The Last Glacial Termination in Southern Middle Latitudes

中纬度南部地区最后一次冰川终止

• 批准号: 1102782
• 负责人: George Denton
• 金额: $ 39.38万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1102782&HistoricalAwards=false
• 关键词: Last; Glacial; Termination; Southern; Middle

The spectacular termination that marked the end of the last major ice age represents the largest and most rapid natural climate change in Earth's recent history. Identifying the conditions and processes that led to this termination requires detailed chronologies of sensitive paleoclimate proxies that monitor the last glacial/interglacial transition across the globe. This grant will develop such a chronology in the middle latitudes of the Southern Hemisphere for the reduction of ice volume in the Southern Alps of New Zealand from the last glacial maximum to today?s conditions. Our chronology will be based on newly developed state-of- the-art 10Be surface-exposure dating of glacial landforms produced during this reduction. This grant will determine if the Antarctic deglacial signal extents to middle latitudes of the Southern Hemisphere, thus setting up a test of a recent hypothesis that the Principal Investigator published in Science. The hypothesis posits that large Northern Hemisphere ice sheets, triggered by rising summer sunshine, produced a self-sustaining flood of icebergs and melt water into the North Atlantic, leading to cold northern stadial conditions that altered the global meridional temperature gradients which in turn regulated the major global zonal wind systems. A poleward shift and/or intensification of the Southern Hemisphere westerlies warms the Southern Hemisphere from middle latitudes to Antarctica and purges enough CO2 to the atmosphere by Southern Ocean upwelling to maintain interglacial conditions worldwide. Because New Zealand glaciers lie in middle latitudes near the outer boundary of the Southern Ocean, this hypothesis predicts that their volume loss should correlate with the Antarctic warming pulse and should be in antiphase with the northern stadial triggered by freshwater influx into the North Atlantic. This research will date ice recession in New Zealand?s Southern Alps and thus test this prediction.Present-day global warming is front-page news. But scientists still do not fully understand the underlying mechanisms that caused the great global warming that ended the last ice age and produced the interglacial conditions of the last 11,700 years, during which human civilization and population has developed. The team has developed a hypothesis of how this great warming was achieved. The grant will produce knowledge of the timing of Southern Hemisphere events to test the hypothesis. This test involves recognition of changes in wind belts and ocean circulation that accompany a shift in the temperature gradient between hemispheres. A shift in the interhemispheric temperature gradient is also expected shortly, as rising atmospheric CO2 is predicted to warm the Southern less than the Northern Hemisphere. Thus, by studying the past great warming, we may be able to anticipate how such changes may occur during the ongoing global warming.

标志着最后一个主要冰河时代结束的壮观终止代表了地球近代历史上最大和最迅速的自然气候变化。 确定导致这种终止的条件和过程需要详细的敏感的古气候代理年表，监测整个地球仪的末次冰期/间冰期的过渡。这笔赠款将在南半球中纬度地区开发这样一个年表，用于减少新西兰南阿尔卑斯山的冰量，从最后一次冰期到今天？的条件。我们的年表将基于新开发的国家的最先进的10 Be表面暴露测年的冰川地貌在此减少。这笔赠款将确定南极冰川消退信号是否延伸到南半球的中纬度地区，从而对首席研究员在《科学》杂志上发表的一项最新假设进行测试。该假说认为，夏季阳光上升引发的北方半球大冰盖产生了一股自我维持的冰山和融水洪水，流入北大西洋，导致北方寒冷的天气条件改变了全球纬向温度梯度，进而调节了主要的全球纬向风系统。南半球西风带的向极移动和/或增强使南半球从中纬度到南极洲变暖，并通过南大洋上涌向大气中清除足够的二氧化碳，以维持全球间冰期的条件。由于新西兰冰川位于南大洋外边界附近的中纬度地区，这一假说预测，它们的体积损失应与南极变暖脉冲相关，并应与淡水流入北大西洋所引发的北方视距反相。这项研究将日期冰衰退在新西兰？现在全球变暖是头版新闻。但科学家们仍然没有完全理解导致全球变暖的根本机制，全球变暖结束了最后一个冰河时代，并产生了过去11,700年的间冰期条件，在此期间，人类文明和人口得到了发展。该团队已经提出了一个关于这种巨大变暖是如何实现的假设。这项资助将产生南半球事件发生时间的知识，以检验这一假设。这项测试涉及到识别风带和海洋环流的变化，这些变化伴随着两半球之间温度梯度的变化。由于预计大气中二氧化碳浓度的上升对南半球的升温程度低于对北方的升温程度，因此预计半球间的温度梯度也将在短期内发生变化。 因此，通过研究过去的大变暖，我们可能能够预测在持续的全球变暖期间这些变化可能会发生。