An ice-core record of vegetation and climate changes in the central Tibetan Plateau during the last 550 years

Abstract

We present a 550-year ice-core pollen record with a 5-year resolution from the Puruogangri ice field in the central Tibetan Plateau. Analysis of the relationship between pollen record and instrumental observations suggests that the sum of the steppe and meadow pollen taxa is a good indicator of summer (June-August) temperature, whereas the ratios of Cyperaceae/(Gramineae+Artemisia) [Cy/(G+A)] as well as M/S (meadow to steppe percentages) are indicative of humidity changes in this region. Together with delta (18)O and glacial accumulation records, the response of vegetation to climate change over the past 500 years was revealed. Desert vegetation dominated during 1450-1640 AD, a time period characterized by cold-wet climate, while steppe vegetation expanded during 1640-1915 when warm-dry climate prevailed. Afterwards, during a cold and humid period, desert vegetation expanded again. Since 1980-2002, due to the increase of summer temperatures, steppe and meadow vegetation predominates, while areas with desert vegetation are reduced. This proxy series is the first high-resolution ice-core pollen record spanning the last 550 years for the central Tibetan Plateau.