The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the ...The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate.Paleo, observational and modelling studies are covered to summarize several major themes, including： the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response（e.g., atmospheric circulation, air temperature） to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.展开更多
This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the inter...This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the international community. In historical climate simulations, changes in solar radiation and volcanic activity explain most parts of reconstructions over the last millennium prior to the industrial era, while atmospheric greenhouse gas concentrations play the most important role in the20 th century warming over China. There is a considerable model–data mismatch in the annual and boreal winter temperature change over China during the mid-Holocene [6000 years before present（ka BP）], while coupled models with an interactive ocean generally perform better than atmospheric models. For the Last Glacial Maximum（21 ka BP）, climate models successfully reproduce the surface cooling trend over China but fail to reproduce its magnitude, with a better performance for coupled models. At that time, reconstructed vegetation and western Pacific sea surface temperatures could have significantly affected the East Asian climate, and environmental conditions on the Qinghai–Tibetan Plateau were most likely very different to the present day. During the late Marine Isotope Stage 3（30–40 ka BP）, orbital forcing and Northern Hemisphere glaciation, as well as vegetation change in China, were likely responsible for East Asian climate change. On the tectonic scale,the Qinghai–Tibetan Plateau uplift, the Tethys Sea retreat, and the South China Sea expansion played important roles in the formation of the East Asian monsoon-dominant environment pattern during the late Cenozoic.展开更多
Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large u...Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.展开更多
The mid-Pliocene warm period was the most recent geological period in Earth＇s history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds （EASWs） streng...The mid-Pliocene warm period was the most recent geological period in Earth＇s history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds （EASWs） strengthened in monsoonal China, and that East Asian winter winds （EAWWs） weakened in northern monsoonal China during this period, as compared to the pre-industrial period. However, the corresponding mechanisms are still unclear. In this paper, the results of a set of numerical simulations are reported to analyze the effects of changed boundary conditions on the mid-Pliocene East Asian monsoon climate, based on PRISM3 （Pliocene Research Interpretation and Synoptic Mapping） palaeoenvironmental recon- struction. The model results showed that the combined changes of sea surface temperatures, atmospheric CO2 concentration, and ice sheet extent were necessary to generate an overall warm climate on a large scale, and that these factors exerted the greatest effects on the strengthening of EASWs in monsoonal China. The orographic change produced significant local warming and had the greatest effect on the weakening of EAWWs in northern monsoonal China in the mid-Pliocene. Thus, these two factors both had important but different effects on the monsoon change. In comparison, the effects of vegetational change on the strengthened EASWs and weakened EAWWs were relatively weak. The changed monsoon winds can be ex- plained by a reorganization of the meridional temperature gradient and zonal thermal contrast. Moreover, the effect of orbital parameters cannot be ignored. Results showed that changes in orbital parameters could have marked!y affected the EASWs and EAWWs, and caused significant short-term oscillations in the mid-Pliocene monsoon climate in East Asia.展开更多
The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolia...The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolian sediments. In this study, we analyzed the behavior and the possible mechanism involved in the change of the westerlies, mainly in terms of the jet stream position, in the mid-Pliocene warm period （3.3 to 3.0 million years ago） using simulations of 15 climate models from the Pliocene Model Intercomparison Project （PlioMIP）. Compared to the reference period, the mid-Pliocene midlatitude westerlies generally shifted poleward （approximately 3.6° of latitude in the Northern Hemisphere and 1.9~ of latitude in the Southern Hemisphere at 850 hPa level） with a dipole pattern. The dipole pattern of the tropospheric zonal wind anomalies was closely related to the change of the tropospheric meridional temperature gradient as a result of thermal structure adjustment. The poleward shift of the midlatitude westerly jet corresponded to the poleward shift of the mean meridional circulation. The sea surface temperatures and sea ice may have affected the simulated temperature structure and zonal winds, causing the spread of the westerly anomalies in the mid-Pliocene between the atmosphere-only and coupled atmosphere-ocean general circulation model simulations.展开更多
Tropical cyclones(TCs)not only passively respond to climate change,but also play an important role in vertical mixing of the upper ocean and in driving oceanic heat transport.Using a fully coupled climate model,the au...Tropical cyclones(TCs)not only passively respond to climate change,but also play an important role in vertical mixing of the upper ocean and in driving oceanic heat transport.Using a fully coupled climate model,the authors investigate the potential effect of TC-induced vertical mixing on the El Nino–Southern Oscillation(ENSO)and East Asian monsoon in the mid-Piacenzian,during which global TCs are estimated to have been stronger.Sensitivity experiments indicate that the TC-induced oceanic mixing over global storm basins leads to additional warming over the eastern tropical Pacific and a deeper thermocline in the mid-Piacenzian,whereas it dampens the interannual variability of ENSO.Regarding the East Asian monsoon circulations,low-level(850 hPa)summer and winter winds are intensified in response to enhanced vertical mixing,with a southward/westward shift of the western North Pacific high and westerly jet in summer and a deepened East Asian trough in winter.These climatic features are largely reproduced in the experiment with enhanced vertical mixing only over the central-eastern North Pacific.These results may shed light on TC feedbacks associated with vertical mixing and advance our understanding on mid-Piacenzian climate.展开更多
The Middle Pliocene (ca 3.12–2.97 Ma) is a recent warm period in the Earth’s history. In many respects, the warmth of the Middle Pliocene is similar to the probable warm situation of the late 21st century predicted ...The Middle Pliocene (ca 3.12–2.97 Ma) is a recent warm period in the Earth’s history. In many respects, the warmth of the Middle Pliocene is similar to the probable warm situation of the late 21st century predicted by climate models. Understanding the Middle Pliocene climate is important in predicting the future climate with global warming. Here, we used the latest reconstructions for the Middle Pliocene—Pliocene Research Interpretation and Synoptic Mapping (PRISM) version 3—to simulate the Middle Pliocene climate with a fully coupled model Fast Ocean Atmosphere Model. From comparison of the results of simulations with reconstructions, we considered two important scientific topics of Middle Pliocene climate modeling: extreme warming in the subpolar North Atlantic and a permanent El Ni?o in the tropical Pacific. Our simulations illustrate that the global annual mean sea surface temperature (SST) in the Middle Pliocene was about 2.3°C higher than that in the pre-industrial era. The warming was stronger at midand high latitudes than at low latitudes. The simulated SST changes agree with SST reconstructions in PRISM3 data, especially for the North Atlantic, North Pacific and west coast of South America. However, there were still discrepancies between the simulation of the SST and reconstructions for the subpolar North Atlantic and tropical Pacific. In the case of the Atlantic, the weakened meridional overturning circulation in the simulation did not support the reconstruction of the extremely warm condition in the subpolar North Atlantic. In the case of the tropical Pacific, the whole ocean warmed, especially the eastern tropical Pacific, which did not support the permanent El Ni?o suggested by the reconstruction. From evaluation of the modeling and reconstruction, we suggest that the above discrepancies were due to uncertainties in reconstructions, difficulties in paleoclimate modeling and deficiencies of climate models. The discrepancies should be reduced through consideration of both the modeling and data.展开更多
基金supported by the Research Council of Norway through the Blue Arc project (207650/ E10)the European Union 7th Framework Programme (FP7 20072013) through the NACLIM project (308299)+1 种基金the National Natural Sciences Foundation of China through projects 41375083 and 41210007the Nord Forsk-funded project GREENICE (61841): Impacts of Sea-Ice and Snow-Cover Changes on Climate, Green Growth, and Society
文摘The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate.Paleo, observational and modelling studies are covered to summarize several major themes, including： the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response（e.g., atmospheric circulation, air temperature） to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB03020602)supported by the Key Directional Program of the Knowledge-innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2–YW–338– 2)+2 种基金supported by the National Basic Research Program of China (Grant No. 2007CB815901)supported by the National Basic Research Program of China (Grant No. 2010CB950102)supported by the National Natural Science Foundation of China (Grant No. 40875043)
文摘This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the international community. In historical climate simulations, changes in solar radiation and volcanic activity explain most parts of reconstructions over the last millennium prior to the industrial era, while atmospheric greenhouse gas concentrations play the most important role in the20 th century warming over China. There is a considerable model–data mismatch in the annual and boreal winter temperature change over China during the mid-Holocene [6000 years before present（ka BP）], while coupled models with an interactive ocean generally perform better than atmospheric models. For the Last Glacial Maximum（21 ka BP）, climate models successfully reproduce the surface cooling trend over China but fail to reproduce its magnitude, with a better performance for coupled models. At that time, reconstructed vegetation and western Pacific sea surface temperatures could have significantly affected the East Asian climate, and environmental conditions on the Qinghai–Tibetan Plateau were most likely very different to the present day. During the late Marine Isotope Stage 3（30–40 ka BP）, orbital forcing and Northern Hemisphere glaciation, as well as vegetation change in China, were likely responsible for East Asian climate change. On the tectonic scale,the Qinghai–Tibetan Plateau uplift, the Tethys Sea retreat, and the South China Sea expansion played important roles in the formation of the East Asian monsoon-dominant environment pattern during the late Cenozoic.
基金funded by the National Basic Research Program of China(Grant Nos.2010CB950102 and 2009CB421406)the Nansen Scientific Society(Norway)part of the SeaLev projects at the Centre of Climate Dynamics/Bjerknes Center in Bergen
文摘Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.
基金supported by the Strategic Priority Research Program (Grant No. XDB03020602) of the Chinese Academy of Sciencesby the National Natural Science Foundation of China (Grant Nos. 41175072 and 41305073)
文摘The mid-Pliocene warm period was the most recent geological period in Earth＇s history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds （EASWs） strengthened in monsoonal China, and that East Asian winter winds （EAWWs） weakened in northern monsoonal China during this period, as compared to the pre-industrial period. However, the corresponding mechanisms are still unclear. In this paper, the results of a set of numerical simulations are reported to analyze the effects of changed boundary conditions on the mid-Pliocene East Asian monsoon climate, based on PRISM3 （Pliocene Research Interpretation and Synoptic Mapping） palaeoenvironmental recon- struction. The model results showed that the combined changes of sea surface temperatures, atmospheric CO2 concentration, and ice sheet extent were necessary to generate an overall warm climate on a large scale, and that these factors exerted the greatest effects on the strengthening of EASWs in monsoonal China. The orographic change produced significant local warming and had the greatest effect on the weakening of EAWWs in northern monsoonal China in the mid-Pliocene. Thus, these two factors both had important but different effects on the monsoon change. In comparison, the effects of vegetational change on the strengthened EASWs and weakened EAWWs were relatively weak. The changed monsoon winds can be ex- plained by a reorganization of the meridional temperature gradient and zonal thermal contrast. Moreover, the effect of orbital parameters cannot be ignored. Results showed that changes in orbital parameters could have marked!y affected the EASWs and EAWWs, and caused significant short-term oscillations in the mid-Pliocene monsoon climate in East Asia.
基金the Pliocene Model Intercomparison Project (Plio MIP) modeling groups (listed in Table 1 of this paper) for producing and making available their model outputsupported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB03020602)the National Natural Science Foundation of China (Grant Nos. 41430962 and 41421004)
文摘The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolian sediments. In this study, we analyzed the behavior and the possible mechanism involved in the change of the westerlies, mainly in terms of the jet stream position, in the mid-Pliocene warm period （3.3 to 3.0 million years ago） using simulations of 15 climate models from the Pliocene Model Intercomparison Project （PlioMIP）. Compared to the reference period, the mid-Pliocene midlatitude westerlies generally shifted poleward （approximately 3.6° of latitude in the Northern Hemisphere and 1.9~ of latitude in the Southern Hemisphere at 850 hPa level） with a dipole pattern. The dipole pattern of the tropospheric zonal wind anomalies was closely related to the change of the tropospheric meridional temperature gradient as a result of thermal structure adjustment. The poleward shift of the midlatitude westerly jet corresponded to the poleward shift of the mean meridional circulation. The sea surface temperatures and sea ice may have affected the simulated temperature structure and zonal winds, causing the spread of the westerly anomalies in the mid-Pliocene between the atmosphere-only and coupled atmosphere-ocean general circulation model simulations.
基金funded by the National Natural Science Foundation of China [grant number 41772179]the Young Elite Scientists Sponsorship Program by China Association for Science and Technology [grant number 2017QNRC001]
文摘Tropical cyclones(TCs)not only passively respond to climate change,but also play an important role in vertical mixing of the upper ocean and in driving oceanic heat transport.Using a fully coupled climate model,the authors investigate the potential effect of TC-induced vertical mixing on the El Nino–Southern Oscillation(ENSO)and East Asian monsoon in the mid-Piacenzian,during which global TCs are estimated to have been stronger.Sensitivity experiments indicate that the TC-induced oceanic mixing over global storm basins leads to additional warming over the eastern tropical Pacific and a deeper thermocline in the mid-Piacenzian,whereas it dampens the interannual variability of ENSO.Regarding the East Asian monsoon circulations,low-level(850 hPa)summer and winter winds are intensified in response to enhanced vertical mixing,with a southward/westward shift of the western North Pacific high and westerly jet in summer and a deepened East Asian trough in winter.These climatic features are largely reproduced in the experiment with enhanced vertical mixing only over the central-eastern North Pacific.These results may shed light on TC feedbacks associated with vertical mixing and advance our understanding on mid-Piacenzian climate.
基金supported by the National Basic Research Program of China(2009CB421406)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q1-02)the National Natural Science Foundation of China (4090205 and 40975050)
文摘The Middle Pliocene (ca 3.12–2.97 Ma) is a recent warm period in the Earth’s history. In many respects, the warmth of the Middle Pliocene is similar to the probable warm situation of the late 21st century predicted by climate models. Understanding the Middle Pliocene climate is important in predicting the future climate with global warming. Here, we used the latest reconstructions for the Middle Pliocene—Pliocene Research Interpretation and Synoptic Mapping (PRISM) version 3—to simulate the Middle Pliocene climate with a fully coupled model Fast Ocean Atmosphere Model. From comparison of the results of simulations with reconstructions, we considered two important scientific topics of Middle Pliocene climate modeling: extreme warming in the subpolar North Atlantic and a permanent El Ni?o in the tropical Pacific. Our simulations illustrate that the global annual mean sea surface temperature (SST) in the Middle Pliocene was about 2.3°C higher than that in the pre-industrial era. The warming was stronger at midand high latitudes than at low latitudes. The simulated SST changes agree with SST reconstructions in PRISM3 data, especially for the North Atlantic, North Pacific and west coast of South America. However, there were still discrepancies between the simulation of the SST and reconstructions for the subpolar North Atlantic and tropical Pacific. In the case of the Atlantic, the weakened meridional overturning circulation in the simulation did not support the reconstruction of the extremely warm condition in the subpolar North Atlantic. In the case of the tropical Pacific, the whole ocean warmed, especially the eastern tropical Pacific, which did not support the permanent El Ni?o suggested by the reconstruction. From evaluation of the modeling and reconstruction, we suggest that the above discrepancies were due to uncertainties in reconstructions, difficulties in paleoclimate modeling and deficiencies of climate models. The discrepancies should be reduced through consideration of both the modeling and data.
