The question of whether or not global warming has paused since more than ten years ago, namely ＂warming hia- tus＂, has attracted the attention of climate science community including the IPCC. Some authors have attri...The question of whether or not global warming has paused since more than ten years ago, namely ＂warming hia- tus＂, has attracted the attention of climate science community including the IPCC. Some authors have attributed the ＂warming hiatus＂ to the internal changes in the climate system, i.e., the recombination of ocean-atmosphere circulations. Therefore, it is necessary to propose higher requirements on reconstructing circulation background of climate change for the past millennium. However, the analyses of changes in atmospheric circulation over the last millennium as well as the conclusions of related re- gional climate patterns are so widely different and contradictory, bringing uncertainties to our understanding of regional even global climate change to a great extent. On the other hand, in the last 10 years the high-precision U/Th-dated stalagmite oxygen isotope ratio （δ^18O） sequences provided an accurate chronological frame for the paleoclimate study of the middle and late Pleistocene, in which all authors from China took the Chinese stalagmite δ^18O as the summer monsoon index without excep- tion. However, this point of view misleads the climate scientists into thinking that the stalagmite δ^18O can be as the proxy of precipitation amount. Nevertheless, it is well known that all of these records have a lot in common in the low frequency trend. However, most sequences cannot be calibrated by instrumental precipitation records, and thus the uncertainty of the climate research framework of China and even of the world has increased. Therefore, it is imperative for climatology to clarify the origin of contradiction and to reduce the uncertainty as early as possible. On the basis of analyzing the significance of stalag- mite ~180 in the monsoon regions of China, the author tries to propose a new circulation proxy in this paper： integrating the Chinese stalagmite oxygen isotope sequence to reconstruct the tropical Pacific sea surface temperature gradient, i.e., the large-scale ENSO-like state over the past millennium. Furthermore, the author speculates that it was warm in the modern times and the Medieval Period, but the circulation recombination was different in both periods. And this inference could be support- ed by the longer record since Last Glacial Maximum. In other words, the attribution analysis of the identical low-frequency trends of Chinese stalagmite t^180 on a large scale shows that the ENSO-like state controls the climate change in the monsoon regions of China at different time scales （from interannual to century or even longer time scales）. Wherein the important connection of circulations is the western Pacific subtropical high （WPSH）, that is to say, besides the interannual and decadal time scales, the WPSH would possess the circulation mode on longer timescales. For example, we may discuss the change of the WPSH in the whole Holocene epoch, i.e., the half precession period. These discussions could make sense to the study of not only the paleoclimate but also the modern climate.展开更多
基金supported by the Chinese Academy of Sciences Strategic Priority Research Program (Grant No. XDA05080501)the National Basic Research Program of China (Grant No. 2010CB950101)+1 种基金the National Natural Science Foundation of China (Grant No. 41030103)Basic Research Project of the Ministry of Science and Technology (Grant No. 2011FY120300)
文摘The question of whether or not global warming has paused since more than ten years ago, namely ＂warming hia- tus＂, has attracted the attention of climate science community including the IPCC. Some authors have attributed the ＂warming hiatus＂ to the internal changes in the climate system, i.e., the recombination of ocean-atmosphere circulations. Therefore, it is necessary to propose higher requirements on reconstructing circulation background of climate change for the past millennium. However, the analyses of changes in atmospheric circulation over the last millennium as well as the conclusions of related re- gional climate patterns are so widely different and contradictory, bringing uncertainties to our understanding of regional even global climate change to a great extent. On the other hand, in the last 10 years the high-precision U/Th-dated stalagmite oxygen isotope ratio （δ^18O） sequences provided an accurate chronological frame for the paleoclimate study of the middle and late Pleistocene, in which all authors from China took the Chinese stalagmite δ^18O as the summer monsoon index without excep- tion. However, this point of view misleads the climate scientists into thinking that the stalagmite δ^18O can be as the proxy of precipitation amount. Nevertheless, it is well known that all of these records have a lot in common in the low frequency trend. However, most sequences cannot be calibrated by instrumental precipitation records, and thus the uncertainty of the climate research framework of China and even of the world has increased. Therefore, it is imperative for climatology to clarify the origin of contradiction and to reduce the uncertainty as early as possible. On the basis of analyzing the significance of stalag- mite ~180 in the monsoon regions of China, the author tries to propose a new circulation proxy in this paper： integrating the Chinese stalagmite oxygen isotope sequence to reconstruct the tropical Pacific sea surface temperature gradient, i.e., the large-scale ENSO-like state over the past millennium. Furthermore, the author speculates that it was warm in the modern times and the Medieval Period, but the circulation recombination was different in both periods. And this inference could be support- ed by the longer record since Last Glacial Maximum. In other words, the attribution analysis of the identical low-frequency trends of Chinese stalagmite t^180 on a large scale shows that the ENSO-like state controls the climate change in the monsoon regions of China at different time scales （from interannual to century or even longer time scales）. Wherein the important connection of circulations is the western Pacific subtropical high （WPSH）, that is to say, besides the interannual and decadal time scales, the WPSH would possess the circulation mode on longer timescales. For example, we may discuss the change of the WPSH in the whole Holocene epoch, i.e., the half precession period. These discussions could make sense to the study of not only the paleoclimate but also the modern climate.
