Reconstruction of the regional summer ground surface temperature in the permafrost region of Northeast China from 1587 to 2008.

To extend the historical temperature record in the permafrost region of Northeast China, we reconstruct the regional ground surface temperature (GST) for the past four centuries based on a network of Dahurian larch (Larix gmelinii Rupr.) tree-ring width chronologies. Seven standard tree-ring chronologies, which correlate well with each other, are averaged to create a regional mean chronology. GST is the major limiting factor for tree growth in this region. The optimum range of GSTs is from 30 May to 26 August (summer GST), identified by combining the days on which tree growth was strongly influenced by the daily GST data. The summer GST was significantly correlated with the regional mean chronology (r = 0.704, p < 0.001) over the common period 1971-2008 and was reconstructed for the period 1587-2008. The reconstructed GST accounts for 49.4% of the actual variance in the GST over the period 1971-2008 and captures four warm periods (1597-1603, 1716-1723, 1781-1788, and 1925-1929) and three cold periods (1639-1647, 1686-1711, and 1799-1805). The reconstructed GST is consistent with the northern hemisphere temperature in the Little Ice Age, and the warming rate from 1857 to 2008 is similar to a previously reported temperature reconstruction in the Xiao Xing’an Mountains. The low frequency of the reconstructed GST is well matched with that of the permafrost thawing depth. The reconstructed GST represents the longest temperature record in this study region and may be used as a reference for the permafrost thawing depth. [ABSTRACT FROM AUTHOR]