ΔNOx, approximately represents changes in OH sinks versus changes in OH sources) in the models, pointing to a need for better constraints on natural precursor emissions and on the chemical mechanisms in the current generation of chemistry-climate models. For the 1980 to 2000 period, we find that climate warming and a slight increase in mean OH (3.5 ± 2.2%) leads to a 4.3 ± 1.9% decrease in the methane lifetime. Analysing sensitivity simulations performed by 10 models, we find that preindustrial to present-day climate change decreased the methane lifetime by about four months, representing a negative feedback on the climate system. Further, we analysed attribution experiments performed by a subset of models relative to 2000 conditions with only one precursor at a time set to 1860 levels. We find that global mean OH increased by 46.4 ± 12.2% in response to preindustrial to present-day anthropogenic NOx emission increases, and decreased by 17.3 ± 2.3%, 7.6 ± 1.5%, and 3.1 ± 3.0% due to methane burden, and anthropogenic CO, and NMVOC emissions increases, respectively. © Author(s) 2013.

Published
2013

6. Three decades of global methane sources and sinks

Author

Kirschke, S, Bousquet, P, Ciais, P, Saunois, M, Canadell, JG, Dlugokencky, EJ, Bergamaschi, P, Bergmann, D, Blake, DR, Bruhwiler, L, Cameron-Smith, P, Castaldi, S, Chevallier, F, Feng, L, Fraser, A, Heimann, M, Hodson, EL, Houweling, S, Josse, B, Fraser, PJ, Krummel, PB, Lamarque, JF, Langenfelds, RL, Le Quéré, C, Naik, V, O'doherty, S, Palmer, PI, Pison, I, Plummer, D, Poulter, B, Prinn, RG, Rigby, M, Ringeval, B, Santini, M, Schmidt, M, Shindell, DT, Simpson, IJ, Spahni, R, Steele, LP, Strode, SA, Sudo, K, Szopa, S, Van Der Werf, GR, Voulgarakis, A, Van Weele, M, Weiss, RF, Williams, JE, and Zeng, G

Subjects
Meteorology & Atmospheric Sciences
Abstract

Methane is an important greenhouse gas, responsible for about 20% of the warming induced by long-lived greenhouse gases since pre-industrial times. By reacting with hydroxyl radicals, methane reduces the oxidizing capacity of the atmosphere and generates ozone in the troposphere. Although most sources and sinks of methane have been identified, their relative contributions to atmospheric methane levels are highly uncertain. As such, the factors responsible for the observed stabilization of atmospheric methane levels in the early 2000s, and the renewed rise after 2006, remain unclear. Here, we construct decadal budgets for methane sources and sinks between 1980 and 2010, using a combination of atmospheric measurements and results from chemical transport models, ecosystem models, climate chemistry models and inventories of anthropogenic emissions. The resultant budgets suggest that data-driven approaches and ecosystem models overestimate total natural emissions. We build three contrasting emission scenarios-which differ in fossil fuel and microbial emissions-to explain the decadal variability in atmospheric methane levels detected, here and in previous studies, since 1985. Although uncertainties in emission trends do not allow definitive conclusions to be drawn, we show that the observed stabilization of methane levels between 1999 and 2006 can potentially be explained by decreasing-to-stable fossil fuel emissions, combined with stable-to-increasing microbial emissions. We show that a rise in natural wetland emissions and fossil fuel emissions probably accounts for the renewed increase in global methane levels after 2006, although the relative contribution of these two sources remains uncertain. © 2013 Macmillan Publishers Limited.

Published
2013

7. Analysis of present day and future OH and methane lifetime in the ACCMIP simulations

Author

Voulgarakis, A., Naik, V., Lamarque, J.-F., Shindell, D. T, Young, P. J, Prather, M. J, Wild, O., Field, R. D, Bergmann, D., Cameron-Smith, P., Cionni, I., Collins, W. J, Dalsøren, S. B, Doherty, R. M, Eyring, V., Faluvegi, G., Folberth, G. A, Horowitz, L. W, Josse, B., MacKenzie, I. A, Nagashima, T., Plummer, D. A, Righi, M., Rumbold, S. T, Stevenson, D. S, Strode, S. A, Sudo, K., Szopa, S., and Zeng, G.

Subjects
atmospheric chemistry, climate change, climate modeling, hydroxyl radical, methane, photolysis, radiative forcing, stratosphere, troposphere
Abstract

Results from simulations performed for the Atmospheric Chemistry and Climate Modeling Intercomparison Project (ACCMIP) are analysed to examine how OH and methane lifetime may change from present day to the future, under different climate and emissions scenarios. Present day (2000) mean tropospheric chemical lifetime derived from the ACCMIP multi-model mean is 9.8 ± 1.6 yr (9.3 ± 0.9 yr when only including selected models), lower than a recent observationally-based estimate, but with a similar range to previous multi-model estimates. Future model projections are based on the four Representative Concentration Pathways (RCPs), and the results also exhibit a large range. Decreases in global methane lifetime of 4.5 ± 9.1% are simulated for the scenario with lowest radiative forcing by 2100 (RCP 2.6), while increases of 8.5 ± 10.4% are simulated for the scenario with highest radiative forcing (RCP 8.5). In this scenario, the key driver of the evolution of OH and methane lifetime is methane itself, since its concentration more than doubles by 2100 and it consumes much of the OH that exists in the troposphere. Stratospheric ozone recovery, which drives tropospheric OH decreases through photolysis modifications, also plays a partial role. In the other scenarios, where methane changes are less drastic, the interplay between various competing drivers leads to smaller and more diverse OH and methane lifetime responses, which are difficult to attribute. For all scenarios, regional OH changes are even more variable, with the most robust feature being the large decreases over the remote oceans in RCP8.5. Through a regression analysis, we suggest that differences in emissions of non-methane volatile organic compounds and in the simulation of photolysis rates may be the main factors causing the differences in simulated present day OH and methane lifetime. Diversity in predicted changes between present day and future OH was found to be associated more strongly with differences in modelled temperature and stratospheric ozone changes. Finally, through perturbation experiments we calculated an OH feedback factor (F) of 1.24 from present day conditions (1.50 from 2100 RCP8.5 conditions) and a climate feedback on methane lifetime of 0.33 ± 0.13 yr K−1, on average. Models that did not include interactive stratospheric ozone effects on photolysis showed a stronger sensitivity to climate, as they did not account for negative effects of climate-driven stratospheric ozone recovery on tropospheric OH, which would have partly offset the overall OH/methane lifetime response to climate change.

Published
2013

8. Future impact of traffic emissions on atmospheric ozone and OH based on two scenarios

Author

Hodnebrog, O., Berntsen, T. K, Dessens, O., Gauss, M., Grewe, V., Isaksen, I. S. A, Koffi, B., Myhre, G., Olivie, D., Prather, M. J, Stordal, F., Szopa, S., Tang, Q., van Velthoven, P., and Williams, J. E

Abstract

The future impact of traffic emissions on atmospheric ozone and OH has been investigated separately for the three sectors AIRcraft, maritime SHIPping and ROAD traffic. To reduce uncertainties we present results from an ensemble of six different atmospheric chemistry models, each simulating the atmospheric chemical composition in a possible high emission scenario (A1B), and with emissions from each transport sector reduced by 5% to estimate sensitivities. Our results are compared with optimistic future emission scenarios (B1 and B1 ACARE), presented in a companion paper, and with the recent past (year 2000). Present-day activity indicates that anthropogenic emissions so far evolve closer to A1B than the B1 scenario. As a response to expected changes in emissions, AIR and SHIP will have increased impacts on atmospheric O3 and OH in the future while the impact of ROAD traffic will decrease substantially as a result of technological improvements. In 2050, maximum aircraft-induced O3 occurs near 80° N in the UTLS region and could reach 9 ppbv in the zonal mean during summer. Emissions from ship traffic have their largest O3 impact in the maritime boundary layer with a maximum of 6 ppbv over the North Atlantic Ocean during summer in 2050. The O3 impact of road traffic emissions in the lower troposphere peaks at 3 ppbv over the Arabian Peninsula, much lower than the impact in 2000. Radiative forcing (RF) calculations show that the net effect of AIR, SHIP and ROAD combined will change from a marginal cooling of −0.44 ± 13 mW m−2 in 2000 to a relatively strong cooling of −32 ± 9.3 (B1) or −32 ± 18 mW m−2 (A1B) in 2050, when taking into account RF due to changes in O3, CH4 and CH4-induced O3. This is caused both by the enhanced negative net RF from SHIP, which will change from −19 ± 5.3 mW m−2 in 2000 to −31 ± 4.8 (B1) or −40 ± 9 mW m−2 (A1B) in 2050, and from reduced O3 warming from ROAD, which is likely to turn from a positive net RF of 12 ± 8.5 mW m−2 in 2000 to a slightly negative net RF of −3.1 ± 2.2 (B1) or −3.1 ± 3.4 (A1B) mW m−2 in the middle of this century. The negative net RF from ROAD is temporary and induced by the strong decline in ROAD emissions prior to 2050, which only affects the methane cooling term due to the longer lifetime of CH4 compared to O3. The O3 RF from AIR in 2050 is strongly dependent on scenario and ranges from 19 ± 6.8 (B1 ACARE) to 61 ± 14 mW m−2 (A1B). There is also a considerable span in the net RF from AIR in 2050, ranging from −0.54 ± 4.6 (B1 ACARE) to 12 ± 11 (A1B) mW m−2 compared to 6.6 ± 2.2 mW m−2 in 2000.

Published
2012

9. Future impact of non-land based traffic emissions on atmospheric ozone and OH - an optimistic scenario and a possible mitigation strategy

Author

Hodnebrog, O., Berntsen, T. K, Dessens, O., Gauss, M., Grewe, V., Isaksen, I. S. A, Koffi, B., Myhre, G., Olivie, D., Prather, M. J, Pyle, J. A, Stordal, F., Szopa, S., Tang, Q., van Velthoven, P., Williams, J. E, and Odemark, K.

Subjects
atmospheric chemistry, atmospheric modeling, boundary layer, chemical composition, ozone, radiative forcing, traffic emission
Abstract

The impact of future emissions from aviation and shipping on the atmospheric chemical composition has been estimated using an ensemble of six different atmospheric chemistry models. This study considers an optimistic emission scenario (B1) taking into account e.g. rapid introduction of clean and resource-efficient technologies, and a mitigation option for the aircraft sector (B1 ACARE), assuming further technological improvements. Results from sensitivity simulations, where emissions from each of the transport sectors were reduced by 5%, show that emissions from both aircraft and shipping will have a larger impact on atmospheric ozone and OH in near future (2025; B1) and for longer time horizons (2050; B1) compared to recent time (2000). However, the ozone and OH impact from aircraft can be reduced substantially in 2050 if the technological improvements considered in the B1 ACARE will be achieved. Shipping emissions have the largest impact in the marine boundary layer and their ozone contribution may exceed 4 ppbv (when scaling the response of the 5% emission perturbation to 100% by applying a factor 20) over the North Atlantic Ocean in the future (2050; B1) during northern summer (July). In the zonal mean, ship-induced ozone relative to the background levels may exceed 12% near the surface. Corresponding numbers for OH are 6.0 × 105 molecules cm−3 and 30%, respectively. This large impact on OH from shipping leads to a relative methane lifetime reduction of 3.92 (±0.48) on the global average in 2050 B1 (ensemble mean CH4 lifetime is 8.0 (±1.0) yr), compared to 3.68 (±0.47)% in 2000. Aircraft emissions have about 4 times higher ozone enhancement efficiency (ozone molecules enhanced relative to NOx molecules emitted) than shipping emissions, and the maximum impact is found in the UTLS region. Zonal mean aircraft-induced ozone could reach up to 5 ppbv at northern mid- and high latitudes during future summer (July 2050; B1), while the relative impact peaks during northern winter (January) with a contribution of 4.2%. Although the aviation-induced impact on OH is lower than for shipping, it still causes a reduction in the relative methane lifetime of 1.68 (±0.38)% in 2050 B1. However, for B1 ACARE the perturbation is reduced to 1.17 (±0.28)%, which is lower than the year 2000 estimate of 1.30 (±0.30)%. Based on the fully scaled perturbations we calculate net radiative forcings from the six models taking into account ozone, methane (including stratospheric water vapour), and methane-induced ozone changes. For the B1 scenario, shipping leads to a net cooling with radiative forcings of −28.0 (±5.1) and −30.8 (±4.8) mW m−2 in 2025 and 2050, respectively, due to the large impact on OH and, thereby, methane lifetime reductions. Corresponding values for the aviation sector shows a net warming effect with 3.8 (±6.1) and 1.9 (±6.3) mW m−2, respectively, but with a small net cooling of -0.6 (±4.6) mW m−2 for B1 ACARE in 2050.

Published
2011

10. Radiative forcing due to changes in ozone and methane caused by the transport sector

Author

Myhre, G., Shine, K.P., Radel, G., Gauss, M., Isaksen, I.S.A., Tang, Q., Prather, M.J., Williams, J.E., van Velthoven, P., Dessens, O., Koffi, B., Szopa, S., Hoor, P., Grewe, V., Borken-Kleefeld, J., Berntsen, T.K., and Fuglestvedt, J.S.

Subjects
aircraft models, atmospheric chemistry, atmospheric movements, aviation, carbon monoxide, global warming, methane, nitrogen, ozone, roads and streets, ships
Abstract

The year 2000 radiative forcing (RF) due to changes in O3 and CH4 (and the CH4-induced stratospheric water vapour) as a result of emissions of short-lived gases (oxides of nitrogen (NOx), carbon monoxide and non-methane hydrocarbons) from three transport sectors (ROAD, maritime SHIPping and AIRcraft) are calculated using results from five global atmospheric chemistry models. Using results from these models plus other published data, we quantify the uncertainties. The RF due to short-term O3 changes (i.e. as an immediate response to the emissions without allowing for the long-term CH4 changes) is positive and highest for ROAD transport (31 mW m−2) compared to SHIP (24 mW m−2) and AIR (17 mW m−2) sectors in four of the models. All five models calculate negative RF from the CH4 perturbations, with a larger impact from the SHIP sector than for ROAD and AIR. The net RF of O3 and CH4 combined (i.e. including the impact of CH4 on ozone and stratospheric water vapour) is positive for ROAD (+16(±13) (one standard deviation) mW m−2) and AIR (+6(±5) mW m−2) traffic sectors and is negative for SHIP (−18(±10) mW m−2) sector in all five models. Global Warming Potentials (GWP) and Global Temperature change Potentials (GTP) are presented for AIR NOxemissions; there is a wide spread in the results from the 5 chemistry models, and it is shown that differences in the methane response relative to the O3 response drive much of the spread.

Published
2011

11. A multi-model study of the hemispheric transport and deposition of oxidised nitrogen

Author

Sanderson, M. G, Dentener, F. J, Fiore, A. M, Cuvelier, C., Keating, T. J, Zuber, A., Atherton, C. S, Bergmann, D. J, Diehl, T., Doherty, R. M, Duncan, B. N, Hess, P., Horowitz, L. W, Jacob, D. J, Jonson, J.-E., Kaminski, J. W, Lupu, A., MacKenzie, I. A, Mancini, E., Marmer, E., Park, R., Pitari, G., Prather, M. J, Pringle, K. J, Schroeder, S., Schultz, M. G, Shindell, D. T, Szopa, S., Wild, O., and Wind, P.

Subjects
atmospheric deposition, atmospheric transport, emission, nitric oxide, nitrogen, pollutant transport
Abstract

Fifteen chemistry-transport models are used to quantify, for the first time, the export of oxidised nitrogen (NOy) to and from four regions (Europe, North America, South Asia, and East Asia), and to estimate the uncertainty in the results. Between 12 and 24% of the NOx emitted is exported from each region annually. The strongest impact of each source region on a foreign region is: Europe on East Asia, North America on Europe, South Asia on East Asia, and East Asia on North America. Europe exports the most NOy, and East Asia the least. East Asia receives the most NOy from the other regions. Between 8 and 15% of NOx emitted in each region is transported over distances larger than 1000 km, with 3–10% ultimately deposited over the foreign regions.

Published
2008

12. Multimodel simulations of carbon monoxide: Comparison with observations and projected near-future changes

Author

Shindell, D. T, Faluvegi, G., Stevenson, D. S, Krol, M. C, Emmons, L. K, Lamarque, J.-F., Pétron, G., Dentener, F. J, Ellingsen, K., Schultz, M. G, Wild, O., Amann, M., Atherton, C. S, Bergmann, D. J, Bey, I., Butler, T., Cofala, J., Collins, W. J, Derwent, R. G, Doherty, R. M, Drevet, J., Eskes, H. J, Fiore, A. M, Gauss, M., Hauglustaine, D. A, Horowitz, L. W, Isaksen, I. S. A, Lawrence, M. G, Montanaro, V., Müller, J.-F., Pitari, G., Prather, M. J, Pyle, J. A, Rast, S., Rodriguez, J. M, Sanderson, M. G, Savage, N. H, Strahan, S. E, Sudo, K., Szopa, S., Unger, N., van Noije, T. P. C, and Zeng, G.

Subjects
air quality, atmospheric chemistry, atmospheric pollution, biomass burning, carbon monoxide, climate change, hydrocarbon, hydroxyl radical, Northern Hemisphere, observational method, satellite imagery, simulation, volatile organic compound
Abstract

We analyze present-day and future carbon monoxide (CO) simulations in 26 state-of-the-art atmospheric chemistry models run to study future air quality and climate change. In comparison with near-global satellite observations from the MOPITT instrument and local surface measurements, the models show large underestimates of Northern Hemisphere (NH) extratropical CO, while typically performing reasonably well elsewhere. The results suggest that year-round emissions, probably from fossil fuel burning in east Asia and seasonal biomass burning emissions in south-central Africa, are greatly underestimated in current inventories such as IIASA and EDGAR3.2. Variability among models is large, likely resulting primarily from intermodel differences in representations and emissions of nonmethane volatile organic compounds (NMVOCs) and in hydrologic cycles, which affect OH and soluble hydrocarbon intermediates. Global mean projections of the 2030 CO response to emissions changes are quite robust. Global mean midtropospheric (500 hPa) CO increases by 12.6 ± 3.5 ppbv (16%) for the high-emissions (A2) scenario, by 1.7 ± 1.8 ppbv (2%) for the midrange (CLE) scenario, and decreases by 8.1 ± 2.3 ppbv (11%) for the low-emissions (MFR) scenario. Projected 2030 climate changes decrease global 500 hPa CO by 1.4 ± 1.4 ppbv. Local changes can be much larger. In response to climate change, substantial effects are seen in the tropics, but intermodel variability is quite large. The regional CO responses to emissions changes are robust across models, however. These range from decreases of 10–20 ppbv over much of the industrialized NH for the CLE scenario to CO increases worldwide and year-round under A2, with the largest changes over central Africa (20–30 ppbv), southern Brazil (20–35 ppbv) and south and east Asia (30–70 ppbv). The trajectory of future emissions thus has the potential to profoundly affect air quality over most of the world's populated areas.

Published
2006

13. Multi-model ensemble simulations of tropospheric NO2 compared with GOME retrievals for the year 2000

Author

van Noije, T. P. C, Eskes, H. J, Dentener, F. J, Stevenson, D. S, Ellingsen, K., Schultz, M. G, Wild, O., Amann, M., Atherton, C. S, Bergmann, D. J, Bey, I., Boersma, K. F, Butler, T., Cofala, J., Drevet, J., Fiore, A. M, Gauss, M., Hauglustaine, D. A, Horowitz, L. W, Isaksen, I. S. A, Krol, M. C, Lamarque, J.-F., Lawrence, M. G, Martin, R. V, Montanaro, V., Muller, J.-F., Pitari, G., Prather, M. J, Pyle, J. A, Richter, A., Rodriguez, J. M, Savage, N. H, Strahan, S. E, Sudo, K., Szopa, S., and van Roozendael, M.

Subjects
anthropogenic source, biomass burning, comparative study, ERS-2, GOME, nitrous oxide, sampling bias, timescale, troposphere
Abstract

We present a systematic comparison of tropospheric NO2 from 17 global atmospheric chemistry models with three state-of-the-art retrievals from the Global Ozone Monitoring Experiment (GOME) for the year 2000. The models used constant anthropogenic emissions from IIASA/EDGAR3.2 and monthly emissions from biomass burning based on the 1997–2002 average carbon emissions from the Global Fire Emissions Database (GFED). Model output is analyzed at 10:30 local time, close to the overpass time of the ERS-2 satellite, and collocated with the measurements to account for sampling biases due to incomplete spatiotemporal coverage of the instrument. We assessed the importance of different contributions to the sampling bias: correlations on seasonal time scale give rise to a positive bias of 30–50% in the retrieved annual means over regions dominated by emissions from biomass burning. Over the industrial regions of the eastern United States, Europe and eastern China the retrieved annual means have a negative bias with significant contributions (between –25% and +10% of the NO2 column) resulting from correlations on time scales from a day to a month. We present global maps of modeled and retrieved annual mean NO2 column densities, together with the corresponding ensemble means and standard deviations for models and retrievals. The spatial correlation between the individual models and retrievals are high, typically in the range 0.81–0.93 after smoothing the data to a common resolution. On average the models underestimate the retrievals in industrial regions, especially over eastern China and over the Highveld region of South Africa, and overestimate the retrievals in regions dominated by biomass burning during the dry season. The discrepancy over South America south of the Amazon disappears when we use the GFED emissions specific to the year 2000. The seasonal cycle is analyzed in detail for eight different continental regions. Over regions dominated by biomass burning, the timing of the seasonal cycle is generally well reproduced by the models. However, over Central Africa south of the Equator the models peak one to two months earlier than the retrievals. We further evaluate a recent proposal to reduce the NOx emission factors for savanna fires by 40% and find that this leads to an improvement of the amplitude of the seasonal cycle over the biomass burning regions of Northern and Central Africa. In these regions the models tend to underestimate the retrievals during the wet season, suggesting that the soil emissions are higher than assumed in the models. In general, the discrepancies between models and retrievals cannot be explained by a priori profile assumptions made in the retrievals, neither by diurnal variations in anthropogenic emissions, which lead to a marginal reduction of the NO2 abundance at 10:30 local time (by 2.5–4.1% over Europe). Overall, there are significant differences among the various models and, in particular, among the three retrievals. The discrepancies among the retrievals (10–50% in the annual mean over polluted regions) indicate that the previously estimated retrieval uncertainties have a large systematic component. Our findings imply that top-down estimations of NOx emissions from satellite retrievals of tropospheric NO2 are strongly dependent on the choice of model and retrieval.

Published
2006

14. Multimodel ensemble simulations of present-day and near-future tropospheric ozone

Author

Stevenson, DS, Dentener, FJ, Schultz, MG, Ellingsen, K, van Noije, TPC, Wild, O, Zeng, G, Amann, M, Atherton, CS, Bell, N, Bergmann, DJ, Bey, I, Butler, T, Cofala, J, Collins, WJ, Derwent, RG, Doherty, RM, Drevet, J, Eskes, HJ, Fiore, AM, Gauss, M, Hauglustaine, DA, Horowitz, LW, Isaksen, ISA, Krol, MC, Lamarque, JF, Lawrence, MG, Montanaro, V, Müller, JF, Pitari, G, Prather, MJ, Pyle, JA, Rast, S, Rodriquez, JM, Sanderson, MG, Savage, NH, Shindell, DT, Strahan, SE, Sudo, K, and Szopa, S

Subjects
Meteorology & Atmospheric Sciences
Abstract

Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state-of-the-art atmospheric chemistry models have been intercompared and synthesized as part of a wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing "optimistic," "likely," and "pessimistic" options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5% decrease, through a 6% increase, to a 15% increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25%. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of -50, 180, and 300 mW m-2, compared to a CO2 forcing over the same time period of 800-1100 mW m-2. These values indicate the importance of air pollution emissions in short- to medium-term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere-troposphere exchange. This level of climate change also reduces the methane lifetime by around 4%. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000 and 550 Tg(O3) yr-1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O3)) is 10% larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10% shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NOx production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere-troposphere exchange; biomass burning; and water vapor concentrations. Copyright 2006 by the American Geophysical Union.

Published
2006

15. Radiative forcing since preindustrial times due to ozone change in the troposphere and the lower stratosphere

Author

Gauss, M., Myhre, G., Isaksen, I. S. A, Grewe, V., Pitari, G., Wild, O., Collins, W. J, Dentener, F. J, Ellingsen, K., Gohar, L. K, Hauglustaine, D. A, Iachetti, D., Lamarque, F., Mancini, E., Mickley, L. J, Prather, M. J, Pyle, J. A, Sanderson, M. G, Shine, K. P, Stevenson, D. S, Sudo, K., Szopa, S., and Zeng, G.

Subjects
anthropogenic source, climate change, ozone, radiative forcing, stratosphere, troposphere
Abstract

Changes in atmospheric ozone have occurred since the preindustrial era as a result of increasing anthropogenic emissions. Within ACCENT, a European Network of Excellence, ozone changes between 1850 and 2000 are assessed for the troposphere and the lower stratosphere (up to 30 km) by a variety of seven chemistry-climate models and three chemical transport models. The modeled ozone changes are taken as input for detailed calculations of radiative forcing.When only changes in chemistry are considered (constant climate) the modeled global-mean tropospheric ozone column increase since preindustrial times ranges from 7.9 DU to 13.8 DU among the ten participating models, while the stratospheric column reduction lies between 14.1 DU and 28.6 DU in the models considering stratospheric chemistry. The resulting radiative forcing is strongly dependent on the location and altitude of the modeled ozone change and varies between 0.25 Wm−2 and 0.45 Wm−2 due to ozone change in the troposphere and −0.123 Wm−2 and +0.066 Wm−2 due to the stratospheric ozone change.Changes in ozone and other greenhouse gases since preindustrial times have altered climate. Six out of the ten participating models have performed an additional calculation taking into account both chemical and climate change. In most models the isolated effect of climate change is an enhancement of the tropospheric ozone column increase, while the stratospheric reduction becomes slightly less severe. In the three climate-chemistry models with detailed tropospheric and stratospheric chemistry the inclusion of climate change increases the resulting radiative forcing due to tropospheric ozone change by up to 0.10 Wm−2, while the radiative forcing due to stratospheric ozone change is reduced by up to 0.034 Wm−2.Considering tropospheric and stratospheric change combined, the total ozone column change is negative while the resulting net radiative forcing is positive.

Published
2006

16. Indicators of Global Climate Change 2022: annual update of large-scale indicators of the state of the climate system and human influence

Author

Forster, P.M., Smith, C.J., Walsh, T., Lamb, W.F., Lamboll, R., Hauser, M., Ribes, A., Rosen, D., Gillett, N., Palmer, M.D., Rogelj, J., von Schuckmann, K., Seneviratne, S.I., Trewin, B., Zhang, X., Allen, M., Andrew, R., Birt, A., Borger, A., Boyer, T., Broersma, J.A., Cheng, L., Dentener, F., Friedlingstein, P., Gutiérrez, J.M., Gütschow, J., Hall, B., Ishii, M., Jenkins, S., Lan, X., Lee, J., Morice, C., Kadow, C., Kennedy, J., Killick, R., Minx, J.C., Naik, V., Peters, G.P., Pirani, A., Pongratz, J., Schleussner, C.F., Szopa, S., Thorne, P., Rohde, R., Rojas Corradi, M., Schumacher, D., Vose, R., Zickfeld, K., Masson-Delmotte, V., Zhai, P., Forster, P.M., Smith, C.J., Walsh, T., Lamb, W.F., Lamboll, R., Hauser, M., Ribes, A., Rosen, D., Gillett, N., Palmer, M.D., Rogelj, J., von Schuckmann, K., Seneviratne, S.I., Trewin, B., Zhang, X., Allen, M., Andrew, R., Birt, A., Borger, A., Boyer, T., Broersma, J.A., Cheng, L., Dentener, F., Friedlingstein, P., Gutiérrez, J.M., Gütschow, J., Hall, B., Ishii, M., Jenkins, S., Lan, X., Lee, J., Morice, C., Kadow, C., Kennedy, J., Killick, R., Minx, J.C., Naik, V., Peters, G.P., Pirani, A., Pongratz, J., Schleussner, C.F., Szopa, S., Thorne, P., Rohde, R., Rojas Corradi, M., Schumacher, D., Vose, R., Zickfeld, K., Masson-Delmotte, V., and Zhai, P.

Abstract

Intergovernmental Panel on Climate Change (IPCC) assessments are the trusted source of scientific evidence for climate negotiations taking place under the United Nations Framework Convention on Climate Change (UNFCCC), including the first global stocktake under the Paris Agreement that will conclude at COP28 in December 2023. Evidence-based decision-making needs to be informed by up-to-date and timely information on key indicators of the state of the climate system and of the human influence on the global climate system. However, successive IPCC reports are published at intervals of 5–10 years, creating potential for an information gap between report cycles. We follow methods as close as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One (WGI) report. We compile monitoring datasets to produce estimates for key climate indicators related to forcing of the climate system: emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, surface temperature changes, the Earth's energy imbalance, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. The purpose of this effort, grounded in an open data, open science approach, is to make annually updated reliable global climate indicators available in the public domain (https://doi.org/10.5281/zenodo.8000192, Smith et al., 2023a). As they are traceable to IPCC report methods, they can be trusted by all parties involved in UNFCCC negotiations and help convey wider understanding of the latest knowledge of the climate system and its direction of travel. The indicators show that human-induced warming reached 1.14 [0.9 to 1.4] ∘C averaged over the 2013–2022 decade and 1.26 [1.0 to 1.6] ∘C in 2022. Over the 2013–2022 period, human-induced warming has been increasing at an unprecedented rate of over 0.2 ∘C per decade. This high rate of warming is caused by a combination of greenhouse gas emi

Published
2023
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17. A perspective on the next generation of Earth system model scenarios: towards representative emission pathways (REPs)

Author

Meinshausen, M., Schleussner, C.-F., Beyer, K., Bodeker, G., Boucher, O., Canadell, J.G., Daniel, J.S., Diongue-Niang, A., Driouech, F., Fischer, E., Forster, P., Grose, M., Hansen, G., Hausfather, Z., Ilyina, T., Kikstra, J., Kimutai, J., King, A., Lee, J.-Y., Lennard, C., Lissner, T., Nauels, A., Peters, G.P., Pirani, A., Plattner, G.-K., Pörtner, H., Rogelj, J., Rojas, M., Roy, J., Samset, B.H., Sanderson, B.M., Séférian, R., Seneviratne, S., Smith, C., Szopa, S., Thomas, A., Urge-Vorsatz, D., Velders, G.J.M., Yokohata, T., Ziehn, T., Nicholls, Z., Meinshausen, M., Schleussner, C.-F., Beyer, K., Bodeker, G., Boucher, O., Canadell, J.G., Daniel, J.S., Diongue-Niang, A., Driouech, F., Fischer, E., Forster, P., Grose, M., Hansen, G., Hausfather, Z., Ilyina, T., Kikstra, J., Kimutai, J., King, A., Lee, J.-Y., Lennard, C., Lissner, T., Nauels, A., Peters, G.P., Pirani, A., Plattner, G.-K., Pörtner, H., Rogelj, J., Rojas, M., Roy, J., Samset, B.H., Sanderson, B.M., Séférian, R., Seneviratne, S., Smith, C., Szopa, S., Thomas, A., Urge-Vorsatz, D., Velders, G.J.M., Yokohata, T., Ziehn, T., and Nicholls, Z.

Abstract

In every IPCC Assessment cycle, a multitude of scenarios are assessed, with different scope and emphasis throughout the various Working Group and Special Reports and their respective chapters. Within the reports, the ambition is to integrate knowledge on possible climate futures across the Working Groups and scientific research domains based on a small set of ‘framing pathways’, such as the so-called RCP pathways from the Fifth IPCC Assessment report (AR5) and the SSP-RCP scenarios in the Sixth Assessment Report (AR6). This perspective, initiated by discussions at the IPCC Bangkok workshop in April 2023 on the “Use of Scenarios in AR6 and Subsequent Assessments”, is intended to serve as one of the community contributions to highlight needs for the next generation of framing pathways that is being advanced under the CMIP umbrella for use in the IPCC AR7. Here we suggest a number of policy research objectives that such a set of framing pathways should ideally fulfil, including mitigation needs for meeting the Paris Agreement objectives, the risks associated with carbon removal strategies, the consequences of delay in enacting that mitigation, guidance for adaptation needs, loss and damage, and for achieving mitigation in the wider context of Societal Development goals. Based on this context we suggest that the next generation of climate scenarios for Earth System Models should evolve towards ‘Representative Emission Pathways’ (REPs) and suggest key categories for such pathways. These ‘framing pathways’ should address the most critical mitigation policy and adaptation needs over the next 5–10 years. In our view the most important categories are those relevant in the context of the Paris Agreement long-term goal, specifically an immediate action (low overshoot) 1.5 °C pathway, and a delayed action (high overshoot) 1.5 °C pathway. Two other key categories are a pathway category approximately in line with current (as expressed by 2023) near- and long-term policy objective

Published
2023
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19. Ability of the global models to reproduce UT/LS large scale features of CO, CH4, CO2 and oxygenated compounds assessed by comparisons with the airborne CARIBIC data

Author

Alkemade, F., Szopa, S., van Velthoven, P., Zahn, A., Schuck, T., Brenninkmeijer, C., Laboratoire des Sciences du Climat et de l'Environnement (LSCE), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; Due to the lack of observations, the budgets of key chemical species in the upper troposphere/lower stratosphere region are still highly uncertain. Hence, the large scale gradient of CO/CO2/CH4 or the abundance and feature of oxygenated compounds are poorly captured by the global chemistry-transport models. The CARIBIC project relies on the use of a passenger aircraft for making frequent atmospheric chemistry measurements mainly in the tropopause region. It provides accurate and simultaneous observations of several compounds in the upper troposphere/lower stratosphere. These airborne observations, nowadays covering several years, are used in this work to evaluate the ability of two global models (TM5 and LMDz-INCA) to simulate the seasonal variations, inter-hemispheric differences and vertical distributions of CH4, CO and CO2 in this region. Furthermore, as CARIBIC provides original measurements of oxygenated compounds, the distribution and budget of such compounds which control the radical production in the UTLS, is also investigated. This work is performed in the framework of the GEOmon EU project.

Published
2023

20. The CNRM-CM5.1 global climate model: description and basic evaluation

Author

Voldoire, A., Sanchez-Gomez, E., Salas y Mélia, D., Decharme, B., Cassou, C., Sénési, S., Valcke, S., Beau, I., Alias, A., Chevallier, M., Déqué, M., Deshayes, J., Douville, H., Fernandez, E., Madec, G., Maisonnave, E., Moine, M.-P., Planton, S., Saint-Martin, D., Szopa, S., Tyteca, S., Alkama, R., Belamari, S., Braun, A., Coquart, L., and Chauvin, F.

Published
2013
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21. Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

Author

Dufresne, J.-L., Foujols, M.-A., Denvil, S., Caubel, A., Marti, O., Aumont, O., Balkanski, Y., Bekki, S., Bellenger, H., Benshila, R., Bony, S., Bopp, L., Braconnot, P., Brockmann, P., Cadule, P., Cheruy, F., Codron, F., Cozic, A., Cugnet, D., de Noblet, N., Duvel, J.-P., Ethé, C., Fairhead, L., Fichefet, T., Flavoni, S., Friedlingstein, P., Grandpeix, J.-Y., Guez, L., Guilyardi, E., Hauglustaine, D., Hourdin, F., Idelkadi, A., Ghattas, J., Joussaume, S., Kageyama, M., Krinner, G., Labetoulle, S., Lahellec, A., Lefebvre, M.-P., Lefevre, F., Levy, C., Li, Z. X., Lloyd, J., Lott, F., Madec, G., Mancip, M., Marchand, M., Masson, S., Meurdesoif, Y., Mignot, J., Musat, I., Parouty, S., Polcher, J., Rio, C., Schulz, M., Swingedouw, D., Szopa, S., Talandier, C., Terray, P., Viovy, N., and Vuichard, N.

Published
2013
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23. Short-Lived Climate Forcers (Chapter 6)

Author

Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S.L., Péan, C., Berger, S., Caud, N., Chen, Y., Goldfarb, L., Gomis, M.I, Huang, M., Leitzell, K., Lonnoy, E., Matthews, J.B.R., Maycock, T.K., Waterfield, T., Yelekçi, K., Yu, R., Zhu, B., Szopa, S., Naik, V., Adhikary, B., Artaxo, P., Berntsen, T., Collins, W.D., Fuzzi, S., Gallardo, L., Kiendler-Scharr, A., Klimont, Z., Liao, H., Unger, N., Zanis, P., Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S.L., Péan, C., Berger, S., Caud, N., Chen, Y., Goldfarb, L., Gomis, M.I, Huang, M., Leitzell, K., Lonnoy, E., Matthews, J.B.R., Maycock, T.K., Waterfield, T., Yelekçi, K., Yu, R., Zhu, B., Szopa, S., Naik, V., Adhikary, B., Artaxo, P., Berntsen, T., Collins, W.D., Fuzzi, S., Gallardo, L., Kiendler-Scharr, A., Klimont, Z., Liao, H., Unger, N., and Zanis, P.

Abstract

Short-lived climate forcers (SLCFs) affect climate and are, in most cases, also air pollutants. They include aerosols (sulphate, nitrate, ammonium, carbonaceous aerosols, mineral dust and sea spray), which are also called particulate matter (PM), and chemically reactive gases (methane, ozone, some halogenated compounds, nitrogen oxides, carbon monoxide, non-methane volatile organic compounds, sulphur dioxide and ammonia). Except for methane and some halogenated compounds whose lifetimes are about a decade or more, SLCF abundances are spatially highly heterogeneous since they only persist in the atmosphere from a few hours to a couple of months. SLCFs are either radiatively active or influence the abundances of radiatively active compounds through chemistry (chemical adjustments), and their climate effect occurs predominantly in the first two decades after their emission or formation. They can have either a cooling or warming effect on climate, and they also affect precipitation and other climate variables. Methane and some halogenated compounds are included in climate treaties, unlike the other SLCFs that are nevertheless indirectly affected by climate change mitigation since many of them are often co-emitted with CO2 in combustion processes. This chapter assesses the changes, in the past and in a selection of possible futures, of the emissions and abundances of individual SLCFs primarily on global to continental scales, and how these changes affect the Earth’s energy balance through radiative forcing and feedback in the climate system. The attribution of climate and air-quality changes to emissions sectors and regions, and the effects of SLCF mitigations defined for various environmental purposes, are also assessed.

Published
2021

25. Long-term Ozone Changes and Associated Climate Impacts in CMIP5 Simulations

Author

Eyring, V, Arblaster, J. M, Cionni, I, Sedlacek, J, Perlwitz, J, Young, P. J, Bekki, S, Bergmann, D, Cameron-Smith, P, Collins, W. J, Faluvegi, G, Gottschaldt, K.-D, Horowitz, L. W, Kinnison, D. E, Lamarque, J.-F, Marsh, D. R, Saint-Martin, D, Shindell, D. T, Sudo, K, Szopa, S, and Watanabe, S

Subjects
Meteorology And Climatology
Abstract

Ozone changes and associated climate impacts in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations are analyzed over the historical (1960-2005) and future (2006-2100) period under four Representative Concentration Pathways (RCP). In contrast to CMIP3, where half of the models prescribed constant stratospheric ozone, CMIP5 models all consider past ozone depletion and future ozone recovery. Multimodel mean climatologies and long-term changes in total and tropospheric column ozone calculated from CMIP5 models with either interactive or prescribed ozone are in reasonable agreement with observations. However, some large deviations from observations exist for individual models with interactive chemistry, and these models are excluded in the projections. Stratospheric ozone projections forced with a single halogen, but four greenhouse gas (GHG) scenarios show largest differences in the northern midlatitudes and in the Arctic in spring (approximately 20 and 40 Dobson units (DU) by 2100, respectively). By 2050, these differences are much smaller and negligible over Antarctica in austral spring. Differences in future tropospheric column ozone are mainly caused by differences in methane concentrations and stratospheric input, leading to approximately 10DU increases compared to 2000 in RCP 8.5. Large variations in stratospheric ozone particularly in CMIP5 models with interactive chemistry drive correspondingly large variations in lower stratospheric temperature trends. The results also illustrate that future Southern Hemisphere summertime circulation changes are controlled by both the ozone recovery rate and the rate of GHG increases, emphasizing the importance of simulating and taking into account ozone forcings when examining future climate projections.

Published
2013
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26. A 4-D Climatology (1979-2009) of the Monthly Tropospheric Aerosol Optical Depth Distribution over the Mediterranean Region from a Comparative Evaluation and Blending of Remote Sensing and Model Products

Author

Nabat, P, Somot, S, Mallet, M, Chiapello, I, Morcrette, J. J, Solomon, F, Szopa, S, Dulac, F, Collins, W, Ghan, S, Horowitz, L. W, Lamarque, J. F, Lee, Y. H, Naik, V, Nagashima, T, Shindell, D, and Skeie, R

Subjects
Meteorology And Climatology, Earth Resources And Remote Sensing
Abstract

Since the 1980s several spaceborne sensors have been used to retrieve the aerosol optical depth (AOD) over the Mediterranean region. In parallel, AOD climatologies coming from different numerical model simulations are now also available, permitting to distinguish the contribution of several aerosol types to the total AOD. In this work, we perform a comparative analysis of this unique multiyear database in terms of total AOD and of its apportionment by the five main aerosol types (soil dust, seasalt, sulfate, black and organic carbon). We use 9 different satellite-derived monthly AOD products: NOAA/AVHRR, SeaWiFS (2 products), TERRA/MISR, TERRA/MODIS, AQUA/MODIS, ENVISAT/MERIS, PARASOL/POLDER and MSG/SEVIRI, as well as 3 more historical datasets: NIMBUS7/CZCS, TOMS (onboard NIMBUS7 and Earth- Probe) and METEOSAT/MVIRI. Monthly model datasets include the aerosol climatology from Tegen et al. (1997), the climate-chemistry models LMDz-OR-INCA and RegCM-4, the multi-model mean coming from the ACCMIP exercise, and the reanalyses GEMS and MACC. Ground-based Level- 2 AERONET AOD observations from 47 stations around the basin are used here to evaluate the model and satellite data. The sensor MODIS (on AQUA and TERRA) has the best average AOD scores over this region, showing a relevant spatio-temporal variability and highlighting high dust loads over Northern Africa and the sea (spring and summer), and sulfate aerosols over continental Europe (summer). The comparison also shows limitations of certain datasets (especially MERIS and SeaWiFS standard products). Models reproduce the main patterns of the AOD variability over the basin. The MACC reanalysis is the closest to AERONET data, but appears to underestimate dust over Northern Africa, where RegCM-4 is found closer to MODIS thanks to its interactive scheme for dust emissions. The vertical dimension is also investigated using the CALIOP instrument. This study confirms differences of vertical distribution between dust aerosols showing a large vertical spread, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003-2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology.We extend the 2003-2009 reconstruction to the past up to 1979 using the 2003-2009 average and applying the decreasing trend in sulfate aerosols from LMDz-OR-INCA, whose AOD trends over Europe and the Mediterranean are median among the ACCMIP models. Finally optical properties of the different aerosol types in this region are proposed from Mie calculations so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosol-climate studies.

Published
2013
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27. Tropospheric Ozone Changes, Radiative Forcing and Attribution to Emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

Author

Stevenson, D.S, Young, P.J, Naik, V, Lamarque, J.-F, Shindell, D. T, Voulgarakis, A, Skeie, R. B, Dalsoren, S. B, Myhre, G, Berntsen, T. K, Folberth, G. A, Rumbold, S. T, Collins, W. J, MacKenzie, I. A, Doherty, R. M, Zeng, G, vanNoije, T. P. C, Strunk, A, Bergmann, D, Cameron-Smith, P, Plummer, D. A, Strode, S. A, Horowitz, L, Lee, Y. H, Szopa, S, Sudo, K, Nagashima, T, Josse, B, Cionni, I, Righi, M, Eyring, V, Conley, A, Bowman, K. W, Wild, O, and Archibald, A

Subjects
Meteorology And Climatology
Abstract

Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (+/-1 standard deviation) in RFs of +/-17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of +/-10 percent. Applying two different tropopause definitions gives differences in RFs of +/-3 percent. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of +/-30 percent for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44+/-12 percent), nitrogen oxides (31 +/- 9 percent), carbon monoxide (15 +/- 3 percent) and non-methane volatile organic compounds (9 +/- 2 percent); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m(−2) DU(−1), a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m(−2); relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.

Published
2013
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28. Science and Exploration in the Solar Power Sail OKEANOS Mission to a Jupiter Trojan Asteroid

Author

Okada, T., Iwata, T., Matsumoto, J., Chujo, Toshihiro, Kebukawa, Y., Aoki, J., Kawai, Y., Yokota, S., Saito, Y., Terada, K., Toyoda, M., Ito, M., Yabuta, H., Yurimoto, H., Okamoto, C., Matsuura, S., Tsumura, K., Yoneyoku, D., Mihara, T., Matsuoka, A., Nomura, R., Yano, H., Hirai, T., Nakamura, R., Ulamec, S., Jaumann, R., Bibring, J. P., Grand, N., Szopa, S., Palomba, E., Helbert, J., Herique, A., Grott, M., Auster, H. U., Klingelhöfer, G., Saiki, T., Kato, H, Mori, O., and Kawaguchi, J.

Subjects
Planetengeologie, Planetenphysik, Mass spectrometry, OKEANOS, solar power sail, lander, Jupiter trojans, Nutzerzentrum für Weltraumexperimente (MUSC), Solar System Formations
Abstract

The SPS-OKEANOS (Outsized Kitecraft for Exploration and AstroNautics in the Outer Solar system) is under study in Japan to rendezvous with and land on a Jupiter Trojan asteroid [1]. It is primarily an engineering mission to demonstrate advanced space technology but also to conduct key science for understanding the solar system origin and evolution by conducting indepth measurements there. The concept is complementary to LUCY [2], multi-flybys to six Jupiter Trojans, that was selected as a Discovery class mission, aiming at understanding the variation and diversity of Jupiter Trojans. The SPS-OKEANOS mission is jointly studied between engineers and scientists both from Japan and Europe [3]. The scientific objectives and the strawman payloads for this mission are described here

Published
2018

29. European atmosphere in 2050, a regional air quality and climate perspective under CMIP5 scenarios

Author

Colette, A., Bessagnet, B., Vautard, R., Szopa, S., Rao, S., Schucht, S., Klimont, Z., Menut, L., Clain, G., Meleux, F., Curci, Gabriele, Rouïl, L, ., Institut National de l'Environnement Industriel et des Risques (INERIS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), International Institute for Applied Systems Analysis [Laxenburg] (IIASA), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation du climat (CLIM), Équipe Troposphère, SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Università degli Studi dell'Aquila (UNIVAQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, and Civs, Gestionnaire

Subjects
[SDE] Environmental Sciences, NEAR-SURFACE OZONE, Atmospheric Science, Meteorology, 010504 meteorology & atmospheric sciences, TROPOSPHERIC OZONE, [SDE.MCG]Environmental Sciences/Global Changes, Climate commitment, Climate change, 010501 environmental sciences, 7. Clean energy, 01 natural sciences, lcsh:Chemistry, PARTICULATE MATTER, INTERCOMPARISON PROJECT ACCMIP, GENERAL-CIRCULATION MODEL, NEAR-SURFACE OZONE, TROPOSPHERIC OZONE, PARTICULATE MATTER, POLLUTION LEVELS, TRANSPORT MODEL, NORTH-AMERICA, LEVEL OZONE, SIMULATIONS, 11. Sustainability, GENERAL-CIRCULATION MODEL, LEVEL OZONE, Air quality index, 0105 earth and related environmental sciences, [SDE.IE]Environmental Sciences/Environmental Engineering, Global warming, Representative Concentration Pathways, NORTH-AMERICA, SIMULATIONS, lcsh:QC1-999, POLLUTION LEVELS, lcsh:QD1-999, 13. Climate action, Climatology, TRANSPORT MODEL, [SDE]Environmental Sciences, Climate sensitivity, Environmental science, Climate model, INTERCOMPARISON PROJECT ACCMIP, lcsh:Physics, Downscaling
Abstract

To quantify changes in air pollution over Europe at the 2050 horizon, we designed a comprehensive modelling system that captures the external factors considered to be most relevant, and that relies on up-to-date and consistent sets of air pollution and climate policy scenarios. Global and regional climate as well as global chemistry simulations are based on the recent representative concentration pathways (RCP) produced for the Fifth Assessment Report (AR5) of the IPCC (Intergovernmental Panel on Climate Change) whereas regional air quality modelling is based on the updated emissions scenarios produced in the framework of the Global Energy Assessment. We explored two diverse scenarios: a reference scenario where climate policies are absent and a mitigation scenario which limits global temperature rise to within 2 °C by the end of this century. This first assessment of projected air quality and climate at the regional scale based on CMIP5 (5th Coupled Model Intercomparison Project) climate simulations is in line with the existing literature using CMIP3. The discrepancy between air quality simulations obtained with a climate model or with meteorological reanalyses is pointed out. Sensitivity simulations show that the main factor driving future air quality projections is air pollutant emissions, rather than climate change or intercontinental transport of pollution. Whereas the well documented "climate penalty" that weights upon ozone (increase of ozone pollution with global warming) over Europe is confirmed, other features appear less robust compared to the literature, such as the impact of climate on PM2.5. The quantitative disentangling of external factors shows that, while several published studies focused on the climate penalty bearing upon ozone, the contribution of the global ozone burden is somewhat overlooked in the literature.

Published
2013
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31. Impact of future land-cover changes on HNO3 and O3 surface dry deposition

Author

Verbeke, T., Lathière, J., Szopa, S., de Noblet-Ducoudré, N., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:Chemistry, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], lcsh:QD1-999, lcsh:Physics, lcsh:QC1-999
Abstract

Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between the present day (2006) and the future (2050) on dry deposition velocities at the surface, with special interest for ozone (O3) and nitric acid (HNO3), two compounds which are characterized by very different physicochemical properties. The 3-D chemistry-transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections, RCPs 2.6, 4.5 and 8.5, and present-day (2007) meteorology. The 2050 RCP 8.5 vegetation distribution leads to a rise of up to 7 % (+0.02 cm s−1) in the surface deposition velocity calculated for ozone (Vd,O3) and a decrease of −0.06 cm s−1 in the surface deposition velocity calculated for nitric acid (Vd,HNO3) relative to the present-day values in tropical Africa and up to +18 and −15 %, respectively, in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land-cover change in Eurasia, Vd,HNO3 increases by up to 20 % (annual-mean value) and reduces Vd,O3 by the same magnitude in this region. When analyzing the impact of surface dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual-mean surface ozone concentration for both the RCP 8.5 and RCP 2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally by up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario also induces an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the Northern Hemisphere during winter, especially in Eurasia, by +50 % (+0.07 cm s−1) for Vd,O3 and +100 % (+0.9 cm s−1) for Vd,HNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be significant and to differ strongly from one scenario to another. It should therefore be considered in biosphere–atmospheric chemistry interaction studies in order to have a fully consistent picture.

Published
2015
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32. Moving towards ambitious climate policies: monetised health benefits from improved air quality could offset mitigation costs in Europe

Author

Schucht, S., Colette, A., Rao, S., Holland, M., Schöpp, W., Kolp, P., Klimont, Z., Bessagnet, B., Szopa, S., Vautard, R., Brignon, J.-M., Rouil, L., Schucht, S., Colette, A., Rao, S., Holland, M., Schöpp, W., Kolp, P., Klimont, Z., Bessagnet, B., Szopa, S., Vautard, R., Brignon, J.-M., and Rouil, L.

Abstract

Air quality and related health effects are not only affected by policies directly addressed at air pollution but also by other environmental strategies such as climate mitigation. This study addresses how different climate policy pathways indirectly bear upon air pollution in terms of improved human health in Europe. To this end, we put in perspective mitigation costs and monetised health benefits of reducing PM2.5 (particles less than 2.5 mm in diameter) and ozone concentraions. Air quality in Europe and related health impacts were assessed using a comprehensive modelling chain, based on global and regional climate and chemistry-transport models together with a health impact assessment tool. This allows capturing both the impact of climate policy on emissions of air pollutants and the geophysical impact of climate change on air quality. Results are presented for projections at the 2050 horizon, for a set of consistent air pollution and climate policy scenarios, combined with population data from the UN's World Population Prospects, and are expressed in terms of morbidity and mortality impacts of PM2.5 and ozone pollution and their monetised damage equivalent. The analysis shows that enforcement of current European air quality policies would effectively reduce health impacts from PM2.5 in Europe even in the absence of climate policies (life years lost from the exposure to PM2.5 decrease by 78% between 2005 and 2050 in the reference scenario), while impacts for ozone depend on the ambition level of international climate policies. A move towards stringent climate policies on a global scale, in addition to limiting global warming, creates co-benefits in terms of reduced health impacts (68% decrease in life years lost from the exposure to PM2.5 and 85% decrease in premature deaths from ozone in 2050 in the mitigation scenario relative to the reference scenario) and air pollution cost savings (77%) in Europe. These co-benefits are found to offset at least 85% of the addi

Published
2015

33. The European CO2, CO, CH4 and N2O balance between 2001 and 2005

Author

Luyssaert, S, Abril, G, Andres, R, Bastviken, D, Bellassen, V, Bergamaschi, P, Bousquet, P, Chevallier, F, Ciais, P, Corazza, M, Dechow, R, Erb, Karl H, Etiope, G, Fortems-Cheiney, A, Grassi, G, Hartman, J, Jung, M, Lathiere, J, Lohila, A, Moosdorf, N, Njakou Djomo, S, Otto, J, Papale, D, Peters, W, Peylin, P, Raymond, P, Rxf6denbeck, C, Saarnio, S, Schulze, E. D, Szopa, S, Thompson, R, Verkerk, P. J, Vuichard, N, Wang, R, Wattenbach, M, and Zaehle, S.

Published
2012

34. The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 2005

Author

Luyssaert, S., Abril, G., Andres, R., Bastviken, D., Bellassen, V., Bergamaschi, P., Bousquet, P., Chevallier, F., Ciais, P., Corazza, M., Dechow, R., Erb, K., Etiope, G., Fortems-Cheiney, A., Grassi, G., Hartman, J., Jung, M., Lathière, J., Lohila, A., Moosdorf, N., Njakou Djomo, S., Otto, J., Papale, D., Peters, W., Peylin, P., Raymond, P., Rödenbeck, C., Saarnio, S., Schulze, E., Szopa, S., Thompson, R., Verkerk, P., Vuichard, N., Wang, R., Wattenbach, M., and Zaehle, S.

Subjects
550 - Earth sciences
Published
2012

35. The influence of ozone precursor emissions from four world regions on tropospheric composition and radiative climate forcing

Author

Fry, M.M., Naik, V., Duncan, B.N., Hess, P., MacKenzie, I.A., Marmer, E., Schultz, M.G., Szopa, S., Wild, O., Zeng, G., West, J.J., Schwarzkopf, M.D., Fiore, A.M., Collins, W.J., Dentener, F.J., Shindell, D.T., Atherton, C., and Bergmann, D.

Subjects
ddc:550
Abstract

Ozone (O-3) precursor emissions influence regional and global climate and air quality through changes in tropospheric O-3 and oxidants, which also influence methane (CH4) and sulfate aerosols (SO42-). We examine changes in the tropospheric composition of O-3, CH4, SO42- and global net radiative forcing (RF) for 20% reductions in global CH4 burden and in anthropogenic O-3 precursor emissions (NOx, NMVOC, and CO) from four regions (East Asia, Europe and Northern Africa, North America, and South Asia) using the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model (CTM) simulations, assessing uncertainty (mean +/- 1 standard deviation) across multiple CTMs. We evaluate steady state O-3 responses, including long-term feedbacks via CH4. With a radiative transfer model that includes greenhouse gases and the aerosol direct effect, we find that regional NOx reductions produce global, annually averaged positive net RFs (0.2 +/- 0.6 to 1.7 +/- 2 mWm(-2)/TgN yr(-1)), with some variation among models. Negative net RFs result from reductions in global CH4 (-162.6 +/- 2 mWm(-2) for a change from 1760 to 1408 ppbv CH4) and regional NMVOC (-0.4 +/- 0.2 to -0.7 +/- 0.2 mWm(-2)/Tg C yr(-1)) and CO emissions (-0.13 +/- 0.02 to -0.15 +/- 0.02 mWm(-2)/Tg CO yr(-1)). Including the effect of O-3 on CO2 uptake by vegetation likely makes these net RFs more negative by -1.9 to -5.2 mWm(-2)/Tg N yr(-1), -0.2 to -0.7 mWm(-2)/Tg C yr(-1), and -0.02 to -0.05 mWm(-2)/Tg CO yr(-1). Net RF impacts reflect the distribution of concentration changes, where RF is affected locally by changes in SO42-, regionally to hemispherically by O-3, and globally by CH4. Global annual average SO42- responses to oxidant changes range from 0.4 +/- 2.6 to -1.9 +/- 1.3 Gg for NOx reductions, 0.1 +/- 1.2 to -0.9 +/- 0.8 Gg for NMVOC reductions, and -0.09 +/- 0.5 to -0.9 +/- 0.8 Gg for CO reductions, suggesting additional research is needed. The 100-year global warming potentials (GWP(100)) are calculated for the global CH4 reduction (20.9 +/- 3.7 without stratospheric O-3 or water vapor, 24.2 +/- 4.2 including those components), and for the regional NOx, NMVOC, and CO reductions (-18.7 +/- 25.9 to -1.9 +/- 8.7 for NOx, 4.8 +/- 1.7 to 8.3 +/- 1.9 for NMVOC, and 1.5 +/- 0.4 to 1.7 +/- 0.5 for CO). Variation in GWP(100) for NOx, NMVOC, and CO suggests that regionally specific GWPs may be necessary and could support the inclusion

Published
2012
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36. Ten years of CO emissions as seen from MOPITT

Author

Audrey, C., Chevallier, F., Pison, I., Bousquet, P., Szopa, S., Clerbaux, Cathy, Deeter, M. N., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and National Center for Atmospheric Research [Boulder] (NCAR)

Subjects
Troposphere: composition and chemistry, [SDU]Sciences of the Universe [physics]
Abstract

International audience; Satellites data can be combined in sophisticated inversion systems that take the impact of the chemistry of the lower atmosphere into account. In order to improve our knowledge of the emissions of greenhouse gases and of their precursors at the global scale, we have developed a multi-species inversion system of the emission fluxes and 3D-production of the gases involved in the oxidation chain of methane (CH4 ), in particular carbon monoxide (CO) and formaldehyde (HCHO), reacting with hydroxyl radicals (OH). The inverse modelling approach offers an attractive solution to the problem of estimating the gaseous emissions, that allows to correct the prior inventories. For the first time, this study aims at estimating the CO emissions for the past ten years (from March 2000 to December 2009), using our multi-species inversion system and the MOPITT Version 4 retrievals. Our validation strategy consists in comparing our posterior-modelled concentrations with several sets of independent measurements: surface measurements, aircraft and satellite. The posterior emissions, with a global 10-year average of 1368 TgCO/yr, are 37% higher than the prior ones, built from the EDGAR 3.2 and the GFEDv2 inventories (1005 TgCO/yr on average). In addition, they present some significant and challenging seasonal variations in the northern hemisphere that are not present in our prior nor in others major inventories (IPCC AR5, RETRO, EPA, EMEP). Our results exhibit some large interannual variability due to biomass burning emissions, climate, and socioeconomic factors. Indeed, the highest annual budget of the last decade is seen for year 2007 with 1457 TgCO/yr, because of fires over South East Asia and South American Temperate. Then, the CO emissions show a dramatic decrease (1277 TgCO/yr in 2009), that could be connected to the economic recession.

Published
2010

37. Changes in tropospheric aerosol and reactive gases burdens and concentrations under IPCC-AR5 emission scenarios for 1850-2100

Author

Szopa, S., Balkanski, Y., Cozic, A., Cugnet, David, Déandreis, C., Dufresne, J., Hauglustaine, D., Foujols, M., Lathière, J., de Noblet-Ducoudré, N., Schulz, M., Yan, N., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Troposphere: composition and chemistry, [SDU]Sciences of the Universe [physics], Evolution of the atmosphere, Geochemical cycles
Abstract

International audience; Tropospheric ozone and aerosols are major climate forcing agents but the quantification of their forcings are still highly uncertain. In the framework of the ACC-MIP, a global decadal dataset describing the emissions of aerosols and ozone precursors and consistent with those provided for long-lived GHG, was made available. It allowed chemistry-climate models to simulate the evolution of short-lived GHG over the historical period (1850-2005) and for 4 future projections (Representative Concentration Pathways). This work describes the results obtained with the LMDz-INCA model using these state-of-the-art emissions and considering past and future climate change trajectories in a General Circulation Model. These concentrations are currently used as forcing by the two French Earth system models (IPSL-CM5 and CNRM-CM5) to simulate the climate evolution in the CMIP5 framework. The variability and trends of the concentrations along with their relevance will be discussed. In parallel to these projections considering the anthropogenic emissions changes, a short insight on the potential impact of natural isoprene emission changes on ozone will be shown.

Published
2010

40. Multi-species inversion of CH4, CO and H2 emissions from surface measurements

Author

Pison, I., Bousquet, P., Chevallier, F., Szopa, S., Didier Hauglustaine, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-RAMCES (ICOS-RAMCES), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Modélisation du climat (CLIM), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; In order to study the spatial and temporal variations of the emissions of greenhouse gases and of their precursors , we developed a data assimilation system and applied it to infer emissions of CH 4 , CO and H 2 for one year. It is based on an atmospheric chemical transport model and on a simplified scheme for the oxidation chain of hydrocarbons , including methane, formaldehyde, carbon monoxide and molecular hydrogen together with methyl chloroform. The methodology is exposed and a first attempt at evaluating the inverted fluxes is made. Inversions of the emission fluxes of CO, CH 4 and H 2 and concentrations of HCHO and OH were performed for the year 2004, using surface concentration measurements of CO, CH 4 , H 2 and CH 3 CCl 3 as constraints. Independent data from ship and aircraft measurements and satellite retrievals are used to evaluate the results. The total emitted mass of CO is 30% higher after the inversion , due to increased fluxes by up to 35% in the Northern Hemisphere. The spatial distribution of emissions of CH 4 is modified by a decrease of fluxes in boreal areas up to 60%. The comparison between mono-and multi-species inversions shows that the results are close at a global scale but may significantly differ at a regional scale because of the interactions between the various tracers during the inversion.

Published
2009
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41. Global ozone and air quality: a multi-model assessment of risks to human health and crops

Author

Ellingsen, K., Gauss, M., Dingenen, R., Dentener, F. J., Emberson, L., Fiore, Arlene M., Schultz, M. G., Stevenson, D. S., Ashmore, M. R., Atherton, C. S., Bergmann, D. J., Bey, I., Butler, T., Drevet, J., Eskes, H., Hauglustaine, D. A., Isaksen, I. S. A., Horowitz, L. W., Krol, M., Lamarque, J. F., Lawrence, M. G., Noije, T., Pyle, J., Rast, S., Rodriguez, J., Savage, N., Strahan, S., Sudo, K., Szopa, S., Oliver Wild, University of Oslo (UiO), Joint Research Centre, Stockholm Environment Institute, NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, University of Edinburgh, Lawrence Livermore National Laboratory (LLNL), Ecole Polytechnique Fédérale de Lausanne (EPFL), Max Planck Institute for Chemistry (MPIC), Royal Netherlands Meteorological Institute (KNMI), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), National Center for Atmospheric Research [Boulder] (NCAR), University of Cambridge [UK] (CAM), Goddard Earth Sciences and Technology Center (GEST), University of Maryland [Baltimore County] (UMBC), University of Maryland System-University of Maryland System, Frontier Research Center for Global Change (FRCGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract

International audience; Within ACCENT, a European Network of Excellence, eighteen atmospheric models from the U.S., Europe, and Japan calculated present (2000) and future (2030) concentrations of ozone at the Earth's surface with hourly temporal resolution. Comparison of model results with surface ozone measurements in 14 world regions indicates that levels and seasonality of surface ozone in North America and Europe are characterized well by global models, with annual average biases typically within 5–10 nmol/mol. However, comparison with rather sparse observations over some regions suggest that most models overestimate annual ozone by 15–20 nmol/mol in some locations. Two scenarios from the International Institute for Applied Systems Analysis (IIASA) and one from the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) have been implemented in the models. This study focuses on changes in near-surface ozone and their effects on human health and vegetation. Different indices and air quality standards are used to characterise air quality. We show that often the calculated changes in the different indices are closely inter-related. Indices using lower thresholds are more consistent between the models, and are recommended for global model analysis. Our analysis indicates that currently about two-thirds of the regions considered do not meet health air quality standards, whereas only 2–4 regions remain below the threshold. Calculated air quality exceedances show moderate deterioration by 2030 if current emissions legislation is followed and slight improvements if current emissions reduction technology is used optimally. For the "business as usual" scenario severe air quality problems are predicted. We show that model simulations of air quality indices are particularly sensitive to how well ozone is represented, and improved accuracy is needed for future projections. Additional measurements are needed to allow a more quantitative assessment of the risks to human health and vegetation from changing levels of surface ozone.

Published
2008

42. A multi-model source-receptor study of the hemispheric transport and deposition of oxidised nitrogen

Author

Sanderson, M.G., Dentener, F.J., Duncan, B. N., Hess, P., Horowitz, L.W., Jacob, D., Jonson, J.-E., Kaminski, J.W., Lupu, A., Mackenzie, I.A., Mancini, E., Marmer, E., Fiore, A.M., Park, R., Pitari, G., Prather, M.J., Pringle, K.J., Schroeder, S., Schultz, M. G., Shindell, D.T., Szopa, S., Wild, O., Wind, P., Cuvelier, C., Keating, T.J., Zuber, A., Atherton, C.S., Bergmann, D.J., Diehl, T., and Doherty, R.M.

Subjects
ddc:550
Abstract

Fifteen chemistry-transport models are used to quantify, for the first time, the export of oxidised nitrogen (NOy) to and from four regions (Europe, North America, South Asia, and East Asia), and to estimate the uncertainty in the results. Between 12 and 24% of the NOx emitted is exported from each region annually. The strongest impact of each source region on a foreign region is: Europe on East Asia, North America on Europe, South Asia on East Asia, and East Asia on North America. Europe exports the most NOy, and East Asia the least. East Asia receives the most NOy from the other regions. Between 8 and 15% of NOx emitted in each region is transported over distances larger than 1000 km, with 3-10% ultimately deposited over the foreign regions.

Published
2008
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43. REanalysis of the TROpospheric chemical composition over the past 40 years FIRE ENGINE View project FUELMON -remote FUEL break MONitoring for forest fire protection View project

Author

Schultz, M.G., Backman, L., Balkanski, Yves, Bjoerndalsaeter, S., Brand, R., Burrows, J.P., Dalsoeren, S., de Vasconcelos, M., Grodtmann, B., Hauglustaine, D. A., Heil, A., Hoelzemann, J. J., Isaksen, I.S.A., Kaurola, J., Knorr, W., Ladstaetter-Weißenmayer, A., Mota, B., Oom, D., Pacyna, J., Panasiuk, D., Pereira, J. M. C., Pulles, T., Pyle, J., Rast, S., Richter, A., Savage, N., Schnadt, C., M., Schulz, Spessa, A, Staehelin, J., Sundet, J.K., Szopa, S., Thonicke, K., van het Bolscher, M., Van Noije, T., Van Velthoven, P., Vik, A. F., Wittrock, F., Max-Planck-Institut für Meteorologie (MPI-M), Max-Planck-Gesellschaft, and Max-Planck-Institut für Meteorologie e.V., Hamburg

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

REanalysis of the TROpospheric chemical composition over thepast 40 years (RETRO)Objectives:• exploit (often under-utilised) existing data sets from ground based stations,aircraft, and satellite instruments, integrating these into common datasets,• develop tools for the analysis, interpretation and exploitation of the data,• formulate recommendations for future measurement strategies,• assess changes in trace compound emissions and their effect on troposphericchemical composition and aerosols, and the associated radiative forcing, overthe past 40 years,• provide an assessment of uncertainties caused by climate variability,• evaluate emission control strategies in Europe,• predict changes over the next 20 years in tropospheric composition, andradiative forcing through model studies using the emission scenarios definedfor the IPCC 2001 climate assessment,• analyze the magnitude of intercontinental pollutant transport.Scientific achievements:• first detailed, comprehensive and consistent data sets on global emissionsfrom fossil and biofuel combustion and from open vegetation burningcovering the time period 1960-2000; available as gridded data sets with0.5°×0.5° and monthly mean resolution,• first global long-term atmospheric chemistry integrations with several stateof-the-art models using the ERA-40 meteorological data, the RETROemissions and other constrains in a consistent and well-documented manner,• analysis of key parameters controlling the interannual and seasonalvariability and the longer-term trends in the tropospheric composition relatedto ozone and its precursors,• development of new software tools for the analysis of observational data andmodel results; standardisation of model output and data formats anddefinition of model evaluation metrics and skill scores,• development of a comprehensive data base for tropospheric compositionobservations with complete metadata definition and a user-friendly interfacefor data access,• multi-model analysis of specific scenarios related to power generation andthe traffic sector in OECD countries,• contributions to the IPCC 4th assessment report through participation in amulti-model assessment study coordinated by the ACCENT network ofexcellenceMain deliverables:• gridded data sets of global emissions from 1960 to 2000 (D1-4)• gridded data sets of simulated concentrations of ozone and ozone precursorsfrom 1960 to 2000 (D4-3)• data base of atmospheric observationsreport on the RETRO emission inventories (D1-6)o report on trend analysis based on observational data (D2-3)o reports on sensitivity studies (D3-2, D3-3 and D3-4)o report on the long-term reanalysis simulations (D4-4)o reports on changes in UV and radiative forcing (D5-1 and D5-2)o analysis of past policy measures including scenario studies (D5-5)All RETRO deliverables are available on the RETRO ftp serverftp://ftp.retro.enes.org/pub or via the RETRO web pages http://retro.enes.org.Socio-economic relevance and policy implications:Understanding past trends in large-scale air pollution is a key requirement toformulate future strategies to enhance air quality in Europe and elsewhere. Due tothe scarcity of observational data (particularly for years before 1990), numericalmodels are the only way to obtain comprehensive and consistent information onpast trends in tropospheric ozone and related substances. The model simulationsin RETRO also allow for evaluating the impact of important parameters on theinterannual variability of air pollution in Europe. From specific sensitivity studiesthe roles of meteorological variability, variability in anthropogenic emissions andvariability in wildland fire emissions could be determined. Scenario calculationson the impact of certain policy measures to reduce emissions from powergeneration or from the traffic sector provide a direct answer to the potentialconsequences of the introduction of more stringent air pollution abatementmeasures. Due to the effects of intercontinental transport of air pollution, localmeasures may not always achieve the expected results. These issues can only beaddressed with comprehensive, well-constrained global model simulations as theywere pioneered in the RETRO project. Several of the tools and methodologiesdeveloped in RETRO are now applied in ongoing projects with a more immediatepolicy link (especially the FP6 integrated project GEMS and the multi-modelassessment activity under the auspices of the task force on hemispheric transportof air pollution).Conclusions:• RETRO contributed significant developments to advance the state-of-the-artin global atmospheric chemistry modelling in terms of new long-termemissions data and the first comprehensive long-term multi-modelintegrations of atmospheric chemistry and transport,• The RETRO models generally show very good consistency in terms ofinterannual variability and trend patterns, but they occasionally differsignificantly in the absolute values of the simulated concentrations of ozoneand its precursors,• Comparison with observations shows that the RETRO models often capturethe atmospheric variability patterns rather well and that the mean modelgenerally provides a reasonable description of the chemical state of theatmosphere. Some exceptions are noted, in particular the absence of anincreasing ozone trend over central Europe in the 1990s which is clearly seenfrom measurements at several mountain stations,• According to the RETRO simulations, summertime boundary layerconcentrations of ozone over Europe increased between 5 and 15 ppb (10-20%) between 1960 and the year 2000. Further abatement measures in thetraffic sector (introduction of the EURO 5 standard in all OECD countries)could lead to a reduction of summertime ozone by 8-10%.• A renewed effort following on the RETRO activities would be highlydesirable in order to further expand the available emission data sets(inclusion of SO2, aerosol precursors and greenhouse gases and review ofnatural emissions), to further investigate the underlying causes fortropospheric composition change and to include the analysis of feedbacksbetween tropospheric ozone, climate change and aerosols.Dissemination of results:• more than 30 articles appeared in peer reviewed scientific journals with director indirect contributions from the RETRO project,• RETRO project results were presented in more than 100 conferencecontributions and presentations at international meetings,• a specific session on “tropospheric trends and variability” was inaugurated atthe EGU General Symposium 2004 and was repeated in 2006 and 2007,• RETRO emission data sets are being used in several ongoing researchprojects (e.g. GEMS and TFHTAP, GREENCYCLES, etc.),• All RETRO data sets and reports are available on the RETRO ftp serverftp://ftp.retro.enes.org/pub or via the RETRO web pages athttp://retro.enes.org.

Published
2007

44. Multi-model ensemble simulations of tropospheric NO2 compared with GOME retrievals for the year 2000

Author

van Noije, T., Eskes, H., Dentener, F., Stevenson, D., Ellingsen, K., Schultz, M., Wild, O., Amann, M., Butler, T., Cofala, J., Drevet, J., Fiore, A., Gauss, M., Hauglustaine, D., Horowitz, L., Isaksen, I., Krol, M., Lamarque, J., Lawrence, M., Martin, R., Montanaro, V., Mueller, J., Pitari, G., Prather, M., Pyle, J., Richter, A., Rodriguez, J., Savage, N., Strahan, S., Sudo, K., Szopa, S., and van Roozendaal, M.

Abstract

We present a systematic comparison of tropospheric NO2 from 17 global atmospheric chemistry models with three state-of-the-art retrievals from the Global Ozone Monitoring Experiment (GOME) for the year 2000. The models used constant anthropogenic emissions from IIASA/EDGAR3.2 and monthly emissions from biomass burning based on the 1997–2002 average carbon emissions from the Global Fire Emissions Database (GFED). Model output is analyzed at 10:30 local time, close to the overpass time of the ERS-2 satellite, and collocated with the measurements to account for sampling biases due to incomplete spatiotemporal coverage of the instrument. We assessed the importance of different contributions to the sampling bias: correlations on seasonal time scale give rise to a positive bias of 30–50% in the retrieved annual means over regions dominated by emissions from biomass burning. Over the industrial regions of the eastern United States, Europe and eastern China the retrieved annual means have a negative bias with significant contributions (between –25% and +10% of the NO2 column) resulting from correlations on time scales from a day to a month. We present global maps of modeled and retrieved annual mean NO2 column densities, together with the corresponding ensemble means and standard deviations for models and retrievals. The spatial correlation between the individual models and retrievals are high, typically in the range 0.81–0.93 after smoothing the data to a common resolution. On average the models underestimate the retrievals in industrial regions, especially over eastern China and over the Highveld region of South Africa, and overestimate the retrievals in regions dominated by biomass burning during the dry season. The discrepancy over South America south of the Amazon disappears when we use the GFED emissions specific to the year 2000. The seasonal cycle is analyzed in detail for eight different continental regions. Over regions dominated by biomass burning, the timing of the seasonal cycle is generally well reproduced by the models. However, over Central Africa south of the Equator the models peak one to two months earlier than the retrievals. We further evaluate a recent proposal to reduce the NOx emission factors for savanna fires by 40% and find that this leads to an improvement of the amplitude of the seasonal cycle over the biomass burning regions of Northern and Central Africa. In these regions the models tend to underestimate the retrievals during the wet season, suggesting that the soil emissions are higher than assumed in the models. In general, the discrepancies between models and retrievals cannot be explained by a priori profile assumptions made in the retrievals, neither by diurnal variations in anthropogenic emissions, which lead to a marginal reduction of the NO2 abundance at 10:30 local time (by 2.5–4.1% over Europe). Overall, there are significant differences among the various models and, in particular, among the three retrievals. The discrepancies among the retrievals (10–50% in the annual mean over polluted regions) indicate that the previously estimated retrieval uncertainties have a large systematic component. Our findings imply that top-down estimations of NOx emissions from satellite retrievals of tropospheric NO2 are strongly dependent on the choice of model and retrieval.

Published
2006

45. Multi-model ensemble simulations of troposphere NO2 compared with GOME retrievals for the year 2000

Author

van Noije, T. P. C., Eskes, H.J., Bey, I., Boersma, K. F., Butler, T., Cofala, J., Drevet, J., Fiore, A. M., Gauss, M., Hauglustaine, D. A., Horowitz, L. W., Isaksen, I. S. A., Dentener, F. J., Krol, M. C., Lamarque, J.-F., Lawrence, M. G., Martin, R. V., Montanaro, V., Müller, J.-F., Pitari, G., Prather, M. J., Pyle, J. A., Richter, A., Stevenson, D. S., Rodriguez, J. M., Savage, N. H., Strahan, S.E., Sudo, K., Szopa, S., van Roozendael, M., Ellingsen, K., Schultz, M. G., Wild, O., Amann, M., Atherton, C. S., and Bergmann, D. J.

Subjects
ddc:550
Abstract

We present a systematic comparison of tropospheric NO2 from 17 global atmospheric chemistry models with three state-of-the-art retrievals from the Global Ozone Monitoring Experiment (GOME) for the year 2000. The models used constant anthropogenic emissions from IIASA/EDGAR3.2 and monthly emissions from biomass burning based on the 1997 - 2002 average carbon emissions from the Global Fire Emissions Database (GFED). Model output is analyzed at 10: 30 local time, close to the overpass time of the ERS-2 satellite, and collocated with the measurements to account for sampling biases due to incomplete spatiotemporal coverage of the instrument. We assessed the importance of different contributions to the sampling bias: correlations on seasonal time scale give rise to a positive bias of 30 - 50% in the retrieved annual means over regions dominated by emissions from biomass burning. Over the industrial regions of the eastern United States, Europe and eastern China the retrieved annual means have a negative bias with significant contributions ( between - 25% and + 10% of the NO2 column) resulting from correlations on time scales from a day to a month. We present global maps of modeled and retrieved annual mean NO2 column densities, together with the corresponding ensemble means and standard deviations for models and retrievals. The spatial correlation between the individual models and retrievals are high, typically in the range 0.81 - 0.93 after smoothing the data to a common resolution. On average the models underestimate the retrievals in industrial regions, especially over eastern China and over the Highveld region of South Africa, and overestimate the retrievals in regions dominated by biomass burning during the dry season. The discrepancy over South America south of the Amazon disappears when we use the GFED emissions specific to the year 2000. The seasonal cycle is analyzed in detail for eight different continental regions. Over regions dominated by biomass burning, the timing of the seasonal cycle is generally well reproduced by the models. However, over Central Africa south of the Equator the models peak one to two months earlier than the retrievals. We further evaluate a recent proposal to reduce the NOx emission factors for savanna fires by 40% and find that this leads to an improvement of the amplitude of the seasonal cycle over the biomass burning regions of Northern and Central Africa. In these regions the models tend to underestimate the retrievals during the wet season, suggesting that the soil emissions are higher than assumed in the models. In general, the discrepancies between models and retrievals cannot be explained by a priori profile assumptions made in the retrievals, neither by diurnal variations in anthropogenic emissions, which lead to a marginal reduction of the NO2 abundance at 10: 30 local time ( by 2.5 - 4.1% over Europe). Overall, there are significant differences among the various models and, in particular, among the three retrievals. The discrepancies among the retrievals ( 10 - 50% in the annual mean over polluted regions) indicate that the previously estimated retrieval uncertainties have a large systematic component. Our findings imply that top-down estimations of NOx emissions from satellite retrievals of tropospheric NO2 are strongly dependent on the choice of model and retrieval.

Published
2006
Full Text
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46. MULTI-MODEL ENSEMBLE SIMULATIONS OF TROPOSPHERIC NO2 COMPARED WITH GOME RETRIEVALS FOR THE YEAR 2000

Author

Van, Noije, T. P. C., Eskes, H. J., Dentener, F. J., Stevenson, D. S., Ellingsen, K., Schultz, M. G., Wild, O., Amann, M., Atherton, C. S., Bergmann, D. J., Bey, I., Boersma, K. F., Butler, T., Cofala, J., Drevet, J., Fiore, A. M., Gauss, M., Hauglustaine, D. A., Horowitz, L. W., Isaksen, I. S. A., Krol, M. C., Lamarque, J. F., Lawrence, M. G., Martin, R. V., Montanaro, V., Müller, J. F., Pitari, Giovanni, Prather, M. J., Pyle, J. A., Richter, A., Rodriguez, J. M., Savage, N. H., Strahan, S. E., Sudo, K., Szopa, S., and VAN ROOZENDAEL, AND M.

Published
2006

47. Nitrogen and sulfar desposition on regional and global scales: A multimodel evaluation

Author

Dentener, F., Drevet, J., Lamarque, J.F., Bey, I., Eickhout, B., Fiore, A.M., Hauglustaine, D., Horowitz, L.W., Krol, M.C., Kulshrestha, U.C., Lawrence, M., Galy-Lacaux, C., Rast, S., Shindell, D., Stevenson, D., van Noije, T., Atherton, C., Bell, N., Bergman, D., Butler, T., Cofala, J., Collins, B., Doherty, R., Ellingsen, K., Galloway, J., Gauss, M., Montanaro, V., Müller, J.F., Pitari, G., Rodriguez, J., Sanderson, M., Solmon, F., Strahan, S., Schultz, M., Sudo, K., Szopa, S., and Wild, O.

Subjects
Meteorologie en Luchtkwaliteit, future, tropospheric ozone, WIMEK, model, Meteorology and Air Quality, cycle, emissions, ammonia, aerocom, ecosystems, europe, biodiversity hotspots
Abstract

We use 23 atmospheric chemistry transport models to calculate current and future (2030) deposition of reactive nitrogen (NOy, NHx) and sulfate (SOx) to land and ocean surfaces. The models are driven by three emission scenarios: (1) current air quality legislation (CLE); (2) an optimistic case of the maximum emissions reductions currently technologically feasible (MFR); and (3) the contrasting pessimistic IPCC SRES A2 scenario. An extensive evaluation of the present-day deposition using nearly all information on wet deposition available worldwide shows a good agreement with observations in Europe and North America, where 60–70% of the model-calculated wet deposition rates agree to within ±50% with quality-controlled measurements. Models systematically overestimate NHx deposition in South Asia, and underestimate NOy deposition in East Asia. We show that there are substantial differences among models for the removal mechanisms of NOy, NHx, and SOx, leading to ±1 s variance in total deposition fluxes of about 30% in the anthropogenic emissions regions, and up to a factor of 2 outside. In all cases the mean model constructed from the ensemble calculations is among the best when comparing to measurements. Currently, 36–51% of all NOy, NHx, and SOx is deposited over the ocean, and 50–80% of the fraction of deposition on land falls on natural (nonagricultural) vegetation. Currently, 11% of the world's natural vegetation receives nitrogen deposition in excess of the “critical load” threshold of 1000 mg(N) m-2 yr-1. The regions most affected are the United States (20% of vegetation), western Europe (30%), eastern Europe (80%), South Asia (60%), East Asia (40%), southeast Asia (30%), and Japan (50%). Future deposition fluxes are mainly driven by changes in emissions, and less importantly by changes in atmospheric chemistry and climate. The global fraction of vegetation exposed to nitrogen loads in excess of 1000 mg(N) m-2 yr-1 increases globally to 17% for CLE and 25% for A2. In MFR, the reductions in NOy are offset by further increases for NHx deposition. The regions most affected by exceedingly high nitrogen loads for CLE and A2 are Europe and Asia, but also parts of Africa.

Published
2006

48. Assessment of the reduction methods used to develop chemical schemes: building of a new chemical scheme for VOC oxidation suited to three-dimensional multiscale HOx-NOx-VOC chemistry simulations

Author

Szopa, S., Bernard Aumont, Madronich, S., Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation du climat (CLIM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), National Center for Atmospheric Research [Boulder] (NCAR), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and EGU, Publication

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract

International audience; The objective of this work was to develop and assess an automatic procedure to generate reduced chemical schemes for the atmospheric photooxidation of volatile organic carbon (VOC) compounds. The procedure is based on (i) the development of a tool for writing the fully explicit schemes for VOC oxidation (see companion paper Aumont et al., 2005), (ii) the application of several commonly used reduction methods to the fully explicit scheme, and (iii) the assessment of resulting errors based on direct comparison between the reduced and full schemes. The reference scheme included seventy emitted VOCs chosen to be representative of both anthropogenic and biogenic emissions, and their atmospheric degradation chemistry required more than two million reactions among 350000 species. Three methods were applied to reduce the size of the reference chemical scheme: (i) use of operators, based on the redundancy of the reaction sequences involved in the VOC oxidation, (ii) grouping of primary species having similar reactivities into surrogate species and (iii) grouping of some secondary products into surrogate species. The number of species in the final reduced scheme is 147, this being small enough for practical inclusion in current three-dimensional models. Comparisons between the fully explicit and reduced schemes, carried out with a box model for several typical tropospheric conditions, showed that the reduced chemical scheme accurately predicts ozone concentrations and some other aspects of oxidant chemistry for both polluted and clean tropospheric conditions.

Published
2005
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49. Impact of the Asian monsoon anticyclone on the variability of mid-to-upper tropospheric methane above the Mediterranean Basin

Author

Ricaud, P., primary, Sič, B., additional, El Amraoui, L., additional, Attié, J.-L., additional, Zbinden, R., additional, Huszar, P., additional, Szopa, S., additional, Parmentier, J., additional, Jaidan, N., additional, Michou, M., additional, Abida, R., additional, Carminati, F., additional, Hauglustaine, D., additional, August, T., additional, Warner, J., additional, Imasu, R., additional, Saitoh, N., additional, and Peuch, V.-H., additional

Published
2014
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50. Variability of tropospheric methane above the Mediterranean Basin inferred from satellite and model data

Author

Ricaud, P., primary, Sič, B., additional, El Amraoui, L., additional, Attié, J.-L., additional, Huszar, P., additional, Szopa, S., additional, Parmentier, J., additional, Jaidan, N., additional, Michou, M., additional, Abida, R., additional, Zbinden, R., additional, Carminati, F., additional, Hauglustaine, D., additional, August, T., additional, Warner, J., additional, Imasu, R., additional, Saitoh, N., additional, and Peuch, V.-H., additional

Published
2014
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