Spectral analysis has often been adopted in the research field of climatic changes.Many authors defined significant periods from the spectra, by which they might fore-cast future climates. Unfortunately, important dif...Spectral analysis has often been adopted in the research field of climatic changes.Many authors defined significant periods from the spectra, by which they might fore-cast future climates. Unfortunately, important differences among the results havelong been neglected because the previous authors always stressed only the similaritiesbetween their results and the others. No serious discussion was made fromthe viewpoint of periodic climatic changes. The difficulty in getting deep insight展开更多
In order to study vegetation evolution and en- vironmental change since the Last Glacial Maximum (LGM), a total of 180 pollen samples with an average time resolution of 150 years were analyzed on the top parts(0–31 m...In order to study vegetation evolution and en- vironmental change since the Last Glacial Maximum (LGM), a total of 180 pollen samples with an average time resolution of 150 years were analyzed on the top parts(0–31 m, 0–27 kaBP)of deep sea sediments from ODP Site 1144 (20°3.18′N, 1170°25.14′E), northeastern SCS. The character- istic fea- tures of pollen diagram include that pine dominates in the interglacial, and herb pollen dominates with a good deal of tropical-subtropical pollen in the last glacial, and from 18 kaBP the tropical-subtropical pollen influx rose abruptly, while the herbaceous pollen influx and percentage dropped quickly, indicating that climate turned warmer and more humid, and more tropical-subtropical vegetation grew on the mainland and the emerging continental shelf, while the grassland on the shelf diminished. A detailed comparison shows an earlier change of pollen assemblages at the glacial- interglacial transition between MIS6 and 5 (Termination II) than the ice volume change indicated by the oxygen isotope record, implying that mid-low latitude climate warming pre- ceded ice sheet retreat. Millennial-scale climatic fluctuations of vegetation change in pollen record are also discussed.展开更多
Over 40 a observed temperature data in 172 stations in China and historical proxy data were analyzed. Evidence suggested that during 1980-1994, the warmest year appeared first in southeastern part of the Qinghai_Xizan...Over 40 a observed temperature data in 172 stations in China and historical proxy data were analyzed. Evidence suggested that during 1980-1994, the warmest year appeared first in southeastern part of the Qinghai_Xizang (Tibet) Plateau (henceforth SETP) and then gradually spread northwards and eastwards to eastern China. The climatic change on century time scale in recent 600 a shows 3 relatively warm and clod stages in China. Each warm and cold stage appeared first in Tibet Plateau (henceforth TP) and then in the Qilian Mountains, then in the eastern parts of China. The warm and cold stages in TP were 10-60 a earlier than in the eastern China. The facts show that TP is a pilot region of climatic fluctuation in China on the time scale shorter than 10\+3a.展开更多
文摘Spectral analysis has often been adopted in the research field of climatic changes.Many authors defined significant periods from the spectra, by which they might fore-cast future climates. Unfortunately, important differences among the results havelong been neglected because the previous authors always stressed only the similaritiesbetween their results and the others. No serious discussion was made fromthe viewpoint of periodic climatic changes. The difficulty in getting deep insight
基金supported by the State Key Basic Research and Development Plan of China(Grant No.G2000078502)the National Natural Science Foundation of China(Grant Nos.49999560 and 49901018).
文摘In order to study vegetation evolution and en- vironmental change since the Last Glacial Maximum (LGM), a total of 180 pollen samples with an average time resolution of 150 years were analyzed on the top parts(0–31 m, 0–27 kaBP)of deep sea sediments from ODP Site 1144 (20°3.18′N, 1170°25.14′E), northeastern SCS. The character- istic fea- tures of pollen diagram include that pine dominates in the interglacial, and herb pollen dominates with a good deal of tropical-subtropical pollen in the last glacial, and from 18 kaBP the tropical-subtropical pollen influx rose abruptly, while the herbaceous pollen influx and percentage dropped quickly, indicating that climate turned warmer and more humid, and more tropical-subtropical vegetation grew on the mainland and the emerging continental shelf, while the grassland on the shelf diminished. A detailed comparison shows an earlier change of pollen assemblages at the glacial- interglacial transition between MIS6 and 5 (Termination II) than the ice volume change indicated by the oxygen isotope record, implying that mid-low latitude climate warming pre- ceded ice sheet retreat. Millennial-scale climatic fluctuations of vegetation change in pollen record are also discussed.
文摘Over 40 a observed temperature data in 172 stations in China and historical proxy data were analyzed. Evidence suggested that during 1980-1994, the warmest year appeared first in southeastern part of the Qinghai_Xizang (Tibet) Plateau (henceforth SETP) and then gradually spread northwards and eastwards to eastern China. The climatic change on century time scale in recent 600 a shows 3 relatively warm and clod stages in China. Each warm and cold stage appeared first in Tibet Plateau (henceforth TP) and then in the Qilian Mountains, then in the eastern parts of China. The warm and cold stages in TP were 10-60 a earlier than in the eastern China. The facts show that TP is a pilot region of climatic fluctuation in China on the time scale shorter than 10\+3a.
