Recent temperature increase recorded in an ice core in the source region of Yangtze River

Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ^(18)O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ^(18)O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the begin-ning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warm-ing and a more sensitive response to global warming in the high elevation region.

Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau （TP）. A 70-year history of preclpltstlon δ^18O has been recovered using an ice core record retrieved In a plat portion of the flrn area In the Guoqu Glacier （33°34＇37.8＂N, 91°10＇35.3＂E, 5720 m a.s.l.）, Mt. Geladaindong （the source region of Yangtze River）, in November, 2005. By using a significant positive relationship between ice core 8180 record and summer air temperature （July to September） from the nearby meteorological ststlons, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred In the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the beginning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 197011 Is much higher that that in the central TP and the Northern Hemisphere （Nil）, and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the Nil, reflecting an accelerated warming and a more sensitive response to global warming in the high elevation region.