Earth System Dynamics Discussions最新文献

{"title":"A Methodology for the Spatiotemporal Identification of Compound Hazards: Wind and Precipitation Extremes in Great Britain (1979–2019)","authors":"Aloïs Tilloy, B. Malamud, Amélie Joly-Laugel","doi":"10.5194/esd-2021-52","DOIUrl":"https://doi.org/10.5194/esd-2021-52","url":null,"abstract":"Abstract. Compound hazards are two different natural hazards that impact the same time period and spatial area. Compound hazards can have a footprint that can operates on different spatial and temporal scales than their component single hazards. This article proposes a definition of compound hazards in space and time and presents a methodology for the Spatiotemporal Identification of Compound Hazards (SI–CH). The approach is applied to the analysis of compound precipitation and wind extremes in Great Britain from which we create a database. Hourly precipitation and wind gust values for 1979–2019 are extracted from climate reanalysis (ERA5) within a region including Great Britain and the British channel. Extreme values (above the 99 % quantile) of precipitation and wind gust are clustered with the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, creating clusters for precipitation and for wind gusts. Compound hazard clusters that correspond to the spatial overlap of single hazard clusters during the aggregated duration of the two hazards are then identified. Our ERA5 Hazard Clusters Database (given as a supplement) consists of 18,086 precipitation clusters, 6190 wind clusters, and 4555 compound hazard clusters. The methodology’s ability to identify extreme precipitation and wind events is assessed with a catalogue of 157 significant events (96 extreme precipitation and 61 extreme wind events) that occurred in Great Britain over the period 1979–2019 (also given as a supplement). We find a good agreement between the SI–CH outputs and the catalogue with an overall hit rate (ratio between the number of joint events and the total number of events) of 93.7 %. The spatial variation of hazard intensity within wind, precipitation and compound hazard clusters are then visualised and analysed. The study finds that the SI–CH approach (given as R code in supplement) can accurately identify single and compound hazard events and represent spatial and temporal properties of compound hazard events. We find that compound wind and precipitation extremes, despite occurring on smaller scales than single extremes, can occur on large scales in Great Britain with a decreasing spatial scale when the combined intensity of the hazards increases.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"60 1","pages":"1-45"},"PeriodicalIF":0.0,"publicationDate":"2021-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83922437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying memory and persistence in the atmosphere–land/ocean carbon system","authors":"M. Jonas, R. Bun, I. Ryzha, P. Żebrowski","doi":"10.5194/ESD-2021-27","DOIUrl":"https://doi.org/10.5194/ESD-2021-27","url":null,"abstract":"Abstract. Here we interpret carbon dioxide (CO2) emissions from fossil fuel burning and land use as a global stress-strain experiment. We use the idea of a Maxwell body consisting of elastic and damping (viscous) elements to reflect the overall behaviour of the atmosphere–land/ocean system in response to the continued increase of CO2 emissions between 1850 and 2015. From the standpoint of a global observer, we see that as a consequence of the increase, the CO2 concentration in the atmosphere increases (rather quickly). Concomitantly, the atmosphere warms and expands, while part of the carbon is locked away (rather slowly) in land and oceans, likewise under the influence of global warming. It is not known how reversible and how much out of sync the latter process is in relation to the former. All we know is that the slower process remembers the influence of the faster one which runs ahead. Here we ask three (nontrivial) questions: (1) Can this global-scale memory–Earth’s memory–be quantified? (2) Is Earth’s memory a buffer which is negligently exploited; and in the case that it is even a limited buffer, what is the degree of exploitation? And (3) does Earth’s memory allow its persistence (path dependency) to be quantified? To the best of our knowledge, the answers to these questions are pending. We go beyond textbook knowledge by introducing three parameters that characterise the system: delay time, memory, and persistence. The three parameters depend, ceteris paribus, solely on the system’s characteristic viscoelastic behaviour and allow deeper insights into that system. We find that since 1850, the atmosphere–land/ocean system has been trapped progressively in terms of persistence (i.e., it will become progressively more difficult to strain-relax the system), while its ability to build up memory has been reduced. The ability of a system to build up memory effectively can be understood as its ability to respond still within its natural regime; or, if the build-up of memory is limited, as a measure for system failures globally in the future. Approximately 60 % of Earth’s memory had already been exploited by humankind prior to 1959. We expect system failures globally well before 2050 if the current trend in emissions is not reversed immediately and sustainably.\u0000","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"5 1","pages":"1-41"},"PeriodicalIF":0.0,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75941261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Earth system economics: a biophysical approach to the human component of the Earth system","authors":"E. Galbraith","doi":"10.5194/ESD-12-671-2021","DOIUrl":"https://doi.org/10.5194/ESD-12-671-2021","url":null,"abstract":"Abstract. The study of humans has largely been carried out in isolation from the study of the non-human Earth system. This isolation has encouraged the development of incompatible philosophical, aspirational, and methodological approaches that have proven very difficult to integrate with those used for the non-human remainder of the Earth system. Here, an approach is laid out for the scientific study of the global human system that is intended to facilitate seamless integration with non-human processes by striving for a consistent physical basis, for which the name Earth system economics is proposed. The approach is typified by a foundation on state variables, central among which is the allocation of time amongst activities by human populations, and an orientation towards considering human experience. A framework is elaborated which parses the Earth system into six classes of state variables, including a neural structure class that underpins many essential features of humanity. A working example of the framework is then illustrated with a simple numerical model, considering a global population that is engaged in one of two waking activities: provisioning food or doing something else. The two activities are differentiated by their motivational factors, outcomes on state variables, and associated subjective experience. While the illustrative model is a gross simplification of reality, the results suggest how neural characteristics and subjective experience can emerge from model dynamics. The approach is intended to provide a flexible and widely applicable strategy for understanding the human–Earth system, appropriate for physically based assessments of the past and present, as well as contributing to long-term model projections that are naturally oriented towards improving human well-being.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"162 1","pages":"671-687"},"PeriodicalIF":0.0,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83125197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Space–time dependence of compound hot–dry events in the United States: assessment using a multi-site multi-variable weather generator","authors":"M. Brunner, E. Gilleland, A. Wood","doi":"10.5194/ESD-12-621-2021","DOIUrl":"https://doi.org/10.5194/ESD-12-621-2021","url":null,"abstract":"Abstract. Compound hot and dry events can lead to severe impacts whose severity may depend on their timescale and spatial extent. Despite their potential\u0000importance, the climatological characteristics of these joint events have received little attention regardless of growing interest in climate change\u0000impacts on compound events. Here, we ask how event timescale relates to (1) spatial patterns of compound hot–dry events in the United States,\u0000(2) the spatial extent of compound hot–dry events, and (3) the importance of temperature and precipitation as drivers of compound events. To study\u0000such rare spatial and multivariate events, we introduce a multi-site multi-variable weather generator (PRSim.weather), which enables\u0000generation of a large number of spatial multivariate hot–dry events. We show that the stochastic model realistically simulates distributional and\u0000temporal autocorrelation characteristics of temperature and precipitation at single sites, dependencies between the two variables, spatial\u0000correlation patterns, and spatial heat and meteorological drought indicators and their co-occurrence probabilities. The results of our compound\u0000event analysis demonstrate that (1) the northwestern and southeastern United States are most susceptible to compound hot–dry events independent of\u0000timescale, and susceptibility decreases with increasing timescale; (2) the spatial extent and timescale of compound events are strongly related\u0000to sub-seasonal events (1–3 months) showing the largest spatial extents; and (3) the importance of temperature and precipitation as drivers of\u0000compound events varies with timescale, with temperature being most important at short and precipitation at seasonal timescales. We conclude that timescale is an important factor to be considered in compound event assessments and suggest that climate change impact assessments should consider\u0000several timescales instead of a single timescale when looking at future changes in compound event characteristics. The largest future changes may be expected\u0000for short compound events because of their strong relation to temperature.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"25 1","pages":"621-634"},"PeriodicalIF":0.0,"publicationDate":"2021-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87940495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First assessment of the earth heat inventory within CMIP5 historical simulations","authors":"F. J. Cuesta-Valero, A. García‐García, H. Beltrami, Joel Finnis","doi":"10.5194/ESD-12-581-2021","DOIUrl":"https://doi.org/10.5194/ESD-12-581-2021","url":null,"abstract":"Abstract. The energy imbalance at the top of the atmosphere over the last century has caused an accumulation of heat within the ocean, the continental subsurface, the atmosphere and the cryosphere. Although ∼90  % of the energy gained by the climate system has been stored in the ocean, the other components of the Earth heat inventory cannot be neglected due to their influence on associated climate processes dependent on heat storage, such as sea level rise and permafrost stability. However, there has not been a comprehensive assessment of the heat inventory within global climate simulations yet. Here, we explore the ability of 30 advanced general circulation models (GCMs) from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) to simulate the distribution of heat within the Earth's energy reservoirs for the period 1972–2005 of the Common Era. CMIP5 GCMs simulate an average heat storage of 247±172  ZJ ( 96±4  % of total heat content) in the ocean, 5±9  ZJ ( 2±3  %) in the continental subsurface, 2±3  ZJ ( 1±1  %) in the cryosphere and 2±2  ZJ ( 1±1  %) in the atmosphere. However, the CMIP5 ensemble overestimates the ocean heat content by 83 ZJ and underestimates the continental heat storage by 9 ZJ and the cryosphere heat content by 5 ZJ, in comparison with recent observations. The representation of terrestrial ice masses and the continental subsurface, as well as the response of each model to the external forcing, should be improved in order to obtain better representations of the Earth heat inventory and the partition of heat among climate subsystems in global transient climate simulations.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"43 1","pages":"581-600"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91535153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"23rd Century surprises: Long-term dynamics of the climate and carbon cycle under both high and net negative emissions scenarios","authors":"C. Koven, V. Arora, P. Cadule, R. Fisher, C. Jones, D. Lawrence, Jared Lewis, Keith Lindsey, S. Mathesius, M. Meinshausen, M. Mills, Zebedee R. J. Nicholls, B. Sanderson, N. Swart, W. Wieder, K. Zickfeld","doi":"10.5194/ESD-2021-23","DOIUrl":"https://doi.org/10.5194/ESD-2021-23","url":null,"abstract":"Abstract. Future climate projections from Earth system models (ESMs) typically focus on the timescale of this century. We use a set of four ESMs and one Earth system model of intermediate complexity (EMIC) to explore the dynamics of the Earth’s climate and carbon cycles under contrasting emissions trajectories beyond this century, to the year 2300. The trajectories include a very high emissions, unmitigated fossil-fuel driven scenario, as well as a second mitigation scenario that diverges from the first scenario after 2040 and features an “overshoot”, followed by stabilization of atmospheric CO2 concentrations by means of large net-negative CO2 emissions. In both scenarios, and for all models considered here, the terrestrial system switches from being a net sink to either a neutral state or a net source of carbon, though for different reasons and centered in different geographic regions, depending on both the model and the scenario. The ocean carbon system remains a sink, albeit weakened by climate-carbon feedbacks, in all models under the high emissions scenario, and switches from sink to source in the overshoot scenario. The global mean temperature anomaly generally follows the trajectories of cumulative carbon emissions, except that 23rd-century warming continues after the cessation of carbon emissions in several models, both in the high emissions scenario and in one model in the overshoot scenario. While ocean carbon cycle responses qualitatively agree both in globally integrated and zonal-mean dynamics in both scenarios, the land models qualitatively disagree in zonal-mean dynamics, in the relative roles of vegetation and soil in driving C fluxes, in the response of the sink to CO2, and in the timing of the sink-source transition, particularly in the high emissions scenario. The lack of agreement among land models on the mechanisms and geographic patterns of carbon cycle feedbacks, alongside the potential for lagged physical climate dynamics to cause warming long after CO2 concentrations have stabilized, point to the possibility of surprises in the climate system beyond the 21st century time horizon, even under relatively mitigated global warming scenarios, which should be taken into consideration when setting global climate policy.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"65 9 1","pages":"1-32"},"PeriodicalIF":0.0,"publicationDate":"2021-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84579023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large ensemble climate model simulations: introduction, overview, and future prospects for utilising multiple types of large ensemble","authors":"N. Maher, Sebastian Milinski, R. Ludwig","doi":"10.5194/ESD-12-401-2021","DOIUrl":"https://doi.org/10.5194/ESD-12-401-2021","url":null,"abstract":"Abstract. Single model initial-condition large ensembles (SMILEs) are valuable tools that can be used to investigate the climate system. SMILEs allow scientists to quantify and separate the internal variability of the climate system and its response to external forcing, with different types of SMILEs appropriate to answer different scientific questions. In this editorial we first provide an introduction to SMILEs and an overview of the studies in the special issue “Large Ensemble Climate Model Simulations: Exploring Natural Variability, Change Signals and Impacts”. These studies analyse a range of different types of SMILEs including global climate models (GCMs), regionally downscaled climate models (RCMs), a hydrological model with input from a RCM SMILE, a SMILE with prescribed sea surface temperature (SST) built for event attribution, a SMILE that assimilates observed data, and an initialised regional model. These studies provide novel methods, that can be used with SMILEs. The methods published in this issue include a snapshot empirical orthogonal function analysis used to investigate El Nino–Southern Oscillation teleconnections; the partitioning of future uncertainty into model differences, internal variability, and scenario choices; a weighting scheme for multi-model ensembles that can incorporate SMILEs; and a method to identify the required ensemble size for any given problem. Studies in this special issue also focus on RCM SMILEs, with projections of the North Atlantic Oscillation and its regional impacts assessed over Europe, and an RCM SMILE intercomparison. Finally a subset of studies investigate projected impacts of global warming, with increased water flows projected for future hydrometeorological events in southern Ontario; precipitation projections over central Europe are investigated and found to be inconsistent across models in the Alps, with a continuation of past tendencies in Mid-Europe; and equatorial Asia is found to have an increase in the probability of large fire and drought events under higher levels of warming. These studies demonstrate the utility of different types of SMILEs. In the second part of this editorial we provide a perspective on how three types of SMILEs could be combined to exploit the advantages of each. To do so we use a GCM SMILE and an RCM SMILE with all forcings, as well as a naturally forced GCM SMILE (nat-GCM) over the European domain. We utilise one of the key advantages of SMILEs, precisely separating the forced response and internal variability within an individual model to investigate a variety of simple questions. Broadly we show that the GCM can be used to investigate broad-scale patterns and can be directly compared to the nat-GCM to attribute forced changes to either anthropogenic emissions or volcanoes. The RCM provides high-resolution spatial information of both the forced change and the internal variability around this change at different warming levels. By combining all three ensembles w","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"251 1","pages":"401-418"},"PeriodicalIF":0.0,"publicationDate":"2021-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76310130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biogeochemistry and Physics of the Southern Ocean-Atmosphere System Explored With Data Science","authors":"S. Landwehr, M. Volpi, F. Haumann, C. Robinson, Iris Thurnherr, V. Ferracci, A. Baccarini, Jenny Thomas, I. Gorodetskaya, C. Tatzelt, S. Henning, R. Modini, Heather J. Forrer, Yajuan Lin, N. Cassar, R. Simó, C. Hassler, A. Moallemi, S. Fawcett, Neil Harris, R. Airs, Marzieh H. Derkani, A. Alberello, A. Toffoli, Gang Chen, Pablo Rodríguez Ros, M. Zamanillo, Pau Cortés-Greus, Lei Xue, C. Bolas, K. Leonard, F. Pérez-Cruz, D. Walton, J. Schmale","doi":"10.5194/ESD-2021-16","DOIUrl":"https://doi.org/10.5194/ESD-2021-16","url":null,"abstract":"Abstract. The Southern Ocean is a critical component of Earth’s climate system, but its remoteness makes it challenging to develop a holistic understanding of its processes from the small to the large scale. As a result, our knowledge of this vast region remains largely incomplete. The Antarctic Circumnavigation Expedition (ACE, austral summer 2016/2017) surveyed a large number of variables describing the dynamic state of the ocean and the atmosphere, the freshwater cycle, atmospheric chemistry, ocean biogeochemistry and microbiology. This circumpolar cruise included visits to twelve remote islands, the marginal ice zone, and the Antarctic coast. Here, we use 111 of the observed variables to study the latitudinal gradients, seasonality, shorter term variations, the geographic setting of environmental processes, and interactions between them over the duration of 90 days. To reduce the dimensionality and complexity of the dataset and make the relations between variables interpretable, we applied a sparse Principal Component Analysis (sPCA), which describes environmental processes through 14 latent variables. To derive a robust statistical perspective on these processes and to estimate the uncertainty in the sPCA decomposition, we have developed a bootstrap approach. We identified temporal patterns from diurnal to seasonal cycles, as well as geographical gradients and “hotspots” of interaction. Our results establish connections of oceanic, atmospheric, biological and terrestrial processes in an innovative way, while confirming many well known relations of the Southern Ocean system. More specifically, we identify: the important role of the oceanic circulations, frontal zones, and islands in shaping the nutrient availability that controls biological community composition and productivity; that sea ice predominantly controls sea water salinity, dampens the wave field, and is associated with increased phytoplankton growth and net community productivity possibly due to iron fertilization and reduced light limitation; and clear regional patterns of aerosol characteristics emerged, stressing the role of the sea state, atmospheric chemical processing, as well as source processes near “hotspots” for the availability of cloud condensation nuclei and hence cloud formation. A set of key variables and their combinations, such as the difference between the air and sea surface temperature, atmospheric pressure, sea surface height, geostrophic currents, upper ocean layer light intensity, surface wind speed and relative humidity, played an important role in the majority of latent variables, highlighting their importance for a large variety of processes and the necessity for Earth System Models to represent them adequately. In conclusion, our study highlights the use of sPCA to identify key ocean-atmosphere interactions across physical, chemical, and biological processes and their associated spatio-temporal scales. The sPCA processing code is available as open-access","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"98 1","pages":"1-114"},"PeriodicalIF":0.0,"publicationDate":"2021-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80929288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of a 50-year scaling relating current global energy demands to historically cumulative economic production","authors":"T. Garrett, M. Grasselli, S. Keen","doi":"10.5194/ESD-2021-21","DOIUrl":"https://doi.org/10.5194/ESD-2021-21","url":null,"abstract":"Abstract. Global economic production, or the GDP, has risen steadily relative to world primary energy demands, suggesting technological change is driving a gradual decoupling of society from its resource needs and associated pollution. Here show that in each of the 50 years following 1970 for which reliable data are available, one Exajoule of world energy was consumed to sustain each 5.50 ± 0.21 trillion constant 2019 US dollars, not of yearly production or physical capital, but of running cumulative production summed over human history. The half-century for which this fixed ratio held covers two thirds of historical growth in energy demands, so assuming its persistence, the implication is that society is not in fact decoupling from resource needs. Rather, it can be expected that future environmental impacts will be more strongly guided by past activities, or inertia, than is generally permitted within economic and climate modeling prescriptions that allow for policy to spur more rapid change.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"34 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2021-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79292466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Robust increase of Indian monsoon rainfall and its variability under future warming in CMIP6 models","authors":"A. Katzenberger, J. Schewe, J. Pongratz, A. Levermann","doi":"10.5194/ESD-12-367-2021","DOIUrl":"https://doi.org/10.5194/ESD-12-367-2021","url":null,"abstract":"Abstract. The Indian summer monsoon is an integral part of the global climate system. As its seasonal rainfall plays a crucial role in India's agriculture and shapes many other aspects of life, it affects the livelihood of a fifth of the world's population. It is therefore highly relevant to assess its change under potential future climate change. Global climate models within the Coupled Model Intercomparison Project Phase 5 (CMIP5) indicated a consistent increase in monsoon rainfall and its variability under global warming. Since the range of the results of CMIP5 was still large and the confidence in the models was limited due to partly poor representation of observed rainfall, the updates within the latest generation of climate models in CMIP6 are of interest. Here, we analyze 32 models of the latest CMIP6 exercise with regard to their annual mean monsoon rainfall and its variability. All of these models show a substantial increase in June-to-September (JJAS) mean rainfall under unabated climate change (SSP5-8.5) and most do also for the other three Shared Socioeconomic Pathways analyzed (SSP1-2.6, SSP2-4.5, SSP3-7.0). Moreover, the simulation ensemble indicates a linear dependence of rainfall on global mean temperature with a high agreement between the models independent of the SSP if global warming is the dominant forcing of the monsoon dynamics as it is in the 21st century; the multi-model mean for JJAS projects an increase of 0.33 mm d −1 and 5.3 % per kelvin of global warming. This is significantly higher than in the CMIP5 projections. Most models project that the increase will contribute to the precipitation especially in the Himalaya region and to the northeast of the Bay of Bengal, as well as the west coast of India. Interannual variability is found to be increasing in the higher-warming scenarios by almost all models. The CMIP6 simulations largely confirm the findings from CMIP5 models, but show an increased robustness across models with reduced uncertainties and updated magnitudes towards a stronger increase in monsoon rainfall.","PeriodicalId":11466,"journal":{"name":"Earth System Dynamics Discussions","volume":"118 1","pages":"367-386"},"PeriodicalIF":0.0,"publicationDate":"2021-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75238087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}