@article{MesterWillnerFrieleretal.2021,
  author    = {Mester, Benedikt and Willner, Sven N. and Frieler, Katja and Schewe, Jacob},
  title     = {Evaluation of river flood extent simulated with multiple global hydrological models and climate forcings},
  series = {Environmental research letters : ERL / Institute of Physics},
  volume    = {16},
  journal   = {Environmental research letters : ERL / Institute of Physics},
  number    = {9},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1748-9326},
  doi       = {10.1088/1748-9326/ac188d},
  pages     = {15},
  year      = {2021},
  abstract  = {Global flood models (GFMs) are increasingly being used to estimate global-scale societal and economic risks of river flooding. Recent validation studies have highlighted substantial differences in performance between GFMs and between validation sites. However, it has not been systematically quantified to what extent the choice of the underlying climate forcing and global hydrological model (GHM) influence flood model performance. Here, we investigate this sensitivity by comparing simulated flood extent to satellite imagery of past flood events, for an ensemble of three climate reanalyses and 11 GHMs. We study eight historical flood events spread over four continents and various climate zones. For most regions, the simulated inundation extent is relatively insensitive to the choice of GHM. For some events, however, individual GHMs lead to much lower agreement with observations than the others, mostly resulting from an overestimation of inundated areas. Two of the climate forcings show very similar results, while with the third, differences between GHMs become more pronounced. We further show that when flood protection standards are accounted for, many models underestimate flood extent, pointing to deficiencies in their flood frequency distribution. Our study guides future applications of these models, and highlights regions and models where targeted improvements might yield the largest performance gains.},
  language  = {en}
}
@article{RikaniSchewe2021,
  author    = {Rikani, Albano and Schewe, Jacob},
  title     = {Global bilateral migration projections accounting for diasporas, transit and return flows, and poverty constraints},
  series = {Demographic research},
  volume    = {45},
  journal   = {Demographic research},
  publisher = {Max Planck Inst. for Demographic Research},
  address   = {Rostock},
  issn      = {2363-7064},
  doi       = {10.4054/DemRes.2021.45.4},
  pages     = {87 -- 140},
  year      = {2021},
  abstract  = {BACKGROUND Anticipating changes in international migration patterns is useful for demographic studies and for designing policies that support the well-being of those involved. Existing forecasting methods do not account for a number of stylized facts that emerge from large-scale migration observations and theories: existing migrant communities - diasporas - act to lower migration costs and thereby provide a mechanism of self-amplification; return migration and transit migration are important components of global migration flows; and poverty constrains emigration. OBJECTIVE Here we present hindcasts and future projections of international migration that explicitly account for these nonlinear features. METHODS We develop a dynamic model that simulates migration flows by origin, destination, and place of birth. We calibrate the model using recently constructed global datasets of bilateral migration. RESULTS We show that the model reproduces past patterns and trends well based only on initial migrant stocks and changes in national incomes. We then project migration flows under future scenarios of global socioeconomic development. CONCLUSIONS Different assumptions about income levels and between-country inequality lead to markedly different migration trajectories, with migration flows either converging towards net zero if incomes in presently poor countries catch up with the rest of the world; or remaining high or even rising throughout the 21st century if economic development is slower and more unequal. Importantly, diasporas induce significant inertia and sizable return migration flows.},
  language  = {en}
}
@phdthesis{Schewe2011,
  author    = {Schewe, Jacob},
  title     = {Basic physical mechanisms for monsoon failure in past and future climate},
  address   = {Potsdam},
  pages     = {135 S.},
  year      = {2011},
  language  = {en}
}
@article{ScheweLevermann2017,
  author    = {Schewe, Jacob and Levermann, Anders},
  title     = {Non-linear intensification of Sahel rainfall as a possible dynamic response to future warming},
  series = {Earth system dynamics},
  volume    = {8},
  journal   = {Earth system dynamics},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {2190-4979},
  doi       = {10.5194/esd-8-495-2017},
  pages     = {495 -- 505},
  year      = {2017},
  language  = {en}
}
@article{ScheweLevermann2012,
  author    = {Schewe, Jacob and Levermann, Anders},
  title     = {A statistically predictive model for future monsoon failure in India},
  series = {Environmental research letters},
  volume    = {7},
  journal   = {Environmental research letters},
  number    = {4},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1748-9326},
  doi       = {10.1088/1748-9326/7/4/044023},
  pages     = {9},
  year      = {2012},
  abstract  = {Indian monsoon rainfall is vital for a large share of the world's population. Both reliably projecting India's future precipitation and unraveling abrupt cessations of monsoon rainfall found in paleorecords require improved understanding of its stability properties. While details of monsoon circulations and the associated rainfall are complex, full-season failure is dominated by large-scale positive feedbacks within the region. Here we find that in a comprehensive climate model, monsoon failure is possible but very rare under pre-industrial conditions, while under future warming it becomes much more frequent. We identify the fundamental intraseasonal feedbacks that are responsible for monsoon failure in the climate model, relate these to observational data, and build a statistically predictive model for such failure. This model provides a simple dynamical explanation for future changes in the frequency distribution of seasonal mean all-Indian rainfall. Forced only by global mean temperature and the strength of the Pacific Walker circulation in spring, it reproduces the trend as well as the multidecadal variability in the mean and skewness of the distribution, as found in the climate model. The approach offers an alternative perspective on large-scale monsoon variability as the result of internal instabilities modulated by pre-seasonal ambient climate conditions.},
  language  = {en}
}
@misc{ScheweLevermann2017,
  author    = {Schewe, Jacob and Levermann, Anders},
  title     = {Non-linear intensification of Sahel rainfall as a possible dynamic response to future warming},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {630},
  doi       = {10.25932/publishup-41911},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419114},
  pages     = {495 -- 505},
  year      = {2017},
  abstract  = {Projections of the response of Sahel rainfall to future global warming diverge significantly. Meanwhile, paleoclimatic records suggest that Sahel rainfall is capable of abrupt transitions in response to gradual forcing. Here we present climate modeling evidence for the possibility of an abrupt intensification of Sahel rainfall under future climate change. Analyzing 30 coupled global climate model simulations, we identify seven models where central Sahel rainfall increases by 40 to 300\% over the 21st century, owing to a northward expansion of the West African monsoon domain. Rainfall in these models is non-linearly related to sea surface temperature (SST) in the tropical Atlantic and Mediterranean moisture source regions, intensifying abruptly beyond a certain SST warming level. We argue that this behavior is consistent with a self-amplifying dynamic-thermodynamical feedback, implying that the gradual increase in oceanic moisture availability under warming could trigger a sudden intensification of monsoon rainfall far inland of today's core monsoon region.},
  language  = {en}
}
@article{ScheweLevermannCheng2012,
  author    = {Schewe, Jacob and Levermann, Anders and Cheng, Hai},
  title     = {A critical humidity threshold for monsoon transitions},
  series = {Climate of the past : an interactive open access journal of the European Geosciences Union},
  volume    = {8},
  journal   = {Climate of the past : an interactive open access journal of the European Geosciences Union},
  number    = {2},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {1814-9324},
  doi       = {10.5194/cp-8-535-2012},
  pages     = {535 -- 544},
  year      = {2012},
  abstract  = {Monsoon systems around the world are governed by the so-called moisture-advection feedback. Here we show that, in a minimal conceptual model, this feedback implies a critical threshold with respect to the atmospheric specific humidity q(o) over the ocean adjacent to the monsoon region. If q(o) falls short of this critical value q(o)(c), monsoon rainfall over land cannot be sustained. Such a case could occur if evaporation from the ocean was reduced, e.g. due to low sea surface temperatures. Within the restrictions of the conceptual model, we estimate q(o)(c) from present-day reanalysis data for four major monsoon systems, and demonstrate how this concept can help understand abrupt variations in monsoon strength on orbital timescales as found in proxy records.},
  language  = {en}
}
@article{ScheweLevermannMeinshausen2011,
  author    = {Schewe, Jacob and Levermann, Anders and Meinshausen, Malte},
  title     = {Climate change under a scenario near 1.5 degrees C of global warming: monsoon intensification, ocean warming and steric sea level rise},
  series = {Earth system dynamics},
  volume    = {2},
  journal   = {Earth system dynamics},
  number    = {1},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {2190-4979},
  doi       = {10.5194/esd-2-25-2011},
  pages     = {25 -- 35},
  year      = {2011},
  abstract  = {We present climatic consequences of the Representative Concentration Pathways (RCPs) using the coupled climate model CLIMBER-3 alpha, which contains a statistical-dynamical atmosphere and a three-dimensional ocean model. We compare those with emulations of 19 state-of-the-art atmosphere-ocean general circulation models (AOGCM) using MAGICC6. The RCPs are designed as standard scenarios for the forthcoming IPCC Fifth Assessment Report to span the full range of future greenhouse gas (GHG) concentrations pathways currently discussed. The lowest of the RCP scenarios, RCP3-PD, is projected in CLIMBER-3 alpha to imply a maximal warming by the middle of the 21st century slightly above 1.5 degrees C and a slow decline of temperatures thereafter, approaching today's level by 2500. We identify two mechanisms that slow down global cooling after GHG concentrations peak: The known inertia induced by mixing-related oceanic heat uptake; and a change in oceanic convection that enhances ocean heat loss in high latitudes, reducing the surface cooling rate by almost 50\%. Steric sea level rise under the RCP3-PD scenario continues for 200 years after the peak in surface air temperatures, stabilizing around 2250 at 30 cm. This contrasts with around 1.3 m of steric sea level rise by 2250, and 2 m by 2500, under the highest scenario, RCP8.5. Maximum oceanic warming at intermediate depth (300-800 m) is found to exceed that of the sea surface by the second half of the 21st century under RCP3-PD. This intermediate-depth warming persists for centuries even after surface temperatures have returned to present-day values, with potential consequences for marine ecosystems, oceanic methane hydrates, and ice-shelf stability. Due to an enhanced land-ocean temperature contrast, all scenarios yield an intensification of monsoon rainfall under global warming.},
  language  = {en}
}
@article{SchleussnerLissnerFischeretal.2016,
  author    = {Schleussner, Carl-Friedrich and Lissner, Tabea K. and Fischer, Erich M. and Wohland, Jan and Perrette, Mahe and Golly, Antonius and Rogelj, Joeri and Childers, Katelin and Schewe, Jacob and Frieler, Katja and Mengel, Matthias and Hare, William and Schaeffer, Michiel},
  title     = {Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 degrees C and 2 degrees C},
  series = {Earth system dynamics},
  volume    = {7},
  journal   = {Earth system dynamics},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {2190-4979},
  doi       = {10.5194/esd-7-327-2016},
  pages     = {327 -- 351},
  year      = {2016},
  abstract  = {Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 degrees C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 degrees C and 2 degrees C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between a 1.5 degrees C and 2 degrees C warming that are highly relevant for the assessment of dangerous anthropogenic interference with the climate system. For heat-related extremes, the additional 0.5 degrees C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 degrees C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards. This fraction is reduced to about 90\% in 2050 and projected to decline to 70\% by 2100 for a 1.5 degrees C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9\% to 17\% between 1.5 degrees C and 2 degrees C, and the projected lengthening of regional dry spells increases from 7 to 11\%. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high-latitude) regions may benefit, tropical regions like West Africa, South-East Asia, as well as Central and northern South America are projected to face substantial local yield reductions, particularly for wheat and maize. Best estimate sea-level rise projections based on two illustrative scenarios indicate a 50cm rise by 2100 relative to year 2000-levels for a 2 degrees C scenario, and about 10 cm lower levels for a 1.5 degrees C scenario. In a 1.5 degrees C scenario, the rate of sea-level rise in 2100 would be reduced by about 30\% compared to a 2 degrees C scenario. Our findings highlight the importance of regional differentiation to assess both future climate risks and different vulnerabilities to incremental increases in global-mean temperature. The article provides a consistent and comprehensive assessment of existing projections and a good basis for future work on refining our understanding of the difference between impacts at 1.5 degrees C and 2 degrees C warming.},
  language  = {en}
}
@misc{SchleussnerLissnerFischeretal.2016,
  author    = {Schleussner, Carl-Friedrich and Lissner, Tabea Katharina and Fischer, Erich M. and Wohland, Jan and Perrette, Mah{\´e} and Golly, Antonius and Rogelj, Joeri and Childers, Katelin and Schewe, Jacob and Frieler, Katja and Mengel, Matthias and Hare, William and Schaeffer, Michiel},
  title     = {Differential climate impacts for policy-relevant limits to global warming},
  series = {Earth System Dynamics},
  journal   = {Earth System Dynamics},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410258},
  pages     = {25},
  year      = {2016},
  abstract  = {Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 degrees C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 degrees C and 2 degrees C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between a 1.5 degrees C and 2 degrees C warming that are highly relevant for the assessment of dangerous anthropogenic interference with the climate system. For heat-related extremes, the additional 0.5 degrees C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 degrees C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards. This fraction is reduced to about 90\% in 2050 and projected to decline to 70\% by 2100 for a 1.5 degrees C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9\% to 17\% between 1.5 degrees C and 2 degrees C, and the projected lengthening of regional dry spells increases from 7 to 11\%. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high-latitude) regions may benefit, tropical regions like West Africa, South-East Asia, as well as Central and northern South America are projected to face substantial local yield reductions, particularly for wheat and maize. Best estimate sea-level rise projections based on two illustrative scenarios indicate a 50cm rise by 2100 relative to year 2000-levels for a 2 degrees C scenario, and about 10 cm lower levels for a 1.5 degrees C scenario. In a 1.5 degrees C scenario, the rate of sea-level rise in 2100 would be reduced by about 30\% compared to a 2 degrees C scenario. Our findings highlight the importance of regional differentiation to assess both future climate risks and different vulnerabilities to incremental increases in global-mean temperature. The article provides a consistent and comprehensive assessment of existing projections and a good basis for future work on refining our understanding of the difference between impacts at 1.5 degrees C and 2 degrees C warming.},
  language  = {en}
}