Warming-induced northwestward migration of the East Asian monsoon rain belt from the Last Glacial Maximum to the mid-Holocene
Warming-induced northwestward migration of the East Asian monsoon rain belt from the Last Glacial Maximum to the mid-Holocene
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DOI：
10.1073/pnas.1504688112
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发表时间：
2015-10
期刊：
影响因子：
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通讯作者：
Shiling Yang;Z. Ding;Yangyang Li;Xu Wang;Wenying Jiang;Xiaofang Huang
中科院分区：
文献类型：
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作者：
Shiling Yang;Z. Ding;Yangyang Li;Xu Wang;Wenying Jiang;Xiaofang Huang
东亚季风雨带的南移加剧了对中国北方变暖引起的干旱的关注。黄土高原古植被的变化为未来气候变化提供了新的思路。我们发现，C4植物生物量的空间分布是一个强大的模拟季风雨带，迁移至少300公里的西北部从寒冷的末次冰期最大（1019 ka）到温暖的全新世（104 ka）。这些结果有力地支持了地球热赤道在全球变暖时将向北移动的观点，以及在过去几十年中观测到的季风雨带南移是短暂的，随着全球变暖的推进，中国北方最终将变湿。黄土高原C3/C4植被分布的冰期-间冰期变化与东亚夏季风的强度和位置有关，并可能为全球变暖引起的未来变化提供见解。本文报道了黄土高原21个黄土剖面末次盛冰期以来有机质的δ 13 C记录。各剖面δ 13 C值（-25‰ ~-16‰）从末次盛冰期到中全新世逐渐增大，在各时段内从西北向东南逐渐增大。在末次盛冰期，C4生物量从东南部的40%增加。末次盛冰期和全新世中期C4生物量的空间格局与现代暖季降水非常相似，因此可以作为当代东亚夏季季风雨带的一个强有力的模拟。利用冷末次盛冰期C4生物量10-20%等值线作为参考，我们得出了暖全新世季风雨带向西北迁移至少300公里。我们的研究结果有力地支持了地球热赤道将在一个更温暖的世界中向北移动的预测。随着全球变暖的继续，过去几十年在中国北方观测到的季风雨带南移和干燥趋势将很快逆转。
Significance The southward displacement of the East Asian monsoon rain belt heightens concerns over the warming-induced drying of northern China. Paleovegetation change on the Chinese Loess Plateau provides insights into future climate changes. We find that the spatial distribution of C4 plant biomass is a robust analog for the monsoon rain belt, which migrated at least 300 km to the northwest from the cold Last Glacial Maximum (∼19 ka) to the warm Holocene (∼4 ka). These results strongly support the idea that the Earth's thermal equator will move northward in a warmer world, and that the observed southward migration of the monsoon rain belt over the last few decades is transient and northern China will eventually become wet as global warming advances. Glacial–interglacial changes in the distribution of C3/C4 vegetation on the Chinese Loess Plateau have been related to East Asian summer monsoon intensity and position, and could provide insights into future changes caused by global warming. Here, we present δ13C records of bulk organic matter since the Last Glacial Maximum (LGM) from 21 loess sections across the Loess Plateau. The δ13C values (range: –25‰ to –16‰) increased gradually both from the LGM to the mid-Holocene in each section and from northwest to southeast in each time interval. During the LGM, C4 biomass increased from 40% in the southeast. The spatial pattern of C4 biomass in both the LGM and the mid-Holocene closely resembles that of modern warm-season precipitation, and thus can serve as a robust analog for the contemporary East Asian summer monsoon rain belt. Using the 10–20% isolines for C4 biomass in the cold LGM as a reference, we derived a minimum 300-km northwestward migration of the monsoon rain belt for the warm Holocene. Our results strongly support the prediction that Earth's thermal equator will move northward in a warmer world. The southward displacement of the monsoon rain belt and the drying trend observed during the last few decades in northern China will soon reverse as global warming continues.