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- ItemClimate impacts on human livelihoods: Where uncertainty matters in projections of water availability(München : European Geopyhsical Union, 2014) Lissner, T.K.; Reusser, D.E.; Schewe, J.; Lakes, T.; Kropp, J.P.Climate change will have adverse impacts on many different sectors of society, with manifold consequences for human livelihoods and well-being. However, a systematic method to quantify human well-being and livelihoods across sectors is so far unavailable, making it difficult to determine the extent of such impacts. Climate impact analyses are often limited to individual sectors (e.g. food or water) and employ sector-specific target measures, while systematic linkages to general livelihood conditions remain unexplored. Further, recent multi-model assessments have shown that uncertainties in projections of climate impacts deriving from climate and impact models, as well as greenhouse gas scenarios, are substantial, posing an additional challenge in linking climate impacts with livelihood conditions. This article first presents a methodology to consistently measure what is referred to here as AHEAD (Adequate Human livelihood conditions for wEll-being And Development). Based on a trans-disciplinary sample of concepts addressing human well-being and livelihoods, the approach measures the adequacy of conditions of 16 elements. We implement the method at global scale, using results from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) to show how changes in water availability affect the fulfilment of AHEAD at national resolution. In addition, AHEAD allows for the uncertainty of climate and impact model projections to be identified and differentiated. We show how the approach can help to put the substantial inter-model spread into the context of country-specific livelihood conditions by differentiating where the uncertainty about water scarcity is relevant with regard to livelihood conditions – and where it is not. The results indicate that livelihood conditions are compromised by water scarcity in 34 countries. However, more often, AHEAD fulfilment is limited through other elements. The analysis shows that the water-specific uncertainty ranges of the model output are outside relevant thresholds for AHEAD for 65 out of 111 countries, and therefore do not contribute to the overall uncertainty about climate change impacts on livelihoods. In 46 of the countries in the analysis, water-specific uncertainty is relevant to AHEAD. The AHEAD method presented here, together with first results, forms an important step towards making scientific results more applicable for policy decisions.
- ItemThe Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6(München : European Geopyhsical Union, 2016) O'Neill, Brian C.; Tebaldi, Claudia; van Vuuren, Detlef P.; Eyring, Veronika; Friedlingstein, Pierre; Hurtt, George; Knutti, Reto; Kriegler, Elmar; Lamarque, Jean-Francois; Lowe, Jason; Meehl, Gerald A.; Moss, Richard; Riahi, Keywan; Sanderson, Benjamin M.Projections of future climate change play a fundamental role in improving understanding of the climate system as well as characterizing societal risks and response options. The Scenario Model Intercomparison Project (ScenarioMIP) is the primary activity within Phase 6 of the Coupled Model Intercomparison Project (CMIP6) that will provide multi-model climate projections based on alternative scenarios of future emissions and land use changes produced with integrated assessment models. In this paper, we describe ScenarioMIP's objectives, experimental design, and its relation to other activities within CMIP6. The ScenarioMIP design is one component of a larger scenario process that aims to facilitate a wide range of integrated studies across the climate science, integrated assessment modeling, and impacts, adaptation, and vulnerability communities, and will form an important part of the evidence base in the forthcoming Intergovernmental Panel on Climate Change (IPCC) assessments. At the same time, it will provide the basis for investigating a number of targeted science and policy questions that are especially relevant to scenario-based analysis, including the role of specific forcings such as land use and aerosols, the effect of a peak and decline in forcing, the consequences of scenarios that limit warming to below 2°C, the relative contributions to uncertainty from scenarios, climate models, and internal variability, and long-term climate system outcomes beyond the 21st century. To serve this wide range of scientific communities and address these questions, a design has been identified consisting of eight alternative 21st century scenarios plus one large initial condition ensemble and a set of long-term extensions, divided into two tiers defined by relative priority. Some of these scenarios will also provide a basis for variants planned to be run in other CMIP6-Endorsed MIPs to investigate questions related to specific forcings. Harmonized, spatially explicit emissions and land use scenarios generated with integrated assessment models will be provided to participating climate modeling groups by late 2016, with the climate model simulations run within the 2017–2018 time frame, and output from the climate model projections made available and analyses performed over the 2018–2020 period.
- ItemState-of-the-art global models underestimate impacts from climate extremes([London] : Nature Publishing Group UK, 2019) Schewe, Jacob; Gosling, Simon N.; Reyer, Christopher; Zhao, Fang; Ciais, Philippe; Elliott, Joshua; Francois, Louis; Huber, Veronika; Lotze, Heike K.; Seneviratne, Sonia I.; van Vliet, Michelle T. H.; Vautard, Robert; Wada, Yoshihide; Breuer, Lutz; Büchner, Matthias; Carozza, David A.; Chang, Jinfeng; Coll, Marta; Deryng, Delphine; de Wit, Allard; Eddy, Tyler D.; Folberth, Christian; Frieler, Katja; Friend, Andrew D.; Gerten, Dieter; Gudmundsson, Lukas; Hanasaki, Naota; Ito, Akihiko; Khabarov, Nikolay; Kim, Hyungjun; Lawrence, Peter; Morfopoulos, Catherine; Müller, Christoph; Müller Schmied, Hannes; Orth, René; Ostberg, Sebastian; Pokhrel, Yadu; Pugh, Thomas A. M.; Sakurai, Gen; Satoh, Yusuke; Schmid, Erwin; Stacke, Tobias; Steenbeek, Jeroen; Steinkamp, Jörg; Tang, Qiuhong; Tian, Hanqin; Tittensor, Derek P.; Volkholz, Jan; Wang, Xuhui; Warszawski, LilaGlobal impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. Here we test, for the first time, systematically across many important systems, how well such impact models capture the impacts of extreme climate conditions. Using the 2003 European heat wave and drought as a historical analogue for comparable events in the future, we find that a majority of models underestimate the extremeness of impacts in important sectors such as agriculture, terrestrial ecosystems, and heat-related human mortality, while impacts on water resources and hydropower are overestimated in some river basins; and the spread across models is often large. This has important implications for economic assessments of climate change impacts that rely on these models. It also means that societal risks from future extreme events may be greater than previously thought.
- ItemEnvironmental co-benefits and adverse side-effects of alternative power sector decarbonization strategies([London] : Nature Publishing Group UK, 2019) Luderer, Gunnar; Pehl, Michaja; Arvesen, Anders; Gibon, Thomas; Bodirsky, Benjamin L.; de Boer, Harmen Sytze; Fricko, Oliver; Hejazi, Mohamad; Humpenöder, Florian; Iyer, Gokul; Mima, Silvana; Mouratiadou, Ioanna; Pietzcker, Robert C.; Popp, Alexander; van den Berg, Maarten; van Vuuren, Detlef; Hertwich, Edgar G.A rapid and deep decarbonization of power supply worldwide is required to limit global warming to well below 2 °C. Beyond greenhouse gas emissions, the power sector is also responsible for numerous other environmental impacts. Here we combine scenarios from integrated assessment models with a forward-looking life-cycle assessment to explore how alternative technology choices in power sector decarbonization pathways compare in terms of non-climate environmental impacts at the system level. While all decarbonization pathways yield major environmental co-benefits, we find that the scale of co-benefits as well as profiles of adverse side-effects depend strongly on technology choice. Mitigation scenarios focusing on wind and solar power are more effective in reducing human health impacts compared to those with low renewable energy, while inducing a more pronounced shift away from fossil and toward mineral resource depletion. Conversely, non-climate ecosystem damages are highly uncertain but tend to increase, chiefly due to land requirements for bioenergy.
- ItemDiverging importance of drought stress for maize and winter wheat in Europe([London] : Nature Publishing Group UK, 2018) Webber, Heidi; Ewert, Frank; Olesen, Jørgen E.; Müller, Christoph; Fronzek, Stefan; Ruane, Alex C.; Bourgault, Maryse; Martre, Pierre; Ababaei, Behnam; Bindi, Marco; Ferrise, Roberto; Finger, Robert; Fodor, Nándor; Gabaldón-Leal, Clara; Gaiser, Thomas; Jabloun, Mohamed; Kersebaum, Kurt-Christian; Lizaso, Jon I.; Lorite, Ignacio J.; Manceau, Loic; Moriondo, Marco; Nendel, Claas; RodrÃguez, Alfredo; Ruiz-Ramos, Margarita; Semenov, Mikhail A.; Siebert, Stefan; Stella, Tommaso; Stratonovitch, Pierre; Trombi, Giacomo; Wallach, DanielUnderstanding the drivers of yield levels under climate change is required to support adaptation planning and respond to changing production risks. This study uses an ensemble of crop models applied on a spatial grid to quantify the contributions of various climatic drivers to past yield variability in grain maize and winter wheat of European cropping systems (1984–2009) and drivers of climate change impacts to 2050. Results reveal that for the current genotypes and mix of irrigated and rainfed production, climate change would lead to yield losses for grain maize and gains for winter wheat. Across Europe, on average heat stress does not increase for either crop in rainfed systems, while drought stress intensifies for maize only. In low-yielding years, drought stress persists as the main driver of losses for both crops, with elevated CO2 offering no yield benefit in these years.
- ItemAdaptive responses of animals to climate change are most likely insufficient([London] : Nature Publishing Group UK, 2019) Radchuk, Viktoriia; Reed, Thomas; Teplitsky, Céline; van de Pol, Martijn; Charmantier, Anne; Hassall, Christopher; AdamÃk, Peter; Adriaensen, Frank; Ahola, Markus P.; Arcese, Peter; Avilés, Jesús Miguel; Balbontin, Javier; Berg, Karl S.; Borras, Antoni; Burthe, Sarah; Clobert, Jean; Dehnhard, Nina; de Lope, Florentino; Dhondt, André A.; Dingemanse, Niels J.; Doi, Hideyuki; Eeva, Tapio; Fickel, Joerns; Filella, Iolanda; Fossøy, Frode; Goodenough, Anne E.; Hall, Stephen J. G.; Hansson, Bengt; Harris, Michael; Hasselquist, Dennis; Hickler, Thomas; Joshi, Jasmin; Kharouba, Heather; MartÃnez, Juan Gabriel; Mihoub, Jean-Baptiste; Mills, James A.; Molina-Morales, Mercedes; Moksnes, Arne; Ozgul, Arpat; Parejo, Deseada; Pilard, Philippe; Poisbleau, Maud; Rousset, Francois; Rödel, Mark-Oliver; Scott, David; Senar, Juan Carlos; Stefanescu, Constanti; Stokke, BÃ¥rd G.; Kusano, Tamotsu; Tarka, Maja; Tarwater, Corey E.; Thonicke, Kirsten; Thorley, Jack; Wilting, Andreas; Tryjanowski, Piotr; Merilä, Juha; Sheldon, Ben C.; Pape Møller, Anders; Matthysen, Erik; Janzen, Fredric; Dobson, F. Stephen; Visser, Marcel E.; Beissinger, Steven R.; Courtiol, Alexandre; Kramer-Schadt, StephanieBiological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species. © 2019, The Author(s).
- ItemEurope’s renewable energy directive poised to harm global forests([London] : Nature Publishing Group UK, 2018) Searchinger, Timothy D.; Beringer, Tim; Holtsmark, Bjart; Kammen, Daniel M.; Lambin, Eric F.; Lucht, Wolfgang; Raven, Peter; van Ypersele, Jean-PascalThis comment raises concerns regarding the way in which a new European directive, aimed at reaching higher renewable energy targets, treats wood harvested directly for bioenergy use as a carbon-free fuel. The result could consume quantities of wood equal to all Europe’s wood harvests, greatly increase carbon in the air for decades, and set a dangerous global example.
- ItemImpacts devalue the potential of large-scale terrestrial CO2 removal through biomass plantations(Bristol : IOP Publishing, 2016) Boysen, L.R.; Lucht, W.; Gerten, D.; Heck, V.Large-scale biomass plantations (BPs) are often considered a feasible and safe climate engineering proposal for extracting carbon from the atmosphere and, thereby, reducing global mean temperatures. However, the capacity of such terrestrial carbon dioxide removal (tCDR) strategies and their larger Earth system impacts remain to be comprehensively studied—even more so under higher carbon emissions and progressing climate change. Here, we use a spatially explicit process-based biosphere model to systematically quantify the potentials and trade-offs of a range of BP scenarios dedicated to tCDR, representing different assumptions about which areas are convertible. Based on a moderate CO2 concentration pathway resulting in a global mean warming of 2.5 °C above preindustrial level by the end of this century—similar to the Representative Concentration Pathway (RCP) 4.5—we assume tCDR to be implemented when a warming of 1.5 °C is reached in year 2038. Our results show that BPs can slow down the progression of increasing cumulative carbon in the atmosphere only sufficiently if emissions are reduced simultaneously like in the underlying RCP4.5 trajectory. The potential of tCDR to balance additional, unabated emissions leading towards a business-as-usual pathway alike RCP8.5 is therefore very limited. Furthermore, in the required large-scale applications, these plantations would induce significant trade-offs with food production and biodiversity and exert impacts on forest extent, biogeochemical cycles and biogeophysical properties.
- ItemDecomposing the effects of ocean warming on chlorophyll a concentrations into physically and biologically driven contributions(Bristol : IOP Publishing, 2013) Olonscheck, D.; Hofmann, M.; Worm, B.; Schellnhuber, H.J.Recently compiled observational data suggest a substantial decline in the global median chlorophyll a concentration over the 20th century, a trend that appears to be linked to ocean warming. Several modelling studies have considered changes in the ocean's physical structure as a possible cause, while experimental work supports a biological mechanism, namely an observed increase in zooplankton grazing rate that outpaces phytoplankton production at higher temperatures. Here, we present transient simulations derived from a coupled ocean general circulation and carbon cycle model forced by atmospheric fields under unabated anthropogenic global warming (IPCC SRES A1FI scenario). The simulations account for both physical and biological mechanisms, and can reproduce about one quarter of the observed chlorophyll a decline during the 20th century, when using realistically parameterized temperature sensitivity of zooplankton metabolism (Q10 between 2 and 4) and phytoplankton growth (Q10 ~ 1.9). Therefore, we have employed and re-calibrated the standard ecosystem model which assumes a lower temperature sensitivity of zooplankton grazing (Q10 = 1.1049) by re-scaling phytoplankton growth rates and zooplankton grazing rates. Our model projects a global chlorophyll a decline of >50% by the end of the 21st century. While phytoplankton abundance and chlorophyll a experience pronounced negative effects, primary production and zooplankton concentrations are less sensitive to ocean warming. Although changes in physical structure play an important role, much of the simulated change in chlorophyll a and productivity is related to the uneven temperature sensitivity of the marine ecosystem.
- ItemA multi-model analysis of risk of ecosystem shifts under climate change(Bristol : IOP Publishing, 2013) Warszawski, Lila; Friend, Andrew; Ostberg, Sebastian; Frieler, Katja; Lucht, Wolfgang; Schaphoff, Sibyll; Beerling, David; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B.; Kahana, Ron; Ito, Akihiko; Keribin, Rozenn; Kleidon, Axel; Lomas, Mark; Nishina, Kazuya; Pavlick, Ryan; Rademacher, Tim Tito; Buechner, Matthias; Piontek, Franziska; Schewe, Jacob; Serdeczny, Olivia; Schellnhuber, Hans JoachimClimate change may pose a high risk of change to Earth's ecosystems: shifting climatic boundaries may induce changes in the biogeochemical functioning and structures of ecosystems that render it difficult for endemic plant and animal species to survive in their current habitats. Here we aggregate changes in the biogeochemical ecosystem state as a proxy for the risk of these shifts at different levels of global warming. Estimates are based on simulations from seven global vegetation models (GVMs) driven by future climate scenarios, allowing for a quantification of the related uncertainties. 5–19% of the naturally vegetated land surface is projected to be at risk of severe ecosystem change at 2 ° C of global warming (ΔGMT) above 1980–2010 levels. However, there is limited agreement across the models about which geographical regions face the highest risk of change. The extent of regions at risk of severe ecosystem change is projected to rise with ΔGMT, approximately doubling between ΔGMT = 2 and 3 ° C, and reaching a median value of 35% of the naturally vegetated land surface for ΔGMT = 4 °C. The regions projected to face the highest risk of severe ecosystem changes above ΔGMT = 4 °C or earlier include the tundra and shrublands of the Tibetan Plateau, grasslands of eastern India, the boreal forests of northern Canada and Russia, the savanna region in the Horn of Africa, and the Amazon rainforest.