Doctoral Dissertation Research: Global Fire Since the Last Glacial Maximum

近年来，世界许多地区的野火活动异常极端。火灾制度的这些大范围变化对人类健康、生态系统和全球气候系统构成了重大威胁。没有长期的全球火灾历史数据，很难理解这些变化是如何发生的，以及为什么会发生。卫星图像、历史记录和树状年代学数据已被用来创建持续时间长达100年的短历史，但不存在较长时间段的空间上明确的合成。这项博士论文研究项目将汇编和合成已发表的木炭数据，以重建自上一次冰川高峰期以来的全球火灾活动。这位博士生将研究逐渐和突然气候变化期间生物质燃烧的变化，并比较古火灾和花粉数据，以研究长期的火灾、植被和气候动态。更具体地说，她将创建一个跨越过去21,000年的木炭古火记录的全球数据库；对集中在北美的最高分辨率古火记录进行荟萃分析；整合北美的木炭和花粉数据，以检查不断变化的气候条件下的火和燃料关系；并利用观测和模拟的古火数据，对上一次冰川最大时期和全新世中期的火灾活动进行全球数据模型比较。这项研究的结果将加强对火灾活动的空间和时间模式以及自上一次冰川最大时期以来火灾制度发生重大变化背后的机制的基本了解。对高分辨率木炭数据和花粉数据的详细分析将为火灾制度变化的特定维度提供新的见解，例如火灾频率与火灾严重程度如何在气候和植被梯度之间变化。数据-模型比较将验证植被-火耦合模型，并为测试关于火、气候、植被和人类活动之间相互作用的假设提供一个新的工具。数据将与由美国国家海洋和大气局世界古气候学数据中心赞助的国际多代理古火灾数据库共享。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

Wildfire activity has been unusually extreme in many parts of the world in recent years. These broadscale changes in fire regimes pose a significant threat to human health, ecosystems, and the global climate system. It is difficult to understand how and why these changes are occurring without long-term, global fire-history data. Satellite images, historical records, and dendrochronological data have been used to create short histories of up to 100 years in duration, but no spatially explicit syntheses exist for longer time periods. This doctoral dissertation research project will compile and synthesize published charcoal data to reconstruct global fire activity since the last glacial maximum. The doctoral candidate will examine changes in biomass burning during periods of both gradual and abrupt climate change and compare paleofire and pollen data to investigate long-term fire, vegetation, and climate dynamics. More specifically, she will create a global database of charcoal-based paleofire records that spans the last 21,000 years; perform a meta-analysis of the highest-resolution paleofire records, which are concentrated in North America; integrate charcoal and pollen data from North America to examine fire and fuel relationships under changing climate conditions; and use observed and simulated paleofire data to make a global data-model comparison of fire activity at the time of the last glacial maximum and during the mid-Holocene.Results from this study will enhance basic understanding of the spatial and temporal patterns of fire activity and of the mechanisms behind major shifts in fire regimes that have occurred since the last glacial maximum. The detailed analysis of high-resolution charcoal data and pollen data will provide new insights into specific dimensions of fire-regime changes, such as how fire frequency versus fire severity have varied across climate and vegetation gradients. The data-model comparisons will validate a coupled vegetation-fire model and provide a new tool for testing hypotheses about interactions between fire, climate, vegetation and human activities. Data will be shared with the International Multiproxy Paleofire Database sponsored by the World Data Center for Paleoclimatology at NOAA. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.