Rainfall, Ecosystems, and Fire in Warm Late Neogene Climates of the Lake Baikal Region

气候变化使严重干旱和长时间热浪更加常见，从而引发野火。这些大火摧毁了西伯利亚和加拿大的当地社区，同时用烟雾覆盖了西伯利亚，加拿大，西欧和美国的大城市。此外，北方地区在土壤中储存了大量的碳，如果释放到大气中，将加速全球变暖。北方森林的频繁野火通过将森林转变为草原和加速永久冻土融化而导致碳释放。气候模型预测，到21世纪末，西伯利亚的大部分地区将发生巨大的生态系统变化，北方森林将被广阔的草原所取代，一个新的温带落叶林生态系统将占据西伯利亚的大部分地区。然而，野火的区域差异和卫星观测的短时间跨度使得很难验证这些模型预测。该项目利用地球过去的温暖时期来测试气候模型对西伯利亚温暖气候下的水文气候、火灾和植被覆盖的预测，例如预计到21世纪世纪末。模型将通过与过去840万年来的气候，植被和野火记录进行比较来进行测试，这些记录保存在俄罗斯贝加尔湖的钻孔岩心中的有机和矿物化石中。该项目的主要目的是产生这种新的古气候记录。这项研究的更广泛影响是，模型的验证将使人们能够更准确地预测未来的碳排放以及西伯利亚未来几十年的人类宜居性和经济潜力，这对地区安全可能产生影响。该项目还将支持本科生在联邦指定的西班牙裔服务机构的研究经验。该项目将测试两个假设，基于气候模型预测和最近的气候和野火趋势的研究。第一，生长季节延长，降水量更均匀，在西伯利亚温暖的气候条件下，将测试配对分析植物蜡氢同位素（降水同位素代理）和支链甘油二烷基甘油四醚（温度代理）。第二，在贝加尔湖地区的火灾制度是温度，水文气候和生物群落的函数，将进行测试的多环芳烃和木炭（火代理）在相同的样品作为植物蜡氢同位素和支链甘油二烷基甘油四醚测量配对分析。这些数据的时间序列将揭示过去840万年来西伯利亚气候、植被和野火对全球气候趋势的区域响应。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Climate change makes acute droughts and prolonged heat waves that stimulate wildfires more common. These fires have devasted local communities in Siberia and Canada while blanketing large municipalities in Siberia, Canada, Western Europe, and the United States with smoke. Furthermore, boreal regions store huge amounts of carbon in soils that, if released to the atmosphere, would accelerate global warming. Frequent wildfires in boreal forests lead to carbon release by shifting forest to grasslands and by accelerating permafrost melt. Climate models predict dramatic ecosystem changes, with boreal forests replaced by extensive grasslands and a new temperate deciduous forest ecosystem occupying much of Siberia by the end of the 21st century. However, regional differences in wildfires and the short time span of satellite observations make it difficult to verify these model predictions. This project uses warm periods in Earth’s past to test climate model predictions of hydroclimate, fire and, vegetation cover in Siberia in warm climates, such as expected by the end of the 21st century. Models will be tested by comparison to a record of past climate, vegetation, and wildfire over the past 8.4 million years that is preserved in organic and mineral fossils in a drillcore from Lake Baikal, Russia. The primary purpose of this project is the generation of this new paleoclimate record. The broader impacts of this study are that validation of models will make possible more accurate forecasts of future carbon emission as well as the human habitability and economic potential of Siberia in coming decades, with potential ramifications for regional security. The project will also support undergraduate research experiences at a federally designated Hispanic-serving institution.This project will test two hypotheses, based upon climate model predictions and studies of recent climate and wildfire trends. The first, that growing season lengthens and precipitation is more equable in Siberia under warm climate conditions, will be tested by paired analyses of plant-wax hydrogen isotopes (precipitation isotope proxy) and branched glycerol dialkyl glycerol tetraethers (temperature proxy). The second, that fire regime in the Lake Baikal region is a function of temperature, hydroclimate, and biome, will be tested by paired analyses of polycyclic aromatic hydrocarbons and charcoal (fire proxies) in the same samples as the plant-wax hydrogen isotope and branched glycerol dialkyl glycerol tetraether measurements. Timeseries of these data will reveal the regional response of climate, vegetation, and wildfires in Siberia to global climate trends over the past 8.4 million years.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.