Precipitation variation in the northeastern Tibetan Plateau recorded by the tree rings since 850 AD and its relevance to the Northern Hemisphere temperature

Abstract

Three well-dated Sabina Przewalskii ring-width chronologies from Dulan, China, have been used to reconstruct annual precipitation (from prior July to current June) variations on the northeast Tibetan Plateau since 850 AD. The reconstructions account of the instrumentally recorded precipitation variance are: 54.7% for the period of 1385-2000AD; 50.5% for 1099-1384AD and 45.7% for 850-1098AD. On the millenary scale, the precipitation variation over this region displays "W" shape, which has three peaks and two valleys. The precipitation is low during 1571-1879 AD, and high during 1880-2000 AD. 1900-2000 AD is the century with the highest precipitation over the northeast Tibetan Plateau in the last 1000 years, and 1962-2000 is the period with the highest precipitation, and the highest variability of precipitation as well in the last 1000 years. The reconstructed series also reveals that the variability of annual precipitation is large when the precipitation is more, and contrarily, variability is small when the precipitation is low. With the temperature increasing obviously in the 20th century, the precipitation in the study region significantly increased too, the variability of precipitation became larger, and drought and flooding occurred more frequently.The yearly tree-ring width (high frequency signal) series in this region reflects the local annually precipitation variation. However, the series with 40-year moving average (low frequency signal) corresponds to the Northern Hemisphere temperature variations on the decadal to centurial scale. It correlates significantly with seven temperature curves of the Northern Hemisphere in the different time spans. For example, the correlation coefficients with the most temperature curves are around 0.9 during the period of 1852-1982 AD. In general, the temperature and the precipitation change synchronously in the Dulan region. It means that low temperature corresponds to low precipitation, and

Early summer temperature reconstruction in the eastern Tibetan plateau since ad 1440 using tree-ring width of Sabina tibetica

“…The warm periods 1624-1636, 1650-1668, and 1794-1804 are in good agreement with the March-May temperature reconstruction for the western Himalaya (Yadav et al 1999). The western Calibration period 1954-19801981-20061954-2006Verification period 1981-20061954-1980 The regression equation is in the form of y=a+bx, where y denoted the mean May-June temperature, x equaled the value of the ring-width chronology, a and b are the constants a LOOCV represents leave-one-out cross-validation (Michaelsen 1987) **Stands for the significant level of 0.01 Himalayan record also shows cool conditions identified in our reconstruction during 1440-1454, 1515-1527, and 1922-1937 periods. A regional tree-ring width chronology of S. tibetica for the Qamdo area (Bräuning 2001), which had negative correlations with temperature from March to June of the growth year, indicated relatively higher growth rates during 1490-1500, 1570-1580, and 1780-1790 periods.…”

“…This is in agreement with earlier studies (Bräuning 2001;Shi et al 2010;Wang et al 2008) on the same species from the eastern, central, and southwestern TP. Negative influences of early summer warmth on tree growth were reported for S. przewalskii on the northeastern TP (Gou et al 2008;Liang et al 2010;Liu et al 2006;Shao et al 2010;Sheppard et al 2004;Zhang et al 2003). In the western Himalayas, warm summers also limit the growth of Juniperus polycarpos (Yadav et al 2010), Cedrus deodara (Yadav et al 1997(Yadav et al , 1999Yadav et al 2004) and Abies pindrow (Hughes 1992).…”

“…Tree rings, as an annually resolved proxy record, have been increasingly used to reconstruct past climate changes on the TP (e.g., Bräuning and Mantwill 2004;Gou et al 2008;Liang and Eckstein 2009;Liang et al 2008;Liu et al 2007;Liu et al 2006;Shao et al 2005;Shi et al 2010;Wang et al 2009;Yang et al 2009;Yin et al 2008;Zhang et al 2003;Zhu et al 2008). For example, Liu et al (2007) reconstructed winter temperature variations since AD 1000 for the middle Qilian Mountains using Sabina przewalskii.…”

A 3,500-year tree-ring record of annual precipitation on the northeastern Tibetan Plateau

“…The interpretation of a dominant moisture control on tree growth in this region is supported by a number of previous studies (16,(19)(20)(21)(22). Interpreting local tree growth for this species as a predominant response to interannual variability of prior July to current-year June precipitation is consistent with the results of refs.…”

Periodic temperature-associated drought/flood drives locust plagues in China

“…Paleoclimatic studies using ice core records in the Kunlun Mountains ( Yao et al 2000), pollen profiles from Qinghai Lake (Kong et al 1992) or tree rings in the northeastern Tibetan Plateau (Liu et al 2006) documented a positive correlation between precipitation and temperature in China over the past one or two millennia. Global warming may increase precipitation in China through enhanced land-ocean water circulation by intensifying the land-sea thermal gradient during boreal summer ( Webster et al 1998).…”