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315 results on '"Beerling, D. J."'

1. Cold‐Season Methane Fluxes Simulated by GCP‐CH4 Models

Author

Ito, A., primary, Li, T., additional, Qin, Z., additional, Melton, J. R., additional, Tian, H., additional, Kleinen, T., additional, Zhang, W., additional, Zhang, Z., additional, Joos, F., additional, Ciais, P., additional, Hopcroft, P. O., additional, Beerling, D. J., additional, Liu, X., additional, Zhuang, Q., additional, Zhu, Q., additional, Peng, C., additional, Chang, K.‐Y., additional, Fluet‐Chouinard, E., additional, McNicol, G., additional, Patra, P., additional, Poulter, B., additional, Sitch, S., additional, and Riley, W., additional

Published
2023
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26. Cold‐Season Methane Fluxes Simulated by GCP‐CH4 Models.

Author

Ito, A., Li, T., Qin, Z., Melton, J. R., Tian, H., Kleinen, T., Zhang, W., Zhang, Z., Joos, F., Ciais, P., Hopcroft, P. O., Beerling, D. J., Liu, X., Zhuang, Q., Zhu, Q., Peng, C., Chang, K.‐Y., Fluet‐Chouinard, E., McNicol, G., and Patra, P.

Subjects
WETLANDS, ATMOSPHERIC methane, METHANE, FIELD research, ATMOSPHERIC temperature
Abstract

Cold‐season methane (CH4) emissions may be poorly constrained in wetland models. We examined cold‐season CH4 emissions simulated by 16 models participating in the Global Carbon Project model intercomparison and analyzed temporal and spatial patterns in simulation results using prescribed inundation data for 2000–2020. Estimated annual CH4 emissions from northern (>60°N) wetlands averaged 10.0 ± 5.5 Tg CH4 yr−1. While summer CH4 emissions were well simulated compared to in‐situ flux measurement observations, the models underestimated CH4 during September to May relative to annual total (27 ± 9%, compared to 45% in observations) and substantially in the months with subzero air temperatures (5 ± 5%, compared to 27% in observations). Because of winter warming, nevertheless, the contribution of cold‐season emissions was simulated to increase at 0.4 ± 0.8% decade−1. Different parameterizations of processes, for example, freezing–thawing and snow insulation, caused conspicuous variability among models, implying the necessity of model refinement. Plain Language Summary: Wetlands in the northern high latitudes are a major source of methane (CH4) to the atmosphere, mainly during the warm season. Previously, models have assumed that cold‐season CH4 emissions are low, but recent observations suggest high‐latitude wetlands can be substantial sources even in winter. We compared CH4 emissions simulated by 16 state‐of‐the‐art wetland models, participating in a model intercomparison project with a focus on the cold‐season in northern wetlands. The model simulations indicated that nearly one third of annual emissions were simulated to occur from September to May, and CH4 emissions to the atmosphere were not negligible even under freezing air temperatures, although the results differed greatly among the models. However, field studies suggest cold‐season emissions account for an even larger fraction of annual emissions. These results highlight the contribution of cold‐season emissions to the annual CH4 budget, which future climatic warming is expected to affect severely, and they also show that simulations of cold‐season CH4 emissions from wetlands need to be improved. Key Points: Cold‐season methane (CH4) emissions simulated by 16 Global Carbon Project‐CH4 wetland models were analyzedMost models underestimate the cold‐season emissions in comparison with observational dataFurther model improvement by including cold‐season processes is required to reduce the model bias and uncertainty [ABSTRACT FROM AUTHOR]

Published
2023
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43. Climate Sensitivity in the Anthropocene

Author

Previdi, M, Liepert, B. G, Peteet, Dorothy M, Hansen, J, Beerling, D. J, Broccoli, A. J, Frolking, S, Galloway, J. N, Heimann, M, LeQuere, C, Levitus, S, and Ramaswamy, V

Subjects
Meteorology And Climatology
Abstract

Climate sensitivity in its most basic form is defined as the equilibrium change in global surface temperature that occurs in response to a climate forcing, or externally imposed perturbation of the planetary energy balance. Within this general definition, several specific forms of climate sensitivity exist that differ in terms of the types of climate feedbacks they include. Based on evidence from Earth's history, we suggest here that the relevant form of climate sensitivity in the Anthropocene (e.g. from which to base future greenhouse gas (GHG) stabilization targets) is the Earth system sensitivity including fast feedbacks from changes in water vapour, natural aerosols, clouds and sea ice, slower surface albedo feedbacks from changes in continental ice sheets and vegetation, and climate-GHG feedbacks from changes in natural (land and ocean) carbon sinks. Traditionally, only fast feedbacks have been considered (with the other feedbacks either ignored or treated as forcing), which has led to estimates of the climate sensitivity for doubled CO2 concentrations of about 3 C. The 2×CO2 Earth system sensitivity is higher than this, being approx. 4-6 C if the ice sheet/vegetation albedo feedback is included in addition to the fast feedbacks, and higher still if climate-GHG feedbacks are also included. The inclusion of climate-GHG feedbacks due to changes in the natural carbon sinks has the advantage of more directly linking anthropogenic GHG emissions with the ensuing global temperature increase, thus providing a truer indication of the climate sensitivity to human perturbations. The Earth system climate sensitivity is difficult to quantify due to the lack of palaeo-analogues for the present-day anthropogenic forcing, and the fact that ice sheet and climate-GHG feedbacks have yet to become globally significant in the Anthropocene. Furthermore, current models are unable to adequately simulate the physics of ice sheet decay and certain aspects of the natural carbon and nitrogen cycles. Obtaining quantitative estimates of the Earth system sensitivity is therefore a high priority for future work.

Published
2014
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44. Making sense of palaeoclimate sensitivity

Author

Rohling, E. J., Sluijs, A., Dijkstra, H. A., Köhler, P., van de Wal, R. S. W., von der Heydt, A. S., Beerling, D. J., Berger, A., Bijl, P. K., Crucifix, M., DeConto, R., Drijfhout, S. S., Fedorov, A., Foster, G. L., Ganopolski, A., Hansen, J., Hönisch, B., Hooghiemstra, H., Huber, M., Huybers, P., Knutti, R., Lea, D. W., Lourens, L. J., Lunt, D., Masson-Demotte, V., Medina-Elizalde, M., Otto-Bliesner, B., Pagani, M., Pälike, H., Renssen, H., Royer, D. L., Siddall, M., Valdes, P., Zachos, J. C., and Zeebe, R. E.

Published
2012
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46. The Kråkenes late-glacial palaeoenvironmental project

Author

Birks, Hilary H., Battarbee, R. W., Beerling, D. J., Birks, H. J. B., Brooks, S. J., Duigan, C. A., Gulliksen, S., Haflidason, H., Hauge, F., Jones, V. J., Jonsgard, B., Kårevik, M., Larsen, E., Lemdahl, G., Løvlie, R., Mangerud, J., Peglar, S. M., Possnert, G., Smol, J. P., Solem, J. O., Solhøy, I., Solhøy, T., Sønstegaard, E., and Wright, H. E.

Published
1996
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47. Response of photosynthesis, growth and water relations of a savannah-adapted tree and grass grown across high to low CO2

Author

Quirk, Joe, Bellasio, Chandra, Johnson, David A., Beerling, D J, Quirk, Joe, Bellasio, Chandra, Johnson, David A., and Beerling, D J

Abstract

• Background and Aims By the year 2100, atmospheric CO2 concentration ([CO2]a) could reach 800 ppm, having risen from ~200 ppm since the Neogene, beginning ~24 Myr ago. Changing [CO2]a affects plant carbon–water balance, with implications for growth, drought tolerance and vegetation shifts. The evolution of C4 photosynthesis improved plant hydraulic function under low [CO2]a and preluded the establishment of savannahs, characterized by rapid transitions between open C4-dominated grassland with scattered trees and closed forest. Understanding directional vegetation trends in response to environmental change will require modelling. But models are often eparameterized with characteristics observed in plants under current climatic conditions, necessitating experimental quantification of the mechanistic underpinnings of plant acclimation to [CO2]a. • Methods We measured growth, photosynthesis and plant–water relations, within wetting–drying cycles, of a C3 tree (Vachellia karroo, an acacia) and a C4 grass (Eragrostis curvula) grown at 200, 400 or 800 ppm [CO2]a. We investigated the mechanistic linkages between trait responses to [CO2]a under moderate soil drying, and photosynthetic characteristics. • Key results For V. karroo, higher [CO2]a increased assimilation, foliar carbon:nitrogen, biomass and leaf starch, but decreased stomatal conductance and root starch. For Eragrostis, higher [CO2]a decreased C:N, did not affect assimilation, biomass or starch, and markedly decreased stomatal conductance. Together, this meant that C4 advantages in efficient water-use over the tree were maintained with rising [CO2]a. • Conclusions Acacia and Eragrostis acclimated differently to [CO2]a, with implications for their respective responses to water limitation and environmental change. Our findings question the carbon-centric focus on factors limiting assimilation with changing [CO2]a, how they are predicted and their role in determining productivity. We emphasize the continuing import

Published
2019

48. Preface

Author

Beerling, D. J., Chaloner, W. G., and Woodward, F. I.

Published
1998

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