A 2,300-year-long annually resolved record of the South American summer monsoon from the Peruvian Andes
A 2,300-year-long annually resolved record of the South American summer monsoon from the Peruvian Andes
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DOI：
10.1073/pnas.1003719108
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发表时间：
2011-05-24
影响因子：
11.1
通讯作者：
Rosenmeier, Michael F.
中科院分区：
文献类型：
--
作者：
Bird, Broxton W.;Abbott, Mark B.;Rosenmeier, Michael F.
利用秘鲁中部安第斯山脉一个变形湖的自生方解石降水记录，详细描述了过去2300年南美夏季风降水的年代际和百年平均状态变化。这一独特的沉积物记录表明，O-18三角洲在公元900年至1100年的中世纪气候异常(MCA)期间达到顶峰，为SASM在此期间显著减弱提供了证据。最小的O-18值出现在公元1400年至1820年之间的小冰期(LIA)，反映了SASM在区域上同步的长期加强。LIA之后，O-18增量迅速增加，特别是在当前的暖期(CWP；公元1900年至今)，表明SASM降水的减少比MCA开始时更突然和更持久。MCA和CWP路径期间SASM降水的减少重建了北半球和北大西洋的变暖，以及热带辐合带(ITCZ)在大西洋，可能是太平洋上空的北移。LIA期间SASM降水的加强是在重建的北半球和北大西洋冷却、太平洋类似厄尔尼诺的变暖以及两个大洋上的ITCZ南移之后进行的。这些结果表明，SASM平均状态变化对ITCZ变率很敏感，这是由西半球热带海温，特别是大西洋热带海温所调节的。因此，北半球和北大西洋持续变暖可能有助于延续过去100年来南方共同市场降水减少的趋势，这将对安第斯山脉的水资源产生不利影响。
Decadal and centennial mean state changes in South American summer monsoon (SASM) precipitation during the last 2,300 years are detailed using an annually resolved authigenic calcite record of precipitation delta O-18 from a varved lake in the Central Peruvian Andes. This unique sediment record shows that delta O-18 peaked during the Medieval Climate Anomaly (MCA) from A. D. 900 to 1100, providing evidence that the SASM weakened considerably during this period. Minimum delta O-18 values occurred during the Little Ice Age (LIA) between A. D. 1400 and 1820, reflecting a prolonged intensification of the SASM that was regionally synchronous. After the LIA, delta O-18 increased rapidly, particularly during the current warm period (CWP; A. D. 1900 to present), indicating a return to reduced SASM precipitation that was more abrupt and sustained than the onset of the MCA. Diminished SASM precipitation during the MCA and CWP tracks reconstructed Northern Hemisphere and North Atlantic warming and a northward displacement of the Intertropical Convergence Zone (ITCZ) over the Atlantic, and likely the Pacific. Intensified SASM precipitation during the LIA follows reconstructed Northern Hemisphere and North Atlantic cooling, El Nino-like warming in the Pacific, and a southward displacement of the ITCZ over both oceans. These results suggest that SASM mean state changes are sensitive to ITCZ variability as mediated by Western Hemisphere tropical sea surface temperatures, particularly in the Atlantic. Continued Northern Hemisphere and North Atlantic warming may therefore help perpetuate the recent reductions in SASM precipitation that characterize the last 100 years, which would negatively impact Andean water resources.