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11 pages, 6 figures, supplementary information https://doi.org/10.1038/s41612-021-00188-5.-- Data availability; The data generated and analyzed during the current study are available from the corresponding author YRR on reasonable request, Atlantic multidecadal variability (AMV) has been linked to the observed slowdown of global warming over 1998–2012 through its impact on the tropical Pacific. Given the global importance of tropical Pacific variability, better understanding this Atlantic–Pacific teleconnection is key for improving climate predictions, but the robustness and strength of this link are uncertain. Analyzing a multi-model set of sensitivity experiments, we find that models differ by a factor of 10 in simulating the amplitude of the Equatorial Pacific cooling response to observed AMV warming. The inter-model spread is mainly driven by different amounts of moist static energy injection from the tropical Atlantic surface into the upper troposphere. We reduce this inter-model uncertainty by analytically correcting models for their mean precipitation biases and we quantify that, following an observed 0.26 °C AMV warming, the equatorial Pacific cools by 0.11 °C with an inter-model standard deviation of 0.03 °C, Y.R.-R. was founded by the European Union’s Horizon 2020 Research and Innovation Program in the framework of the Marie Skłodowska-Curie grant INADEC (Grant agreement 800154). E.M.-C. acknowledges funding from the European Commission’s Horizon 2020 projects PRIMAVERA (Grant Agreement 641727). X.L. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement H2020-MSCA-COFUND-2016-754433. A.B. and D.N. acknowledge funding from the European Commission’s Horizon 2020 project EUCP (Grant agreement 776613). F.C. and G.D. were supported by the US National Science Foundation (NSF) under the Collaborative Research EaSM2 Grant OCE-1243015 to NCAR and by the US National Oceanic and Atmospheric Administration (NOAA) Climate Program Office under the Climate Variability and Predictability Program Grant NA13OAR4310138. NCAR is a major facility sponsored by the US NSF under Cooperative Agreement 1852977. [...] R.E., N.D., L.H., and D.S. were supported by the Met Office Hadley Center 522 Climate Program funded by BEIS and Defra and by the European Commission Horizon 2020 EUCP 523 project (GA 776613). J.L.-P. was funded by the European Union’s Horizon 2020 Research and Innovation Program in the framework of the PRIMAVERA project (Grant Agreement 641727). J.R. and D.H. were funded by NERC via NCAS and the ACSIS project (NE/N018001/1), and JR was also funded by the NERC SMURPHS project (NE/N006054/1). M.M.-R. was funded by the European Union’s Horizon 2020 Research and Innovation Program in the framework of the Marie Skłodowska-Curie grant FESTIVAL (Grant agreement 797236). E.T. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 748750 (SPFireSD project), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Phytoplankton blooms in the Arctic marginal ice zone (MIZ) can be prolific dimethylsulfide (DMS) producers, thereby influencing regional aerosol formation and cloud radiative forcing. Here we describe the distribution of DMS and its precursor dimethylsulfoniopropionate (DMSP) across the Baffin Bay receding ice edge in early summer 2016. Overall, DMS and total DMSP (DMSPt) increased towards warmer waters of Atlantic origin concurrently with more advanced ice-melt and bloom stages. Relatively high DMS and DMSPt (medians of 6.3 and 70 nM, respectively) were observed in the surface layer (0–9 m depth), and very high values (reaching 74 and 524 nM, respectively) at the subsurface biomass maximum (15–30 m depth). Microscopic and pigment analyses indicated that subsurface DMS and DMSPt peaks were associated with Phaeocystis pouchetii, which bloomed in Atlantic-influenced waters and reached unprecedented biomass levels in Baffin Bay. In surface waters, DMS concentrations and DMS:DMSPt ratios were higher in the MIZ (medians of 12 nM and 0.15, respectively) than in fully ice-covered or ice-free conditions, potentially associated with enhanced phytoplanktonic DMSP release and bacterial DMSP cleavage (high dddP:dmdA gene ratios). Mean sea–air DMS fluxes (µmol m–2 d–1) increased from 0.3 in ice-covered waters to 10 in open waters (maximum of 26) owing to concurrent trends in near-surface DMS concentrations and physical drivers of gas exchange. Using remotely sensed sea-ice coverage and a compilation of sea–air DMS flux data, we estimated that the pan-Arctic DMS emission from the MIZ (EDMS, MIZ) was 5–13 Gg S yr–1. North of 80°N, EDMS, MIZ might have increased by around 10 ± 4% yr–1 between 2003 and 2014, likely exceeding open-water emissions in June and July. We conclude that EDMS, MIZ must be taken into account to evaluate plankton-climate feedbacks in the Arctic. We acknowledge funding from AGAUR (Generalitat de Catalunya) Beatriu de Pinós postdoctoral fellowship program (MG), the Canada Excellence Research Chair in Remote Sensing of Canada’s New Arctic Frontier (MB), the Canada Research Chair on Ocean Biogeochemistry and Climate and an NSERC Discovery Grant Program and Northern Research Supplement Program (MLe), NETCARE (NSERC Climate Change and Atmospheric Research program, MLe), the U.S. National Science Foundation (NSF-OCE 1756907, DJK), Marie Curie Actions-International Outgoing Fellowship (PIOF-GA-2013-629378, JD), and ArcticNet (The Network of Centres of Excellence of Canada). This is a contribution to the research program of Québec-Océan and the Takuvik Joint International Laboratory (CNRS-France & Université Laval-Canada).

Under the influence of global warming, heatwaves are becoming a major threat in many parts of the world, affecting human health and mortality, food security, forest fires, biodiversity, energy consumption, as well as the production and transportation networks. Seasonal forecasting is a promising tool to help mitigate these impacts on society. Previous studies have highlighted some predictive capacity of seasonal forecast systems for specific strong heatwaves such as those of 2003 and 2010. To our knowledge, this study is thus the first of its kind to systematically assess the prediction skill of heatwaves over Europe in a state-of-the-art seasonal forecast system. One major prerequisite to do so is to appropriately define heatwaves. Existing heatwave indices, built to measure heatwave duration and severity, are often designed for specific impacts and thus have limited robustness for an analysis of heatwave variability. In this study, we investigate the seasonal prediction skill of European summer heatwaves in the ECMWF System 5 operational forecast system by means of several dedicated metrics, as well as its added-value compared to a simple statistical model based on the linear trend. We are able to show, for the first time, that seasonal forecasts initialized in early May can provide potentially useful information of summer heatwave propensity, which is the tendency of a season to be predisposed to the occurrence of heatwaves. This work is a contribution to the HyMeX program through the project ERA4CS-MEDSCOPE, co-funded by the Horizon 2020 Framework Program of the European Union (Grant agreement 690462). Chloe Prodhomme and Javier García-Serrano were supported by the Spanish Juan de la Cierva (IJCI-2016-30802) and Ramon y Cajal (RYC-2016-21181) programs, respectively. Rachel H. White received funding from the European Unions Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement 797961.

This paper documents the global climate model EC-Earth3-AerChem, one of the members of the EC-Earth3 family of models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6). EC-Earth3-AerChem has interactive aerosols and atmospheric chemistry and contributes to the Aerosols and Chemistry Model Intercomparison Project (AerChemMIP). In this paper, we give an overview of the model, describe in detail how it differs from the other EC-Earth3 configurations, and outline the new features compared with the previously documented version of the model (EC-Earth 2.4). We explain how the model was tuned and spun up under preindustrial conditions and characterize the model's general performance on the basis of a selection of coupled simulations conducted for CMIP6. The net energy imbalance at the top of the atmosphere in the preindustrial control simulation is on average −0.09 W m−2 with a standard deviation due to interannual variability of 0.25 W m−2, showing no significant drift. The global surface air temperature in the simulation is on average 14.08 ∘C with an interannual standard deviation of 0.17 ∘C, exhibiting a small drift of 0.015 ± 0.005 ∘C per century. The model's effective equilibrium climate sensitivity is estimated at 3.9 ∘C, and its transient climate response is estimated at 2.1 ∘C. The CMIP6 historical simulation displays spurious interdecadal variability in Northern Hemisphere temperatures, resulting in a large spread across ensemble members and a tendency to underestimate observed annual surface temperature anomalies from the early 20th century onwards. The observed warming of the Southern Hemisphere is well reproduced by the model. Compared with the ECMWF (European Centre for Medium-Range Weather Forecasts) Reanalysis version 5 (ERA5), the surface air temperature climatology for 1995–2014 has an average bias of −0.86 ± 0.05 ∘C with a standard deviation across ensemble members of 0.35 ∘C in the Northern Hemisphere and 1.29 ± 0.02 ∘C with a corresponding standard deviation of 0.05 ∘C in the Southern Hemisphere. The Southern Hemisphere warm bias is largely caused by errors in shortwave cloud radiative effects over the Southern Ocean, a deficiency of many climate models. Changes in the emissions of near-term climate forcers (NTCFs) have significant effects on the global climate from the second half of the 20th century onwards. For the SSP3-7.0 Shared Socioeconomic Pathway, the model gives a global warming at the end of the 21st century (2091–2100) of 4.9 ∘C above the preindustrial mean. A 0.5 ∘C stronger warming is obtained for the AerChemMIP scenario with reduced emissions of NTCFs. With concurrent reductions of future methane concentrations, the warming is projected to be reduced by 0.5 ∘C. The development of EC-Earth3 and ECEarth3-AerChem has benefitted from services provided by the ISENES3 project, which received funding from the European Union’s Horizon 2020 Research and Innovation program (grant agreement no. 824084). Jukka-Pekka Keskinen and Risto Makkonen wish to acknowledge the IT Center for Science, Finland (CSC) for software support and computational resources. María Gonçalves-Ageitos and Carlos Pérez García-Pando acknowledge the Partnership for Advanced Computing in Europe (PRACE) and the Spanish Supercomputing Network (RES) for awarding access to MareNostrum at the Barcelona Supercomputing Center (BSC). Financial support. Twan van Noije, Tommi Bergman, Philippe Le Sager, and Jost von Hardenberg acknowledge funding from the European Union’s Horizon 2020 Research and Innovation program (CRESCENDO, grant agreement no. 641816). María GonçalvesAgeitos and Carlos Pérez García-Pando acknowledge funding from the European Research Council (FRAGMENT, grant agreement no. 773051); the AXA Research Fund; and the Spanish Ministry of Science, Innovation and Universities (grant agreement nos. RYC-2015- 18690 and CGL2017-88911-R). Roland Schrödner acknowledges funding from the strategic research area MERGE (Modelling the Regional and Global Earth system). Peer Reviewed Objectius de Desenvolupament Sostenible::13 - Acció per al Clima::13.3 - Millorar l’educació, la conscienciació i la capacitat humana i institucional en relació amb la mitigació del canvi climàtic, l’adaptació a aquest, la reducció dels efectes i l’alerta primerenca Objectius de Desenvolupament Sostenible::13 - Acció per al Clima

Microwave radiometry at L-band is sensitive to sea ice thickness (SIT) up to ∼ 60 cm. Current methods to infer SIT depend on ice-physical properties and data provided by the ESA’s Soil Moisture and Ocean Salinity (SMOS) mission. However, retrieval accuracy is limited due to seasonally and regionally variable surface conditions during the formation and melting of sea ice. In this work, Arctic sea ice is segmented using a Bayesian unsupervised learning algorithm aiming to recognize spatial patterns by harnessing multi-incidence angle brightness temperature observations. The approach considers both statistical characteristics and spatial correlations of the observations. The temporal stability and separability of classes are analyzed to distinguish ambiguous from well-determined regions. Model uncertainty is quantified from class membership probabilities using information entropy. The presented approach opens up a new scope to improve current SIT retrieval algorithms, and can be particularly beneficial to investigate merged satellite products., There are no perceived conicts of inter-est for the lead author or coauthors. The lead author received the support of a fellowship from “la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/DI18/11660050. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 713673. It was also funded through the award “Unidad de Excelencia María de Maeztu” MDM-2016-0600, by the Spanish Ministry of Science and Innovation through the project “L-band” ESP2017-89463-C3-2-R, and the project “Sensing with Pioneering Opportunistic Techniques (SPOT)” RTI2018-099008-B-C21/AEI/10.13039/501100011033

Special issue Selected Papers from the 2019 IMEKO TC-19 International Workshop on Metrology for the Sea.-- 17 pages, 11 figures, 1 table, 1 appendix, supplementary material https://doi.org/10.3390/s20092658, Since 2014, the global land and sea surface temperature has scaled 0.23 °C above the decadal average (2009–2018). Reports indicate that Mediterranean Sea temperatures have been rising at faster rates than in the global ocean. Oceanographic time series of physical and biogeochemical data collected from an onboard and a multisensor mooring array in the northwestern Mediterranean Sea (Blanes submarine canyon, Balearic Sea) during 2009–2018 revealed an abrupt temperature rising since 2014, in line with regional and global warming. Since 2014, the oligotrophic conditions of the water column have intensified, with temperature increasing 0.61 °C on the surface and 0.47 °C in the whole water column in continental shelf waters. Water transparency has increased due to a decrease in turbidity anomaly of −0.1 FTU. Since 2013, inshore chlorophyll a concentration remained below the average (−0.15 mg·l−1) and silicates showed a declining trend. The mixed layer depth showed deepening in winter and remained steady in summer. The net surface heat fluxes did not show any trend linked to the local warming, probably due to the influence of incoming offshore waters produced by the interaction between the Northern Current and the submarine canyon. Present regional and global water heating pattern is increasing the stress of highly diverse coastal ecosystems at unprecedented levels, as reported by the literature. The strengthening of the oligotrophic conditions in the study area may also apply as a cautionary warning to similar coastal ecosystems around the world following the global warming trend, The OOCS was initially funded by the Spanish National Research Project OAMMS Ref. CTM2008-03983 (PI. A.C). The research projects ADEPT Ref. CTM2011-23458 Ref. CTM2008-03983 (PI. F.P) and CONECTA Ref. CTM2014-54648-C2−1-R (PI J.B.C) partially contributed to the OOCS operations, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Bazairi, Hocein/0000-0002-1788-0580; Gattuso, Jean-Pierre/0000-0002-4533-4114; Gerovasileiou, Vasilis/0000-0002-9143-7480; Cerrano, Carlo/0000-0001-9580-5546; Turicchia, Eva/0000-0002-8952-9028; Topcu, Nur Eda/0000-0003-2734-2695; Ponti, Massimo/0000-0002-6521-1330; deudero, salud/0000-0001-5584-2801; Ledoux, Jean-Baptiste/0000-0001-8796-6163; Fraschetti, Simonetta/0000-0002-1780-1651; BERTOLINO, Marco/0000-0003-3233-303X; Duarte, Carlos M./0000-0002-1213-1361, WOS: 000499719400001, [No abstract available], postdoctoral contract Juan de la Cierva-Incorporacion [IJCI-2016-29329]; Ministerio de Ciencia, Innovacion y Universidades [PTA2015-10829-I]; Interreg Med Programme [MPA-Adapt 1MED15_3.2_M2_337]; European Regional Development Fund - Foundation Prince Albert II Monaco; European UnionEuropean Union (EU) [689518, FPU15/05457]; Spanish Ministry of EducationSpanish Government [UID/Multi/04423/2013]; FCT - Foundation for Science and TechnologyPortuguese Foundation for Science and Technology; European Regional Development Fund (ERDF)European Union (EU), MV-L was supported by a postdoctoral contract Juan de la Cierva-Incorporacion (IJCI-2016-29329) of Ministerio de Ciencia, Innovacion y Universidades. AI was supported by a Technical staff contract (PTA2015-10829-I) Ayudas Personal Tecnico de Apoyo of Ministerio de Economia y Competitividad (2015). Interreg Med Programme (grant number Project MPA-Adapt 1MED15_3.2_M2_337) 85% cofunded by the European Regional Development Fund, the MIMOSA project funded by the Foundation Prince Albert II Monaco and the European Union's Horizon 2020 research and innovation programme under grant agreement no 689518 (MERCES). DG-G was supported by an FPU grant (FPU15/05457) from the Spanish Ministry of Education. J-BL was partially supported by the Strategic Funding UID/Multi/04423/2013 through national funds provided by FCT - Foundation for Science and Technology and European Regional Development Fund (ERDF), in the framework of the programme PT2020.

13 páginas, 7 figuras, 1 tabla., The differential response of marine populations to climate change remains poorly understood. Here, we combine common garden thermotolerance experiments in aquaria and population genetics to disentangle the factors driving the population response to thermal stress in a temperate habitatforming species: the octocoral Paramuricea clavata. Using eight populations separated from tens of meters to hundreds of kilometers, which were differentially impacted by recent mortality events, we identify 25°C as a critical thermal threshold. After one week of exposure at this temperature, seven of the eight populations were affected by tissue necrosis and after 30 days of exposure at this temperature, the mean % of affected colonies increased gradually from 3 to 97%. We then demonstrate the weak relation between the observed differential phenotypic responses and the local temperature regimes experienced by each population. A significant correlation was observed between these responses and the extent of genetic drift impacting each population. Local adaptation may thus be hindered by genetic drift, which seems to be the main driver of the differential response. Accordingly, conservation measures should promote connectivity and control density erosion in order to limit the impact of genetic drift on marine populations facing climate change., The authors gratefully acknowledge the funding support given by the Alan Program (CC Doctoral Fellowship), by CSIC-Uruguay (Call Programa de pasantías en el exterior 2015) and by the Portuguese Foundation for Science and Technology (Fundação para a Ciència e a Tecnologia; FCT) which funded JBL Postdoctoral grant (SFRH/ BPD/74400/2010). Authors are also grateful to the MEDCHANGE project funded by the Agence Nationale pour la Recherche (ANR) and to the Spanish Ministry of Economy and Competitivity (http://www.mineco.gob.es) through the Biorock (CTM2009-08045), Smart (CGL2012-32194) and CSI-Coral (CGL2013-43106-R). Temperature data series data is part of the regional temperature observation network T-MEDNet (www.t-mednet.org); we thank J.M. Dominici for providing the data for the Réserve Naturelle de Scandola. The authors also thank the staff of Experimental Aquarium Facilities at the Institute of Marine Sciences E. Martinez and M. Delgado for the technical support provided. EC, JG, CL, PL and NT are part of the Marine Conservation research group MEDRECOVER www.medrecover.org (2009 SGR 1174) while RC and MR are part of the Marine Biogeochemistry and Global Change Research group (2014SGR1029) from the Generalitat de Catalunya.

Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring and summer. Here we demonstrate that plankton community respiration evaluated under the continuous daylight conditions present in situ, tends to be higher than that evaluated in the dark. The ratio between community respiration measured in the light (Rlight) and in the dark (Rdark) increased as the 2/3 power of Rlight so that the Rlight:Rdark ratio increased from an average value of 1.37 at the median Rlight measured here (3.62 µmol O2 L−1 d−1) to an average value of 17.56 at the highest Rlight measured here (15.8 µmol O2 L−1 d−1). The role of respiratory processes as a source of CO2 in the Arctic has, therefore, been underestimated and is far more important than previously believed, particularly in the late spring, with 24 h photoperiods, when community respiration rates are highest., ARCTICMET and ATOS, funded by the Spanish Ministry of Economy and Competitiveness (CTM2011-15792-E and POL2006-00550/CTM, respectively), the ATP project funded by the FP-7 of the EU (CTM2009-07781-E), and the CarbonBridge project (no. 226415) funded by the Norwegian Research Council. Work in Young Sound was funded by the Greenland Ecosystem Monitoring (GEM) program.

The neotropical Guayana Highlands (GH) are one of the few remaining pristine environments on Earth, and they host amazing biodiversity with a high degree endemism, especially among vascular plants. Despite the lack of direct human disturbance, GH plants and their communities are threatened with extinction from habitat loss due to global warming (GW). Geographic information systems simulations involving the entire known vascular GH flora (>2430 species) predict potential GW-driven extinctions on the order of 80% by the end of this century, including nearly half of the endemic species. These estimates and the assessment of an environmental impact value for each species led to the hierarchization of plants by their risk of habitat loss and the definition of priority conservation categories. However, the predictions assume that all species will respond to GW by migrating upward and at equal rates, which is unlikely, so current estimates should be considered preliminary and incomplete (although they represent the best that can be done with the existing information). Other potential environmental forcings (i.e., precipitation shifts, an increase in the atmospheric CO2 concentration) and idiosyncratic plant responses (i.e., resistance, phenotypic acclimation, rapid evolution) should also be considered, so detailed eco-physiological studies of the more threatened species are urgently needed. The main obstacles to developing such studies are the remoteness and inaccessibility of the GH and, especially, the difficulty in obtaining official permits for fieldwork. © 2017, Frontiers Research Foundation. All rights reserved.

10 pages, 6 figures, The effects of invasive species on native fauna are understudied in marine ecosystems, even though the impact of introduced species must be taken into consideration for proper conservation and management. The main aim of this study was to investigate the effects of invasive algae on one of the highest diversity assemblages in the Mediterranean, the coralligenous. Two manipulative experiments were designed to study the effects of overgrowth of invasive species on juvenile colonies of the Mediterranean gorgonian Paramuricea clavata, an important structural species in coralligenous assemblages. The experiments were conducted in two French marine protected areas, Port-Cros National Park and Scandola Regional Park, which are separated by hundreds of km and are invaded by Caulerpa racemosa and Womersleyella setacea, respectively. Both invasive species had a strong and consistently negative effect on different components of fitness. This finding was demonstrated by lower survivorship, higher necrosis rates and lower biomass in P. clavata colonies exposed to invasive algal overgrowth compared to the controls. Because invasive species affected the viability of juvenile colonies of P. clavata, we conclude that the persistence of P. clavata populations affected by invasion can be jeopardized, especially in the case of populations already impacted by mass mortalities associated with climate warming, We thank O. Bianchimani for his valuable assistance in the field. Financial support was provided by an EU Reintegration grant (ERG-2009-248252) and a BioRocK project from the MICINN (CTM2009-08045). EC and CL were funded by a Juan de la Cierva Postdoctoral Fellowship. We would like to thank all the staff of the Port Cros National Park and the Scandola Regional Park for permissions and facilities to conduct this study

As a result of climate change, streams are warming and their runoff has been decreasing in most temperate areas. These changes can affect consumers directly by increasing their metabolic rates and modifying their physiology and indirectly by changing the quality of the resources on which organisms depend. In this study, a common stream detritivore (Echinogammarus berilloni Catta) was reared at two temperatures (15 and 20°C) and fed Populus nigra L. leaves that had been conditioned either in an intermittent or permanent reach to evaluate the effects of resource quality and increased temperatures on detritivore performance, stoichiometry and nutrient cycling. The lower quality (i.e., lower protein, soluble carbohydrates and higher C:P and N:P ratios) of leaves conditioned in pools resulted in compensatory feeding and lower nutrient retention capacity by E. berilloni. This effect was especially marked for phosphorus, which was unexpected based on predictions of ecological stoichiometry. When individuals were fed pool-conditioned leaves at warmer temperatures, their growth rates were higher, but consumers exhibited less efficient assimilation and higher mortality. Furthermore, the shifts to lower C:P ratios and higher lipid concentrations in shredder body tissues suggest that structural molecules such as phospholipids are preserved over other energetic C-rich macromolecules such as carbohydrates. These effects on consumer physiology and metabolism were further translated into feces and excreta nutrient ratios. Overall, our results show that the effects of reduced leaf quality on detritivore nutrient retention were more severe at higher temperatures because the shredders were not able to offset their increased metabolism with increased consumption or more efficient digestion when fed pool-conditioned leaves. Consequently, the synergistic effects of impaired food quality and increased temperatures might not only affect the physiology and survival of detritivores but also extend to other trophic compartments through detritivore-mediated nutrient cycling.

[spa] Se presenta una primera aproximación en la diferenciación de la contribución local y global en el incremento de la temperatura del aire en Barcelona. Para ello, se busca determinar la influencia local del área metropolitana de Barcelona en el aumento de la temperatura del aire registrado en el observatorio Fabra, para el periodo 1924-2016, a diferencia del observatorio del Ebro (observatorio de referencia) que presenta solamente la influencia del calentamiento global por ubicarse en una zona rural. La temperatura registrada en el observatorio Fabra presentó una tendencia significativa al incremento durante 1924-2016, incrementándose la temperatura media anual en 1,26 °C. Durante el subperiodo 1972-2016, la temperatura registró una tasa más acelerada en comparación con el subperiodo 1924-1971, coincidiendo el primer subperiodo con los años en que las investigaciones sobre el cambio climático muestran resultados más concluyentes de la influencia antropogénica en el aumento de la temperatura del aire. Considerando dicho subperiodo, el observatorio Fabra registró una influencia térmica local del área metropolitana de Barcelona de 0,0073 °C/año en la temperatura media anual, mientras que 0,0386 °C/año correspondió al aporte del calentamiento global, registrado en el observatorio del Ebro., [eng] This article shows a first approach in the differentiation between the local and global contribution in the increase of the air temperature in Barcelona. Accordingly, the local influence of the Barcelona metropolitan area on the increase of air temperature is assessed by the recorded data at the Fabra observatory for the period 1924-2016; and then, it is compared with the Ebro observatory's (reference observatory), which only presents a global warming influence as it is located in a rural zone. The results show that the temperature recorded in the Fabra observatory has a significant increasing trend; in the term 1924-2016, where the increase of the average monthly temperature was identified in 1,26 °C. The increasing temperature rate recorded for the subperiod 1972-2016 in the Fabra observatory was faster than the one registered for the subperiod 1924-1971, coinciding with the years in which climate change researches have shown more conclusive results of the anthropogenic influence in the increase of air temperature. In this subperiod, the results indicate that the Fabra observatory registered a local thermal influence of the Barcelona metropolitan area which contributes in an increase of 0,0073 °C/year in the average annual temperature, whereas the contribution of the global warming, registered at Ebro observatory, corresponded to an increase of 0,0386 °C/year.

N2O is a GHG of environmental concern. It is generated from the nitrous material contained in wastewater and is the sixth most important contributor to N2O emissions. There is a great variety of methods to quantify the emission of N2O in a wastewater treatment plant (WWTP), which present variants among them, such as predetermined values and operational data of the plants. In this paper, we compared three different methods to quantify the N2O emission in 2015 from WWTP in two metropolitan areas with high population density: Mexico City and the Metropolitan Area of Barcelona (MAB). MAB has advanced treatment plants that remove nutrients from wastewater, and Mexico City has only traditional treatment plants. The N2O emission/inhabitant from WWTPs in MAB (3,214,211 inhabitants served) was 40% lower than the plants in Mexico City (1,806,440 inhabitants served). The MAB emission was 0.009 tCO2e/inhabitant and 0.013 tCO2e/inhabitant in Mexico City; these emission values could be considered statistically different with a risk error of 5%. This difference could be due to the fact that MAB has nutrient removal (42% of inhabitants served), and Mexico City has only traditional treatment plants. The results obtained may be influenced by the default emission factors of each methodology. In addition, per capita protein consumption and water consumption per inhabitant are different parameters that must be considered between these zones to quantify and compare the emission of N2O. The integral methods are closer to the reality of the N2O emission when the operating parameters of each plant and wastewater are considered. There should be more research on the reduction of this GHG in wastewater treatment for a correct quantification of these emissions, and more especially in the estimation of N2O emission factors suitable for each treatment plant and study area.

Analysing the effect water temperature has on Daphnia magna is essential in anticipating the impact climate change will have on this freshwater zooplanktonic keystone species. While many authors have followed this line of research, few have covered an extensive temperature range or complex temperature change scenarios. Global warming is mostly associated with increased extreme temperature events, such as heat waves, as well as earlier and more intense thermal stratification. Both of these events may directly influence D. magna fitness, especially in those populations performing diel vertical migration (DVM). We analysed the effect water temperatures, ranging from 11 to 29°C, have on the filtration capacity (FC) of D. magna, to anticipate the effects of acclimation, temperature change rate (TCR) and potential reversibility of responses to such conditions. Results show that sudden temperature changes have an immediate negative impact on the FC of D. magna and is more severe at higher temperatures and higher TCRs. However, D. magna individuals have shown themselves to be capable of quasi-acclimating to temperatures ranging from 11 to 25°C in around a week and achieving much higher FCs; albeit never reaching the optimal FC achieved at 20°C. That said, 29°C is lethal for D. magna individuals within approximately five days. Finally, non-optimal temperature acclimated individuals can recover maximal FC within 2–4 days of the optimal long-term acclimation temperature (20°C) being re-established, thus proving temperature responses to be reversible This work was supported by the University of Girona funding MPCUdG2016 and by the INNOQUA project from the European Union’s Horizon 2020 research and innovation program (Ares2016-1770486) to MFM, TS, and JC