Dendrochronological Paleoclimate Reconstruction for Monsoon Asia

为了重建亚洲季风区过去500年的古气候，我们在堪察加半岛、日本、老挝和尼泊尔喜马拉雅地区的32个地点进行了一系列古树增量核的实地搜索和后续取样，从大约900棵树中获得了大约1800个增量核。最长的岩心来自老挝北部的表观年龄超过1000年的hodginsii。通过对各采样点环宽变化对当地气候的响应进行一系列分析，并利用特定采样点的传递函数转换环宽指数，重建了尼泊尔东部300年、尼泊尔西部285年、堪察加中部420年、堪察加南部210年和日本四国岛240年的古气候。由于样本数量有限和或多或少模糊的年轮，老挝北部700年的重建工作尚未完成。对这些局部重建的比较表明，早在两个世纪前，堪察加半岛就明确出现了全球变暖的区域综合趋势，后来又不那么明确地向南显现，最终在喜马拉雅山脉几乎不存在。过去全球变暖的这种区域趋势与预估的未来高纬度地区肯定变暖的趋势是一致的，而低纬度地区的气温将越来越低。

With an objective of reconstructing paleoclimate over the past 500 years diagonally across Monsoon Asia, a series of field search for and subsequent increment core sampling from old trees was conducted at a total of 32 sites in Kamchatka Peninsular, Japan, Laos and the Nepal Himalayas, resulting in a total of some 1800 increment cores from some 900 individual trees. The longest core was obtained from Fokienia hodginsii of apparent age of over 1000 years located in Northern Laos.A series of analysis of ring-width variation in response to local climate for each sampling site and subsequent conversion of ring-width index using site specific transfer functions resulted in paleoclimate reconstruction of past 300 yrs for Eastern Nepal, 285 yrs for Western Nepal, 420 yrs for Central Kamchatka, 210 yrs for Southern Kamchatka and 240 yrs for Island of Shikoku, Japan. The 700-yrs reconstruction for Northern Laos is yet to come due to difficulty from limited number of samples and more or less obscure rings. Comparison of these local reconstructions revealed a regionally integrated trend of global warming appearing definitely and as early as two centuries ago in Kamchatka to show later and less definitely southward, ending up virtually no existent in the Himalayas. This regional trend of the past global warming is consistent with projected future trend of definite warming in higher latitudes with increasingly less warring in lower latitudes.