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.

气候变化使得引发野火的严重干旱和持续热浪变得更加常见，这些火灾摧毁了西伯利亚和加拿大的当地社区，同时笼罩了西伯利亚、加拿大、西欧和美国的大城市。此外，北方地区还蕴藏着巨大的烟雾。土壤中的碳如果释放到大气中，就会加速全球变暖。北方森林频繁发生的野火会导致森林向草原转移，并加速永久冻土融化，从而导致碳排放。气候模型预测，生态系统会急剧融化。到21世纪末，北方森林被广阔的草原所取代，新的温带落叶森林生态系统占据了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时间跨度较短，使得这些模型的预测难以验证。该项目利用地球过去的温暖时期来测试气候模型对温暖气候下西伯利亚的水文气候、火灾和植被覆盖的预测，例如模型预计到 21 世纪末的情况。通过与俄罗斯贝加尔湖钻芯中保存的有机和矿物化石中保存的过去 840 万年的气候、植被和野火记录进行比较来测试该项目的主要目的是生成这种新的。这项研究的更广泛影响是，模型的验证将使对未来几十年的碳排放以及西伯利亚的人类居住性和经济潜力进行更准确的预测，该项目还将对区域安全产生潜在影响。支持联邦政府指定的西班牙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近期气候和野火趋势的研究来测试两个假设。第一个假设是，在温暖的情况下，西伯利亚的生长季节延长，降水更加均匀。气候条件下，将通过植物蜡氢同位素（沉淀同位素代理）和支链甘油二烷基甘油四醚（温度代理）的配对分析进行测试。第二，湖中的火灾状况。贝加尔湖地区是温度、水文气候和生物群落的函数，将通过对与植物蜡氢同位素和支链甘油二烷基甘油四醚测量相同的样品中的多环芳烃和木炭（火代理）进行配对分析来进行测试。这些数据将揭示过去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反应。该奖项反映了通过使用基金会的智力价值和更广泛的影响审查标准进行评估，NSF 的法定使命被认为值得支持。