Summer temperature reconstruction on the central Tibetan Plateau during 1860–2002 derived from annually resolved ice core pollen

Abstract

We present a 140‐year ice core pollen record with annual time resolution from the Puruogangri ice field in the central Tibetan Plateau. A linear regression model between the sum of the steppe and meadow pollen taxa and summer temperature at Naqu accounts for 66% of the summer temperature variance for the period 1955–2002. On the basis of this model, we reconstructed summer temperature history for the central Tibetan Plateau from 1860 to 2002. Three marked warm periods during the 1870s, 1890s, and 1990s and five cold periods during the 1860s, 1880s, 1900s, 1950s, and 1960–1970s were identified. Within the last 100 years, late 20th century warming is distinctive and may have had a major role in the present retreat of most glaciers on the Tibetan Plateau. The pollen record is also significantly correlated with average annual temperatures over the whole Tibetan Plateau, suggesting that these proxy data have the potential for reflecting large‐scale regional temperature change. The statistically significant similarity between the Puruogangri ice core pollen record and the δ18O time series indicates that both are reliable indicators of temperature change at annual to multiyear timescales in this region.

Surface pressure record of Tibetan Plateau warming since the 1870s

“…The long-term estimate of the warming is consistent with both tree ring and ice core pollen data from the TP (Wu, 1995;Yang et al, 2008). The long-term warming estimated from the surface pressure tendency over the plateau is of the same order as the long-term hemispheric warming (Liu and Chen, 2000), suggesting that the recent acceleration in warming over the plateau is not a long-term phenomenon.…”

“…• C from 1860 to 2001 (Yang et al, 2008). Atmospheric reanalysis projects that make use of modern numerical weather prediction systems to assimilate historical observations into consistent and homogeneous datasets have revolutionized the diagnosis of atmospheric processes and their impact on many aspects of the climate system (Kalnay et al, 1996;Bengtsson et al, 2004;Simmons et al, 2010;Dee et al, 2011a).…”

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

“…Therefore, the density and yield of the dominant plants including Artemisia and Chenopodiaceae in the alpine frost steppe or alpine meadow vegetation in the central plateau is most likely controlled by summer temperature. Correlation analysis between the pollen record from the annually resolved upper 34.2 m of the PRGR ice core (spanning the last 150 years) and meteorological data from nearby weather stations in the central Tibetan Plateau found a significant correlation between the pollen percentages of steppe and meadow plants and June August temperatures during the 1955 2002 period [2]. The resulting150-year summer temperature reconstruction and 18 O values recorded in the same ice core were quite consistent [2], showing that both the pollen percentage of herbaceous plants from the ice core and the 18 O records are suitable proxies for summer temperature changes ( Figure 3).…”

“…In previous studies [2], we used 1114 samples from the upper 34.24 m of the ice core to reconstruct annual pollen and 18 O series over the past 140 years (1860 2000 AD) based on dust layer counting along with seasonal variations of 18 O and dust concentration [2,13]. Below this ice layer, the dust layers became thin and annual layers were difficult to identify precisely, hence a flow model was used to determine the age of the ice cores.…”

“…Pollen analysis is one of the most important paleoclimatic archives for terrestrial environments, and it has been widely used for climate reconstruction, but few studies of ice-core pollen have been carried out in China [1,2]. Earlier studies on ice-core pollen were mainly focused on polar ice cores, where pollen concentration is very low and the pollen is mostly transported from regions hundreds to thousands of kilometers away.…”