Tree-ring reconstructed summer temperature anomalies for temperate East Asia since 800 C.E.
We develop a summer temperature reconstruction for temperate East Asia based on a network of annual tree-ring chronologies covering the period 800–1989 C.E. The East Asia reconstruction is the regional average of 585 individual grid point summer temperature reconstructions produced using an ensemble version of point-by-point regression. Statistical calibration and validation tests indicate that the regional average possesses sufficient overall skill to allow it to be used to study the causes of temperature variability and change over the region. The reconstruction suggests a moderately warm early medieval epoch (ca. 850–1050 C.E.), followed by generally cooler ‘Little Ice Age’ conditions (ca. 1350–1880 C.E.) and 20th century warming up to the present time. Since 1990, average temperature has exceeded past warm epochs of comparable duration, but it is not statistically unprecedented. Superposed epoch analysis reveals a volcanic forcing signal in the East Asia summer temperature reconstruction, resulting in pulses of cooler summer conditions that may persist for several years. Substantial uncertainties remain, however, particularly at lower frequencies, thus requiring caution and scientific prudence in the interpretation of this record.
KeywordsPaleoclimate Temperature Asia Tree-rings Volcanic
CRU TS 3.1 data are available from http://badc.nerc.ac.uk/data/cru. Two Asia2k Workshops held in Nagoya, Japan and Chiang Mai, Thailand were supported by PAGES, Nagoya University, and a grant to TN from the Research Institute for Humanity and Nature in Japan. ERC, KJA and BMB acknowledge the support of the US National Science Foundation (ATM 04-02474 and GEO 09-08971). Lamont-Doherty Earth Observatory Contribution No. 7638.
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