Glaciers in China can be categorized into 3 types, i.e. the maritime (temperate) type, sub-continental (sub-polar) type and extreme Continental (polar) type, which take 22%, 46% and 32% of the total existing glacier a...Glaciers in China can be categorized into 3 types, i.e. the maritime (temperate) type, sub-continental (sub-polar) type and extreme Continental (polar) type, which take 22%, 46% and 32% of the total existing glacier area (59 406 km2) respectively. Researches indicate that glaciers of the three types show different response patterns to the global warming. Since the Maxima of the Little Ice Age (the 17th century), air temperature has risen at a magnitude of 1.3℃on average and the glacier area decreased corresponds to 20% of the present total glacier area in western China. it is estimated that air temperature rise in the 2030s, 2070s and 2100s will be of the order of 0.4-1.2, 1.2-2.7 and 2.1-4.0 K in western China. With these scenarios, glaciers in China will suffer from further shrinkage by 12%, 28% and 45% by the 2030s, 2070s and 2100s. The uncertainties may account for 30%-67% in 2100 in China.展开更多
Using meteorological observations, proxies of precipitation and temperature, and climate simulation outputs, we synthetically analyzed the regularities of decadal-centennial-scale changes in the summer thermal contras...Using meteorological observations, proxies of precipitation and temperature, and climate simulation outputs, we synthetically analyzed the regularities of decadal-centennial-scale changes in the summer thermal contrast between land and ocean and summer precipitation over the East Asian monsoon region during the past millennium; compared the basic characteristics of the East Asian summer monsoon (EASM) circulation and precipitation in the present day, the Little Ice Age (LIA) and the Medieval Warm Period (MWP); and explored their links with solar irradiance and global climate change. The results indicate that over the last 150 years, the EASM circulation and precipitation, indicated by the temperature contrast between the East Asian mainland and adjacent oceans, had a significant decadal perturbation and have been weaker during the period of rapid global warming over the past 50 years. On the centennial time scale, the EASM in the MWP was strongest over the past 1000 years. Over the past 1000 years, the EASM was weakest in 1450-1570. When the EASM circulation was weaker, the monsoon rain belt over eastern China was generally located more southward, with there being less precipitation in North China and more precipitation in the Yangtze River valley; therefore, there was an anomalous pattern of southern flood/northern drought. From the 1900s to 1920s, precipitation had a pat- tern opposite to that of the southern flood/northern drought, with there being less precipitation in the Yangtze River valley and more precipitation in North China. Compared with the case for the MWP, there was a longer-time-scale southern flood/northern drought phenomenon in 1400-1600. Moreover, the EASM circulation and precipitation did not synchronously vary with the trend of global temperature. During the last 150 years, although the annual mean surface temperature around the world and in China has increased, the EASM circulation and precipitation did not have strengthening or weakening trends. Over the past 1000 years, the weakest EASM oc展开更多
To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system mode...To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-latitudes of the North Pacific. However, the magnitude of the warming is weaker than that in the 20th century. The warming in the high latitudes of the Northern Hemisphere is stronger than that in the Southern Hemisphere. The LIA cooling is also evident on a global scale, with a strong cooling over the high Eurasian continent, while the cooling center is over the Arctic domain. Both the MWP and the 20CW experiments exhibit the strongest warming anomalies in the middle troposphere around 200-300 hPa, but the cooling center of the LIA experiment is seen in the polar surface of the Northern Hemisphere. A comparison of model simulation against the reconstruction indicates that model's performance in simulating the surface air temperature changes during the warm periods is better than that during the cold periods. The consistencies between model and reconstruction in lower latitudes are better than those in high latitudes. Comparison of the inter-annual variability mode of East Asian summer monsoon (EASM) rainfall during the MWP, LIA and 20CW reveals a similar rainfall anomalies pattern. However, the time spectra of the principal component during the three typical periods of the last millennium are different, and the quasi-biannual oscillation is more evident during the two warm periods. At a centennial time scale, the external mode of the EASM variability driven by the changes of effective solar radiation is determined by the changes of large scale land-sea thermal contrast. The rainfall anomalies over the east of 1展开更多
Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to i...Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to indicate the variations of East Asia Winter Monsoon (EAWM), with high (low) content/mean-size of ESGCS denote to strong (weak) EAWM. Combined with AMS14C datings core B2 provides a continuous high-resolution record of EAWM changes over the past 2300 years, with an average resolution of 13 years. The results show that the variations of EAWM are con-sistent with temperature changes inferred from historical documents in eastern China over the past 2300 years, from which four climate stages may be identified. In stages before 1900 aBP (50 AD) and 1450―780 aBP (50―1170 AD) the EAWM were comparatively weak, corresponding to warm climate periods in eastern China, respectively. And in stages of 1900―1450 aBP (50―500 AD) and 780―219 aBP (1170―1731 AD) the EAWM were strongly developed, which correspond well to climate changes of two cold periods in eastern China. It is also shown from this study that the stage at 780―219 aBP (1170―1731 AD) was the coldest climate period during the last 2300 years and could be, therefore, related to the Little Ice Age (LIA). Climatic fluctuations appeared obviously in all the four stages, and two climate events of abrupt changes from warm to cold occurred at around 1900 aBP (50 AD) and 780 aBP (1170 AD), of which the latter is probably related to globe-scale changes of atmospheric circulation at that time.展开更多
文摘Glaciers in China can be categorized into 3 types, i.e. the maritime (temperate) type, sub-continental (sub-polar) type and extreme Continental (polar) type, which take 22%, 46% and 32% of the total existing glacier area (59 406 km2) respectively. Researches indicate that glaciers of the three types show different response patterns to the global warming. Since the Maxima of the Little Ice Age (the 17th century), air temperature has risen at a magnitude of 1.3℃on average and the glacier area decreased corresponds to 20% of the present total glacier area in western China. it is estimated that air temperature rise in the 2030s, 2070s and 2100s will be of the order of 0.4-1.2, 1.2-2.7 and 2.1-4.0 K in western China. With these scenarios, glaciers in China will suffer from further shrinkage by 12%, 28% and 45% by the 2030s, 2070s and 2100s. The uncertainties may account for 30%-67% in 2100 in China.
基金the National Natural Science Foundation of China (40890053 and 40890052)the National Basic Research Program of China (2007CB815901)the Special Project of Basic Science and Technology (2011FY120300)
文摘Using meteorological observations, proxies of precipitation and temperature, and climate simulation outputs, we synthetically analyzed the regularities of decadal-centennial-scale changes in the summer thermal contrast between land and ocean and summer precipitation over the East Asian monsoon region during the past millennium; compared the basic characteristics of the East Asian summer monsoon (EASM) circulation and precipitation in the present day, the Little Ice Age (LIA) and the Medieval Warm Period (MWP); and explored their links with solar irradiance and global climate change. The results indicate that over the last 150 years, the EASM circulation and precipitation, indicated by the temperature contrast between the East Asian mainland and adjacent oceans, had a significant decadal perturbation and have been weaker during the period of rapid global warming over the past 50 years. On the centennial time scale, the EASM in the MWP was strongest over the past 1000 years. Over the past 1000 years, the EASM was weakest in 1450-1570. When the EASM circulation was weaker, the monsoon rain belt over eastern China was generally located more southward, with there being less precipitation in North China and more precipitation in the Yangtze River valley; therefore, there was an anomalous pattern of southern flood/northern drought. From the 1900s to 1920s, precipitation had a pat- tern opposite to that of the southern flood/northern drought, with there being less precipitation in the Yangtze River valley and more precipitation in North China. Compared with the case for the MWP, there was a longer-time-scale southern flood/northern drought phenomenon in 1400-1600. Moreover, the EASM circulation and precipitation did not synchronously vary with the trend of global temperature. During the last 150 years, although the annual mean surface temperature around the world and in China has increased, the EASM circulation and precipitation did not have strengthening or weakening trends. Over the past 1000 years, the weakest EASM oc
基金the National Natural Science Foundation of China (40890054)
文摘To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-latitudes of the North Pacific. However, the magnitude of the warming is weaker than that in the 20th century. The warming in the high latitudes of the Northern Hemisphere is stronger than that in the Southern Hemisphere. The LIA cooling is also evident on a global scale, with a strong cooling over the high Eurasian continent, while the cooling center is over the Arctic domain. Both the MWP and the 20CW experiments exhibit the strongest warming anomalies in the middle troposphere around 200-300 hPa, but the cooling center of the LIA experiment is seen in the polar surface of the Northern Hemisphere. A comparison of model simulation against the reconstruction indicates that model's performance in simulating the surface air temperature changes during the warm periods is better than that during the cold periods. The consistencies between model and reconstruction in lower latitudes are better than those in high latitudes. Comparison of the inter-annual variability mode of East Asian summer monsoon (EASM) rainfall during the MWP, LIA and 20CW reveals a similar rainfall anomalies pattern. However, the time spectra of the principal component during the three typical periods of the last millennium are different, and the quasi-biannual oscillation is more evident during the two warm periods. At a centennial time scale, the external mode of the EASM variability driven by the changes of effective solar radiation is determined by the changes of large scale land-sea thermal contrast. The rainfall anomalies over the east of 1
基金supported by the National Natural Science Foundation of China(Grant Nos.90211022 and 40206007)the Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX3-SW-220).
文摘Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to indicate the variations of East Asia Winter Monsoon (EAWM), with high (low) content/mean-size of ESGCS denote to strong (weak) EAWM. Combined with AMS14C datings core B2 provides a continuous high-resolution record of EAWM changes over the past 2300 years, with an average resolution of 13 years. The results show that the variations of EAWM are con-sistent with temperature changes inferred from historical documents in eastern China over the past 2300 years, from which four climate stages may be identified. In stages before 1900 aBP (50 AD) and 1450―780 aBP (50―1170 AD) the EAWM were comparatively weak, corresponding to warm climate periods in eastern China, respectively. And in stages of 1900―1450 aBP (50―500 AD) and 780―219 aBP (1170―1731 AD) the EAWM were strongly developed, which correspond well to climate changes of two cold periods in eastern China. It is also shown from this study that the stage at 780―219 aBP (1170―1731 AD) was the coldest climate period during the last 2300 years and could be, therefore, related to the Little Ice Age (LIA). Climatic fluctuations appeared obviously in all the four stages, and two climate events of abrupt changes from warm to cold occurred at around 1900 aBP (50 AD) and 780 aBP (1170 AD), of which the latter is probably related to globe-scale changes of atmospheric circulation at that time.
