Yan-Gui Chen, D. Ji, Qian Zhang, J. Moore, O. Boucher, A. Jones, T. Lurton, M. Mills, U. Niemeier, R. Séférian, S. Tilmes
Abstract. The northern-high-latitude permafrost contains almost twice the carbon content of the atmosphere, and it is widely considered to be a non-linear and tipping element in the earth's climate system under global warming. Solar geoengineering is a means of mitigating temperature rise and reduces some of the associated climate impacts by increasing the planetary albedo; the permafrost thaw is expected to be moderated under slower temperature rise. We analyze the permafrost response as simulated by five fully coupled earth system models (ESMs) and one offline land surface model under four future scenarios; two solar geoengineering scenarios (G6solar and G6sulfur) based on the high-emission scenario (ssp585) restore the global temperature from the ssp585 levels to the moderate-mitigation scenario (ssp245) levels via solar dimming and stratospheric aerosol injection. G6solar and G6sulfur can slow the northern-high-latitude permafrost degradation but cannot restore the permafrost states from ssp585 to those under ssp245. G6solar and G6sulfur tend to produce a deeper active layer than ssp245 and expose more thawed soil organic carbon (SOC) due to robust residual high-latitude warming, especially over northern Eurasia. G6solar and G6sulfur preserve more SOC of 4.6 ± 4.6 and 3.4 ± 4.8 Pg C (coupled ESM simulations) or 16.4 ± 4.7 and 12.3 ± 7.9 Pg C (offline land surface model simulations), respectively, than ssp585 in the northern near-surface permafrost region. The turnover times of SOC decline slower under G6solar and G6sulfur than ssp585 but faster than ssp245. The permafrost carbon–climate feedback is expected to be weaker under solar geoengineering.
{"title":"Northern-high-latitude permafrost and terrestrial carbon response to two solar geoengineering scenarios","authors":"Yan-Gui Chen, D. Ji, Qian Zhang, J. Moore, O. Boucher, A. Jones, T. Lurton, M. Mills, U. Niemeier, R. Séférian, S. Tilmes","doi":"10.5194/esd-14-55-2023","DOIUrl":"https://doi.org/10.5194/esd-14-55-2023","url":null,"abstract":"Abstract. The northern-high-latitude permafrost contains almost twice the carbon\u0000content of the atmosphere, and it is widely considered to be a non-linear and\u0000tipping element in the earth's climate system under global warming. Solar\u0000geoengineering is a means of mitigating temperature rise and reduces some of\u0000the associated climate impacts by increasing the planetary albedo; the\u0000permafrost thaw is expected to be moderated under slower temperature rise.\u0000We analyze the permafrost response as simulated by five fully coupled earth\u0000system models (ESMs) and one offline land surface model under four future\u0000scenarios; two solar geoengineering scenarios (G6solar and G6sulfur) based\u0000on the high-emission scenario (ssp585) restore the global temperature from\u0000the ssp585 levels to the moderate-mitigation scenario (ssp245) levels via\u0000solar dimming and stratospheric aerosol injection. G6solar and G6sulfur can\u0000slow the northern-high-latitude permafrost degradation but cannot restore\u0000the permafrost states from ssp585 to those under ssp245. G6solar and\u0000G6sulfur tend to produce a deeper active layer than ssp245 and expose more\u0000thawed soil organic carbon (SOC) due to robust residual high-latitude\u0000warming, especially over northern Eurasia. G6solar and G6sulfur preserve\u0000more SOC of 4.6 ± 4.6 and 3.4 ± 4.8 Pg C (coupled ESM simulations) or\u000016.4 ± 4.7 and 12.3 ± 7.9 Pg C (offline land surface model\u0000simulations), respectively, than ssp585 in the northern near-surface\u0000permafrost region. The turnover times of SOC decline slower under G6solar\u0000and G6sulfur than ssp585 but faster than ssp245. The permafrost\u0000carbon–climate feedback is expected to be weaker under solar geoengineering.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42037627","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}
Abstract. Circum-Arctic permafrost stores large amounts of frozen carbon that must be maintained to avoid catastrophic climate change. Solar geoengineering has the potential to cool the Arctic surface by increasing planetary albedo but could also reduce tundra productivity. Here, we improve the data-constrained PInc-PanTher model of permafrost carbon storage by including estimates of plant productivity and rhizosphere priming on soil carbon. Six earth system models are used to drive the model, running G6solar (solar dimming) and G6sulfur (stratospheric sulfate aerosols) experiments, which reduce radiative forcing from SSP5-8.5 (no mitigation) to SSP2-4.5 (substantive mitigation) levels. By 2100, simulations indicate a loss of 9.2 ± 0.4 million km2 (mean ± standard error) of permafrost area and 81 ± 8 Pg of soil carbon under the SSP5-8.5 scenario. In comparison, under SSP2-4.5, G6solar, and G6sulfur, permafrost area loss would be mitigated by approximately 39 %, 37 %, and 34 % and soil carbon loss by 42 %, 54 %, and 47 %, respectively, relative to SSP5-8.5. Uncertainties in permafrost soil C loss estimates arise mainly from changes in vegetation productivity. Increased carbon flux from vegetation to soil raises soil C storage, while the priming effects of root exudates lowers it, with a net mitigating effect on soil C loss. Despite model differences, the protective effects of G6solar and G6sulfur on permafrost area and soil C storage are consistent and significant for all ESMs. G6 experiments mitigate ∼ 1/3 of permafrost area loss and halve carbon loss for SSP5-8.5, averting USD 0–70 trillion (mean of USD 20 trillion) in economic losses through reduced permafrost emissions.
{"title":"PInc-PanTher estimates of Arctic permafrost soil carbon under the GeoMIP G6solar and G6sulfur experiments","authors":"Aobo Liu, J. Moore, Yating Chen","doi":"10.5194/esd-14-39-2023","DOIUrl":"https://doi.org/10.5194/esd-14-39-2023","url":null,"abstract":"Abstract. Circum-Arctic permafrost stores large amounts of frozen carbon that must be maintained to avoid catastrophic climate change. Solar geoengineering\u0000has the potential to cool the Arctic surface by increasing planetary albedo but could also reduce tundra productivity. Here, we improve the\u0000data-constrained PInc-PanTher model of permafrost carbon storage by including estimates of plant productivity and rhizosphere priming on soil\u0000carbon. Six earth system models are used to drive the model, running G6solar (solar dimming) and G6sulfur (stratospheric sulfate aerosols)\u0000experiments, which reduce radiative forcing from SSP5-8.5 (no mitigation) to SSP2-4.5 (substantive mitigation) levels. By 2100, simulations indicate\u0000a loss of 9.2 ± 0.4 million km2 (mean ± standard error) of permafrost area and 81 ± 8 Pg of soil carbon under the\u0000SSP5-8.5 scenario. In comparison, under SSP2-4.5, G6solar, and G6sulfur, permafrost area loss would be mitigated by approximately 39 %, 37 %,\u0000and 34 % and soil carbon loss by 42 %, 54 %, and 47 %, respectively, relative to SSP5-8.5. Uncertainties in permafrost soil\u0000C loss estimates arise mainly from changes in vegetation productivity. Increased carbon flux from vegetation to soil raises soil\u0000C storage, while the priming effects of root exudates lowers it, with a net mitigating effect on soil C loss. Despite model\u0000differences, the protective effects of G6solar and G6sulfur on permafrost area and soil C storage are consistent and significant for all\u0000ESMs. G6 experiments mitigate ∼ 1/3 of permafrost area loss and halve carbon loss for SSP5-8.5, averting USD 0–70 trillion (mean of USD 20 trillion) in\u0000economic losses through reduced permafrost emissions.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47785569","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}
Abstract. In climatological research, the evaluation of climate models is one of the central research subjects. As an expression of large-scale dynamical processes, global teleconnections play a major role in interannual to decadal climate variability. Their realistic representation is an indispensable requirement for the simulation of climate change, both natural and anthropogenic. Therefore, the evaluation of global teleconnections is of utmost importance when assessing the physical plausibility of climate projections. We present an application of the graph-theoretical analysis tool δ-MAPS, which constructs complex networks on the basis of spatio-temporal gridded data sets, here sea surface temperature and geopotential height at 500 hPa. Complex networks complement more traditional methods in the analysis of climate variability, like the classification of circulation regimes or empirical orthogonal functions, assuming a new non-linear perspective. While doing so, a number of technical tools and metrics, borrowed from different fields of data science, are implemented into the δ-MAPS framework in order to overcome specific challenges posed by our target problem. Those are trend empirical orthogonal functions (EOFs), distance correlation and distance multicorrelation, and the structural similarity index. δ-MAPS is a two-stage algorithm. In the first place, it assembles grid cells with highly coherent temporal evolution into so-called domains. In a second step, the teleconnections between the domains are inferred by means of the non-linear distance correlation. We construct 2 unipartite and 1 bipartite network for 22 historical CMIP6 climate projections and 2 century-long coupled reanalyses (CERA-20C and 20CRv3). Potential non-stationarity is taken into account by the use of moving time windows. The networks derived from projection data are compared to those from reanalyses. Our results indicate that no single climate projection outperforms all others in every aspect of the evaluation. But there are indeed models which tend to perform better/worse in many aspects. Differences in model performance are generally low within the geopotential height unipartite networks but higher in sea surface temperature and most pronounced in the bipartite network representing the interaction between ocean and atmosphere.
{"title":"Evaluation of global teleconnections in CMIP6 climate projections using complex networks","authors":"C. Dalelane, Kristina Winderlich, A. Walter","doi":"10.5194/esd-14-17-2023","DOIUrl":"https://doi.org/10.5194/esd-14-17-2023","url":null,"abstract":"Abstract. In climatological research, the evaluation of climate models is one of the central research subjects. As an expression of large-scale dynamical processes, global teleconnections play a major role in interannual to decadal climate variability. Their realistic representation is an indispensable requirement for the simulation of climate change, both natural and anthropogenic. Therefore, the evaluation of global teleconnections is of utmost importance when assessing the physical plausibility of climate projections. We present an application of the graph-theoretical analysis tool δ-MAPS, which constructs complex networks on the basis of spatio-temporal gridded data sets, here sea surface temperature and geopotential height at 500 hPa. Complex networks complement more traditional methods in the analysis of climate variability, like the classification of circulation regimes or empirical orthogonal functions, assuming a new non-linear perspective. While doing so, a number of technical tools and metrics, borrowed from different fields of data science, are implemented into the δ-MAPS framework in order to overcome specific challenges posed by our target problem. Those are trend empirical orthogonal functions (EOFs), distance correlation and distance multicorrelation, and the structural similarity index. δ-MAPS is a two-stage algorithm. In the first place, it assembles grid cells with highly coherent temporal evolution into so-called domains. In a second step, the teleconnections between the domains are inferred by means of the non-linear distance correlation. We construct 2 unipartite and 1 bipartite network for 22 historical CMIP6 climate projections and 2 century-long coupled reanalyses (CERA-20C and 20CRv3). Potential non-stationarity is taken into account by the use of moving time windows. The networks derived from projection data are compared to those from reanalyses. Our results indicate that no single climate projection outperforms all others in every aspect of the evaluation. But there are indeed models which tend to perform better/worse in many aspects. Differences in model performance are generally low within the geopotential height unipartite networks but higher in sea surface temperature and most pronounced in the bipartite network representing the interaction between ocean and atmosphere.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42362484","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}
Han Qiu, D. Hao, Yelu Zeng, Xuesong Zhang, M. Chen
Abstract. Climate warming is accelerating the changes in the global terrestrial ecosystems and particularly those in the northern high latitudes (NHLs; poleward of 50∘ N) and rendering the land–atmosphere carbon exchange highly uncertain. The Coupled Model Intercomparison Project Phase 6 (CMIP6) employs the most updated climate models to estimate terrestrial ecosystem carbon dynamics driven by a new set of socioeconomic and climate change pathways. By analyzing the future (2015–2100) carbon fluxes estimated by 10 CMIP6 models, we quantitatively evaluated the projected magnitudes, trends, and uncertainties in the global and NHL carbon fluxes under four scenarios plus the role of NHLs in the global terrestrial ecosystem carbon dynamics. Overall, the models suggest that the global and NHL terrestrial ecosystems will be consistent carbon sinks in the future, and the magnitude of the carbon sinks is projected to be larger under scenarios with higher radiative forcing. By the end of this century, the models on average estimate the NHL net ecosystem productivity (NEP) as 0.54 ± 0.77, 1.01 ± 0.98, 0.97 ± 1.62, and 1.05 ± 1.83 Pg C yr−1 under SSP126, SSP245, SSP370, and SSP585, respectively. The uncertainties are not substantially reduced compared with earlier results, e.g., the Coupled Climate–Carbon Cycle Model Intercomparison Project (C4MIP). Although NHLs contribute a small fraction of the global carbon sink (∼ 13 %), the relative uncertainties in NHL NEP are much larger than the global level. Our results provide insights into future carbon flux evolutions under future scenarios and highlight the urgent need to constrain the large uncertainties associated with model projections for making better climate mitigation strategies.
摘要气候变暖正在加速全球陆地生态系统的变化，特别是在北部高纬度地区(nhl;向极(50°N)，使陆地与大气的碳交换极不确定。耦合模式比对项目第6阶段(CMIP6)采用最新的气候模式来估算由一系列新的社会经济和气候变化途径驱动的陆地生态系统碳动态。通过分析10个CMIP6模式估算的未来(2015-2100)碳通量，我们定量评估了四种情景下全球和NHL碳通量的预估幅度、趋势和不确定性，以及NHL在全球陆地生态系统碳动态中的作用。总体而言，这些模式表明，未来全球和nhl陆地生态系统将是一致的碳汇，并且在辐射强迫较高的情景下，碳汇的规模预计会更大。到本世纪末，在SSP126、SSP245、SSP370和SSP585条件下，NHL净生态系统生产力(NEP)均值分别为0.54±0.77、1.01±0.98、0.97±1.62和1.05±1.83 Pg C yr - 1。与以前的结果相比，不确定性并没有显著降低。，耦合气候-碳循环模式比对项目(C4MIP)。虽然NHL贡献了全球碳汇的一小部分(约13%)，但NHL NEP的相对不确定性远远大于全球水平。我们的研究结果提供了对未来情景下碳通量演变的见解，并强调了迫切需要约束与模式预测相关的巨大不确定性，从而制定更好的气候减缓战略。
{"title":"Global and northern-high-latitude net ecosystem production in the 21st century from CMIP6 experiments","authors":"Han Qiu, D. Hao, Yelu Zeng, Xuesong Zhang, M. Chen","doi":"10.5194/esd-14-1-2023","DOIUrl":"https://doi.org/10.5194/esd-14-1-2023","url":null,"abstract":"Abstract. Climate warming is accelerating the changes in the global\u0000terrestrial ecosystems and particularly those in the northern high latitudes\u0000(NHLs; poleward of 50∘ N) and rendering the land–atmosphere\u0000carbon exchange highly uncertain. The Coupled Model Intercomparison Project\u0000Phase 6 (CMIP6) employs the most updated climate models to estimate\u0000terrestrial ecosystem carbon dynamics driven by a new set of socioeconomic\u0000and climate change pathways. By analyzing the future (2015–2100) carbon\u0000fluxes estimated by 10 CMIP6 models, we quantitatively evaluated the\u0000projected magnitudes, trends, and uncertainties in the global and NHL carbon\u0000fluxes under four scenarios plus the role of NHLs in the global terrestrial\u0000ecosystem carbon dynamics. Overall, the models suggest that the global and\u0000NHL terrestrial ecosystems will be consistent carbon sinks in the future,\u0000and the magnitude of the carbon sinks is projected to be larger under\u0000scenarios with higher radiative forcing. By the end of this century, the\u0000models on average estimate the NHL net ecosystem productivity (NEP) as\u00000.54 ± 0.77, 1.01 ± 0.98, 0.97 ± 1.62, and 1.05 ± 1.83 Pg C yr−1 under SSP126, SSP245, SSP370, and SSP585, respectively. The\u0000uncertainties are not substantially reduced compared with earlier results,\u0000e.g., the Coupled Climate–Carbon Cycle Model Intercomparison Project\u0000(C4MIP). Although NHLs contribute a small fraction of the global carbon sink\u0000(∼ 13 %), the relative uncertainties in NHL NEP are much\u0000larger than the global level. Our results provide insights into future\u0000carbon flux evolutions under future scenarios and highlight the urgent need\u0000to constrain the large uncertainties associated with model projections for\u0000making better climate mitigation strategies.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46536681","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}
Pub Date : 2022-12-19DOI: 10.5194/esd-13-1715-2022
B. Sanderson, M. Rugenstein
Abstract. To estimate equilibrium climate sensitivity from a simulation where a step change in carbon dioxide concentrations is imposed, a common approach is to linearly extrapolate temperatures as a function of top-of-atmosphere energetic imbalance to estimate the equilibrium state (“effective climate sensitivity”). In this study, we find that this estimate may be biased in some models due to state-dependent energetic leaks. Using an ensemble of multi-millennial simulations of climate model response to a constant forcing, we estimate equilibrium climate sensitivity through Bayesian calibration of simple climate models which allow for responses from subdecadal to multi-millennial timescales. Results suggest potential biases in effective climate sensitivity in the case of particular models where radiative tendencies imply energetic imbalances which differ between pre-industrial and quadrupled CO2 states, whereas for other models even multi-thousand-year experiments are insufficient to predict the equilibrium state. These biases draw into question the utility of effective climate sensitivity as a metric of warming response to greenhouse gases and underline the requirement for operational climate sensitivity experiments on millennial timescales to better understand committed warming following a stabilization of greenhouse gases.
{"title":"Potential for bias in effective climate sensitivity from state-dependent energetic imbalance","authors":"B. Sanderson, M. Rugenstein","doi":"10.5194/esd-13-1715-2022","DOIUrl":"https://doi.org/10.5194/esd-13-1715-2022","url":null,"abstract":"Abstract. To estimate equilibrium climate sensitivity from a simulation where a step change in carbon dioxide concentrations is imposed, a common approach is to linearly extrapolate temperatures as a function of top-of-atmosphere energetic imbalance to estimate the equilibrium state (“effective climate sensitivity”). In this study, we find that this estimate may be biased in some models due to state-dependent energetic leaks. Using an ensemble of multi-millennial simulations of climate model response to a constant forcing, we estimate equilibrium climate sensitivity through Bayesian calibration of simple climate models which allow for responses from subdecadal to multi-millennial timescales. Results suggest potential biases in effective climate sensitivity in the case of particular models where radiative tendencies imply energetic imbalances which differ between pre-industrial and quadrupled CO2 states, whereas for other models even multi-thousand-year experiments are insufficient to predict the equilibrium state. These biases draw into question the utility of effective climate sensitivity as a metric of warming response to greenhouse gases and underline the requirement for operational climate sensitivity experiments on millennial timescales to better understand committed warming following a stabilization of greenhouse gases.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45661468","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}
Pub Date : 2022-12-08DOI: 10.5194/esd-13-1689-2022
S. Philip, S. Kew, G. J. van Oldenborgh, F. Anslow, S. Seneviratne, R. Vautard, D. Coumou, K. Ebi, J. Arrighi, Roop K. Singh, M. V. van Aalst, Carolina Pereira Marghidan, M. Wehner, Wenchang Yang, Sihan Li, D. Schumacher, M. Hauser, R. Bonnet, Linh N. Luu, F. Lehner, N. Gillett, Jordis S. Tradowsky, G. Vecchi, Christopher E. Rodell, R. Stull, Rosie Howard, F. Otto
Abstract. Towards the end of June 2021, temperature records were broken by several degrees Celsius in several cities in the Pacific Northwest areas of the US and Canada, leading to spikes in sudden deaths and sharp increases in emergency calls and hospital visits for heat-related illnesses. Here we present a multi-model, multi-method attribution analysis to investigate the extent to which human-induced climate change has influenced the probability and intensity of extreme heat waves in this region. Based on observations, modelling and a classical statistical approach, the occurrence of a heat wave defined as the maximum daily temperature (TXx) observed in the area 45–52∘ N, 119–123∘ W, was found to be virtually impossible without human-caused climate change. The observed temperatures were so extreme that they lay far outside the range of historical temperature observations. This makes it hard to state with confidence how rare the event was. Using a statistical analysis that assumes that the heat wave is part of the same distribution as previous heat waves in this region led to a first-order estimation of the event frequency of the order of once in 1000 years under current climate conditions. Using this assumption and combining the results from the analysis of climate models and weather observations, we found that such a heat wave event would be at least 150 times less common without human-induced climate change. Also, this heat wave was about 2 ∘C hotter than a 1-in-1000-year heat wave would have been in 1850–1900, when global mean temperatures were 1.2 ∘C cooler than today. Looking into the future, in a world with 2 ∘C of global warming (0.8 ∘C warmer than today), a 1000-year event would be another degree hotter. Our results provide a strong warning: our rapidly warming climate is bringing us into uncharted territory with significant consequences for health, well-being and livelihoods. Adaptation and mitigation are urgently needed to prepare societies for a very different future.
{"title":"Rapid attribution analysis of the extraordinary heat wave on the Pacific coast of the US and Canada in June 2021","authors":"S. Philip, S. Kew, G. J. van Oldenborgh, F. Anslow, S. Seneviratne, R. Vautard, D. Coumou, K. Ebi, J. Arrighi, Roop K. Singh, M. V. van Aalst, Carolina Pereira Marghidan, M. Wehner, Wenchang Yang, Sihan Li, D. Schumacher, M. Hauser, R. Bonnet, Linh N. Luu, F. Lehner, N. Gillett, Jordis S. Tradowsky, G. Vecchi, Christopher E. Rodell, R. Stull, Rosie Howard, F. Otto","doi":"10.5194/esd-13-1689-2022","DOIUrl":"https://doi.org/10.5194/esd-13-1689-2022","url":null,"abstract":"Abstract. Towards the end of June 2021, temperature records were broken by several degrees Celsius in several cities in the Pacific Northwest areas of the US and Canada, leading to spikes in sudden deaths and sharp increases in emergency calls and hospital visits for heat-related illnesses. Here we present a multi-model, multi-method attribution analysis to investigate the extent to which human-induced climate change has influenced the probability and intensity of extreme heat waves in this region. Based on observations, modelling and a classical statistical approach, the occurrence of a heat wave defined as the maximum daily temperature (TXx) observed in the area 45–52∘ N, 119–123∘ W, was found to be virtually impossible without human-caused climate change. The observed temperatures were so extreme that they lay far outside the range of historical temperature observations. This makes it hard to state with confidence how rare the event was. Using a statistical analysis that assumes that the heat wave is part of the same distribution as previous heat waves in this region led to a first-order estimation of the event frequency of the order of once in 1000 years under current climate conditions. Using this assumption and combining the results from the analysis of climate models and weather observations, we found that such a heat wave event would be at least 150 times less common without human-induced climate change. Also, this heat wave was about 2 ∘C hotter than a 1-in-1000-year heat wave would have been in 1850–1900, when global mean temperatures were 1.2 ∘C cooler than today. Looking into the future, in a world with 2 ∘C of global warming (0.8 ∘C warmer than today), a 1000-year event would be another degree hotter. Our results provide a strong warning: our rapidly warming climate is bringing us into uncharted territory with significant consequences for health, well-being and livelihoods. Adaptation and mitigation are urgently needed to prepare societies for a very different future.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41877785","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}
Pub Date : 2022-11-23DOI: 10.5194/esd-13-1641-2022
J. Schwinger, A. Asaadi, N. Steinert, Hanna Lee
Abstract. Anthropogenic CO2 emissions cause irreversible climate change on centennial to millennial timescales, yet current mitigation efforts are insufficient to limit global warming to a level that is considered safe. Carbon dioxide removal (CDR) has been suggested as an option to partially reverse climate change and to return the Earth system to a less dangerous state after a period of temperature overshoot. Whether or to what extent such partial reversal of climate change under CDR would happen is, next to socio-economic feasibility and sustainability, key to assessing CDR as a mitigation option. Here, we use a state-of-the-art Earth system model that includes a representation of permafrost carbon to investigate the reversibility of the Earth system after overshoots of different durations and magnitudes in idealized simulations. We find that atmospheric CO2 concentrations are slightly lower after an overshoot, compared to a reference simulation without overshoot, due to a near-perfect compensation of carbon losses from land by increased ocean carbon uptake during the overshoot periods. The legacy of an overshoot is, on a centennial timescale, indiscernible (within natural variability) from a reference case without overshoot for many aspects of the Earth system including global average surface temperature, marine and terrestrial productivity, strength of the Atlantic meridional overturning circulation, surface ocean pH, surface O2 concentration, and permafrost extent, except in the most extreme overshoot scenario considered in this study. Consistent with previous studies, we find irreversibility in permafrost carbon and deep ocean properties like seawater temperature, pH, and O2 concentrations. We do not find any indication of tipping points or self-reinforcing feedbacks that would put the Earth system on a significantly different trajectory after an overshoot. Hence, the effectiveness of CDR in partially reversing large-scale patterns of climate change might not be the main issue of CDR but rather the impacts and risks that would occur during the period of elevated temperatures during the overshoot.
{"title":"Emit now, mitigate later? Earth system reversibility under overshoots of different magnitudes and durations","authors":"J. Schwinger, A. Asaadi, N. Steinert, Hanna Lee","doi":"10.5194/esd-13-1641-2022","DOIUrl":"https://doi.org/10.5194/esd-13-1641-2022","url":null,"abstract":"Abstract. Anthropogenic CO2 emissions cause irreversible climate change\u0000on centennial to millennial timescales, yet current mitigation efforts are\u0000insufficient to limit global warming to a level that is considered safe.\u0000Carbon dioxide removal (CDR) has been suggested as an option to partially\u0000reverse climate change and to return the Earth system to a less dangerous\u0000state after a period of temperature overshoot. Whether or to what extent\u0000such partial reversal of climate change under CDR would happen is, next to\u0000socio-economic feasibility and sustainability, key to assessing CDR as a\u0000mitigation option. Here, we use a state-of-the-art Earth system model that\u0000includes a representation of permafrost carbon to investigate the\u0000reversibility of the Earth system after overshoots of different durations and\u0000magnitudes in idealized simulations. We find that atmospheric CO2\u0000concentrations are slightly lower after an overshoot, compared to a\u0000reference simulation without overshoot, due to a near-perfect compensation\u0000of carbon losses from land by increased ocean carbon uptake during the\u0000overshoot periods. The legacy of an overshoot is, on a centennial timescale, indiscernible (within natural variability) from a reference case\u0000without overshoot for many aspects of the Earth system including global\u0000average surface temperature, marine and terrestrial productivity, strength\u0000of the Atlantic meridional overturning circulation, surface ocean pH,\u0000surface O2 concentration, and permafrost extent, except in the most extreme overshoot scenario considered in this study. Consistent with\u0000previous studies, we find irreversibility in permafrost carbon and deep\u0000ocean properties like seawater temperature, pH, and O2 concentrations. We do not find any indication of tipping points or self-reinforcing feedbacks that would put the Earth system on a significantly different trajectory after an overshoot. Hence, the effectiveness of CDR in partially reversing large-scale patterns of climate change might not be the main issue of CDR but rather the impacts and risks that would occur during the period of elevated temperatures during the overshoot.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42294310","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}
Pub Date : 2022-11-18DOI: 10.5194/esd-13-1625-2022
Jia-ling Wang, J. Moore, Liyun Zhao, Chao Yue, Z. Di
Abstract. We use four Earth system models (ESMs) to simulate climate under the modest greenhouse emissions RCP4.5 (Representative Concentration Pathway), the “business-as-usual” RCP8.5 and the stratospheric aerosol injection G4 geoengineering scenarios. These drive a 10 km resolution dynamically downscaled model (Weather Research and Forecasting, WRF) and a statistically bias-corrected (Inter-Sectoral Impact Model Intercomparison Project, ISIMIP) and downscaled simulation in a 450×330 km domain containing the Beijing Province, ranging from 2000 m elevation to sea level. The 1980s simulations of surface temperatures, humidities and wind speeds using statistical bias correction make for a better estimate of mean climate determined by ERA5 reanalysis data than does the WRF simulation. However correcting the WRF output with quantile delta mapping bias correction removes the offsets in mean state and results in WRF better reproducing observations over 2007–2017 than ISIMIP bias correction. The WRF simulations consistently show 0.5 ∘C higher mean annual temperatures than from ISIMIP due both to the better resolved city centres and also to warmer winter temperatures. In the 2060s WRF produces consistently larger spatial ranges of surface temperatures, humidities and wind speeds than ISIMIP downscaling across the Beijing Province for all three future scenarios. The WRF and ISIMIP methods produce very similar spatial patterns of temperature with G4 and are always cooler than RCP4.5 and RCP8.5, by a slightly larger amount with ISIMIP than WRF. Humidity scenario differences vary greatly between ESMs, and hence ISIMIP downscaling, while for WRF the results are far more consistent across ESMs and show only small changes between scenarios. Mean wind speeds show similarly small changes over the domain, although G4 is significantly windier under WRF than either RCP scenario.
{"title":"Regional dynamical and statistical downscaling temperature, humidity and wind speed for the Beijing region under stratospheric aerosol injection geoengineering","authors":"Jia-ling Wang, J. Moore, Liyun Zhao, Chao Yue, Z. Di","doi":"10.5194/esd-13-1625-2022","DOIUrl":"https://doi.org/10.5194/esd-13-1625-2022","url":null,"abstract":"Abstract. We use four Earth system models (ESMs) to simulate climate\u0000under the modest greenhouse emissions RCP4.5 (Representative Concentration Pathway), the “business-as-usual”\u0000RCP8.5 and the stratospheric aerosol injection G4 geoengineering scenarios.\u0000These drive a 10 km resolution dynamically downscaled model (Weather Research and Forecasting, WRF) and a\u0000statistically bias-corrected (Inter-Sectoral Impact Model Intercomparison Project, ISIMIP) and downscaled simulation in a\u0000450×330 km domain containing the Beijing Province, ranging from\u00002000 m elevation to sea level. The 1980s simulations of surface\u0000temperatures, humidities and wind speeds using statistical bias correction\u0000make for a better estimate of mean climate determined by ERA5 reanalysis\u0000data than does the WRF simulation. However correcting the WRF output with\u0000quantile delta mapping bias correction removes the offsets in mean state and\u0000results in WRF better reproducing observations over 2007–2017 than ISIMIP\u0000bias correction. The WRF simulations consistently show 0.5 ∘C higher\u0000mean annual temperatures than from ISIMIP due both to the better resolved\u0000city centres and also to warmer winter temperatures. In the 2060s WRF\u0000produces consistently larger spatial ranges of surface temperatures,\u0000humidities and wind speeds than ISIMIP downscaling across the Beijing\u0000Province for all three future scenarios. The WRF and ISIMIP methods produce very\u0000similar spatial patterns of temperature with G4 and are always cooler than\u0000RCP4.5 and RCP8.5, by a slightly larger amount with ISIMIP than WRF.\u0000Humidity scenario differences vary greatly between ESMs, and hence ISIMIP\u0000downscaling, while for WRF the results are far more consistent across ESMs\u0000and show only small changes between scenarios. Mean wind speeds show\u0000similarly small changes over the domain, although G4 is significantly\u0000windier under WRF than either RCP scenario.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43834072","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}
Pub Date : 2022-11-17DOI: 10.5194/esd-13-1611-2022
Yiyu Zheng, M. Rugenstein, P. Pieper, Goratz Beobide‐Arsuaga, J. Baehr
Abstract. Responses of El Niño–Southern Oscillation (ENSO) to global warming remain uncertain, which challenges ENSO forecasts in a warming climate. We investigate changes in ENSO characteristics and predictability in idealized simulations with quadrupled CO2 forcing from seven general circulation models. Comparing the warmer climate to control simulations, ENSO variability weakens, with the neutral state lasting longer, while active ENSO states last shorter and skew to favor the La Niña state. The 6-month persistence-assessed ENSO predictability slightly reduces in five models and increases in two models under the warming condition. While the overall changes in ENSO predictability are insignificant, we find significant relationships between changes in predictability and intensity, duration, and skewness of the three individual ENSO states. The maximal contribution to changes in the predictability of El Niño, La Niña and neutral states stems from changes in skewness and events' duration. Our findings show that a robust and significant decrease in ENSO characteristics does not imply a similar change in ENSO predictability in a warmer climate. This could be due to model deficiencies in ENSO dynamics and limitations in the persistence model when predicting ENSO.
{"title":"El Niño–Southern Oscillation (ENSO) predictability in equilibrated warmer climates","authors":"Yiyu Zheng, M. Rugenstein, P. Pieper, Goratz Beobide‐Arsuaga, J. Baehr","doi":"10.5194/esd-13-1611-2022","DOIUrl":"https://doi.org/10.5194/esd-13-1611-2022","url":null,"abstract":"Abstract. Responses of El Niño–Southern Oscillation (ENSO) to global warming remain uncertain, which challenges ENSO forecasts in a warming climate. We investigate changes in ENSO characteristics and predictability in idealized simulations with quadrupled CO2 forcing from seven general circulation models. Comparing the warmer climate to control simulations, ENSO variability weakens, with the neutral state lasting longer, while active ENSO states last shorter and skew to favor the La Niña state. The 6-month persistence-assessed ENSO predictability slightly reduces in five models and increases in two models under the warming condition. While the overall changes in ENSO predictability are insignificant, we find significant relationships between changes in predictability and intensity, duration, and skewness of the three individual ENSO states. The maximal contribution to changes in the predictability of El Niño, La Niña and neutral states stems from changes in skewness and events' duration. Our findings show that a robust and significant decrease in ENSO characteristics does not imply a similar change in ENSO predictability in a warmer climate. This could be due to model deficiencies in ENSO dynamics and limitations in the persistence model when predicting ENSO.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43242870","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}
Abstract. The South Asian and East Asian summer monsoons are globally significant meteorological features, creating a strongly seasonal pattern of precipitation, with the majority of the annual precipitation falling between June and September. The stability the monsoons is of extreme importance for a vast range of ecosystems and for the livelihoods of a large share of the world's population. Simulations are performed with an intermediate-complexity climate model in order to assess the future response of the South Asian and East Asian monsoons to changing concentrations of aerosols and greenhouse gases. The radiative forcing associated with absorbing aerosol loading consists of a mid-tropospheric warming and a compensating surface cooling, which is applied to India, Southeast Asia, and eastern China both concurrently and independently. The primary effect of increased absorbing aerosol loading is a decrease in summer precipitation in the vicinity of the applied forcing, although the regional responses vary significantly. The decrease in precipitation is not ascribable to a decrease in the precipitable water and instead derives from a reduction in the precipitation efficiency due to changes in the stratification of the atmosphere. When the absorbing aerosol loading is added in all regions simultaneously, precipitation in eastern China is most strongly affected, with a quite distinct transition to a low precipitation regime as the radiative forcing increases beyond 60 W m−2. The response is less abrupt as we move westward, with precipitation in southern India being least affected. By applying the absorbing aerosol loading to each region individually, we are able to explain the mechanism behind the lower sensitivity observed in India and attribute it to remote absorbing aerosol forcing applied over eastern China. Additionally, we note that the effect on precipitation is approximately linear with the forcing. The impact of doubling carbon dioxide levels is to increase precipitation over the region while simultaneously weakening the circulation. When the carbon dioxide and absorbing aerosol forcings are applied at the same time, the carbon dioxide forcing partially offsets the surface cooling and reduction in precipitation associated with the absorbing aerosol response. Assessing the relative contributions of greenhouse gases and aerosols is important for future climate scenarios, as changes in the concentrations of these species has the potential to impact monsoonal precipitation.
摘要南亚和东亚夏季风是全球重要的气象特征，形成了强烈的季节性降水模式，年降水量大部分在6月至9月之间。季风的稳定性对广泛的生态系统和世界上大部分人口的生计至关重要。使用中等复杂度的气候模型进行模拟，以评估南亚和东亚季风对气溶胶和温室气体浓度变化的未来反应。与吸收气溶胶负荷相关的辐射强迫包括对流层中部变暖和补偿表面冷却，这同时和独立地应用于印度、东南亚和中国东部。吸收气溶胶负荷增加的主要影响是施加强迫附近的夏季降水量减少，尽管区域反应差异很大。降水量的减少不是由于可降水量的降低，而是由于大气分层的变化导致的降水效率的降低。当吸收气溶胶负荷在所有地区同时增加时，中国东部的降水受到的影响最为强烈，随着辐射强迫增加到60以上，向低降水状态的转变非常明显 W m−2。随着我们向西移动，反应不那么突然，印度南部的降水受到的影响最小。通过将吸收气溶胶负荷单独应用于每个地区，我们能够解释在印度观察到的较低灵敏度背后的机制，并将其归因于中国东部地区的远程吸收气溶胶强迫。此外，我们注意到，对降水的影响与强迫近似线性。二氧化碳水平翻倍的影响是增加该地区的降水量，同时削弱环流。当同时施加二氧化碳和吸收气溶胶作用力时，二氧化碳作用力部分抵消了与吸收气溶胶反应相关的地表冷却和降水减少。评估温室气体和气溶胶的相对贡献对未来的气候情景很重要，因为这些物种浓度的变化有可能影响季风降水。
{"title":"Modelling the effect of aerosol and greenhouse gas forcing on the South Asian and East Asian monsoons with an intermediate-complexity climate model","authors":"Lucy G. Recchia, V. Lucarini","doi":"10.5194/esd-14-697-2023","DOIUrl":"https://doi.org/10.5194/esd-14-697-2023","url":null,"abstract":"Abstract. The South Asian and East Asian summer monsoons are globally significant meteorological features, creating a strongly seasonal pattern of precipitation, with the majority of the annual precipitation falling between June and September. The stability the monsoons is of extreme importance for a vast range of ecosystems and for the livelihoods of a large share of the world's population. Simulations are performed with an intermediate-complexity climate model in order to assess the future response of the South Asian and East Asian monsoons to changing concentrations of aerosols and greenhouse gases. The radiative forcing associated with absorbing aerosol loading consists of a mid-tropospheric warming and a compensating surface cooling, which is applied to India, Southeast Asia, and eastern China both concurrently and independently. The primary effect of increased absorbing aerosol loading is a decrease in summer precipitation in the vicinity of the applied forcing, although the regional responses vary significantly. The decrease in precipitation is not ascribable to a decrease in the precipitable water and instead derives from a reduction in the precipitation efficiency due to changes in the stratification of the atmosphere. When the absorbing aerosol loading is added in all regions simultaneously, precipitation in eastern China is most strongly affected, with a quite distinct transition to a low precipitation regime as the radiative forcing increases beyond 60 W m−2. The response is less abrupt as we move westward, with precipitation in southern India being least affected. By applying the absorbing aerosol loading to each region individually, we are able to explain the mechanism behind the lower sensitivity observed in India and attribute it to remote absorbing aerosol forcing applied over eastern China. Additionally, we note that the effect on precipitation is approximately linear with the forcing. The impact of doubling carbon dioxide levels is to increase precipitation over the region while simultaneously weakening the circulation. When the carbon dioxide and absorbing aerosol forcings are applied at the same time, the carbon dioxide forcing partially offsets the surface cooling and reduction in precipitation associated with the absorbing aerosol response. Assessing the relative contributions of greenhouse gases and aerosols is important for future climate scenarios, as changes in the concentrations of these species has the potential to impact monsoonal precipitation.\u0000","PeriodicalId":92775,"journal":{"name":"Earth system dynamics : ESD","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48636479","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}
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