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

贝加尔湖地区新第三纪温暖气候下的降雨、生态系统和火灾

• 批准号: 2202918
• 负责人: Pratigya Polissar
• 金额: $ 38.01万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2202918&HistoricalAwards=false
• 关键词: Rainfall; Ecosystems; Fire; Warm; Late

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.

气候变化使引发野火的严重干旱和长期热浪变得更加常见。这些大火摧毁了西伯利亚和加拿大的当地社区，同时西伯利亚、加拿大、西欧和美国的大城市被浓烟笼罩。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。北方森林频繁的野火通过将森林转移到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，北方森林将被大片草原取代，新的温带落叶森林生态系统将占据西伯利亚的大部分地区。然而，野火的地区差异和卫星观测的短时间跨度使得验证这些模型预测变得困难。该项目使用地球过去的暖期来测试气候模型对西伯利亚温暖气候下的水气候、火和植被覆盖的预测，例如预计到21世纪末。模型将通过与过去840万年来气候、植被和野火的记录进行比较来测试，这些记录保存在俄罗斯贝加尔湖钻探岩芯的有机和矿物化石中。该项目的主要目的是产生这一新的古气候记录。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，以及未来几十年西伯利亚的人类宜居性和经济潜力，这可能会对区域安全产生影响。该项目还将支持在联邦指定的拉美裔服务机构的本科生研究经验。该项目将基于气候模型预测和对最近气候和野火趋势的研究来检验两个假说。首先，西伯利亚的生长季延长，降水在温暖的气候条件下更加均匀，这将通过植物蜡氢同位素(降水同位素替代品)和支链甘油二烷基甘油四醚(温度替代品)的配对分析来检验。第二，贝加尔湖地区的火灾状况是温度、水文气候和生物群的函数，将通过对植物蜡氢同位素和支链甘油二烷基甘油四醚测量样品中的多环芳烃和木炭(火灾替代品)的配对分析来测试。这些数据的时间序列将揭示过去840万年来西伯利亚地区气候、植被和野火对全球气候趋势的区域响应。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。