P2C2: Collaborative Research: Defining the paleoclimate-fire relationship in CA across temporal scales through integrated monitoring, stalagmite studies, and proxy system modeling

尽管野火的频率和强度明显增加，但加州（CA）火灾、变暖和降雨变化之间的关系仍然知之甚少。该项目将确定过去7万年来加州过去气候变化与野火行为之间的关系。这将通过监测加州的洞穴和评估气候变化和洞穴矿藏中保存的野火证据来实现。这些被称为石笋的沉积物能够记录过去数千年到数十万年的环境变化。将开发一个将气候，洞穴和野火过程联系起来的环境模型，这将促进对气候和火灾信号如何在石笋中存档的理解。该模型还将被用来建立强大的重建的气候-火的关系，在个别洞穴网站和跨CA的洞穴横断面。总的来说，这项研究将有助于建立一个有凝聚力的画面，该地区的气候如何应对全球气候变化，包括变暖，以及这些变化如何影响野火行为。其他可交付成果包括所有石笋记录的开放式标准化数据库和社区可访问的软件。一群不同的早期职业科学家和本科生和研究生将通过该项目进行培训，使用纵向和横向综合培训和指导计划，“C3 -加利福尼亚州的气候变化”。该项目将测试三个假设，这些假设与调查加利福尼亚州火灾多发地区区域水文气候条件和野火之间关系的主要目标相关联，在不同的时间尺度和背景气候状态，包括没有或最小的人为影响的时期。这将通过解决四个研究目标来实现。首先，一个过程为基础的，“表面到石笋”的一套水文气候和火灾示踪剂的演变的理解将开发通过监测三个岩溶系统代表不同的气候条件在CA。该组件将进一步校准有前途的新代理（三角洲-44钙，87锶/86锶，和一套生物标志物），到目前为止，已被应用到少数岩溶系统。其次，将建立下一代多代理岩溶系统模型，该模型将利用现有的代理系统模型，并将水文气候和火灾代理机制与其环境和生态驱动因素套件联系起来。第三，一组可比的方解石，包体流体，生物标志物代理记录，包括新的水文和火灾代理，将开发十石笋，定义纬度和海岸到塞拉利昂内华达州在CA的横断面。第四，特定地点和区域代理模型的比较将使用贝叶斯反演产生数据驱动的定量重建的水文气候和火灾活动在CA在过去的70万年。总的来说，这项研究将为未来的气候建模工作提供基础，重点是限制美国西部水文气候变化和火灾活动的驱动因素。该奖项反映了NSF的法定使命，并被认为值得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来支持。

Despite observable increases in the frequency and intensity of wildfires, the relationship between fire, warming, and rainfall variability in California (CA) remains poorly understood. This project will define the relationship between past climate change and wildfire behavior in CA over the last 70,000 years. This will be accomplished by monitoring caves in CA and by assessing evidence of climate change and of wildfires preserved in cave mineral deposits. These deposits, called stalagmites, are capable of documenting past environmental changes continuously over 1000s to 10s of thousands of years. An environmental model that links climate, cave, and wildfire processes will be developed that will advance the understanding of how the climate and fire signals are archived in stalagmites. The model will also be used to build robust reconstructions of the climate-fire relationship at individual cave sites and for transects of caves across CA. Collectively, this research will contribute to building a cohesive picture of how climate in this region responds to global climate change, including warming, and how these changes influence wildfire behavior. Additional deliverables include an open-access, standardized database of all stalagmite records and community accessible software. A cohort of diverse early career scientists and undergraduate and graduate students will be trained through the project using a vertically and laterally integrated training and mentoring program, ‘C3 —Climate Change in California’.This project will test three hypotheses linked by the primary goal of investigating the relationship between regional hydroclimate conditions and wildfire in the fire-prone region of CA, over a variety of timescales and background climate states including periods with no or minimal anthropogenic influence. This will be accomplished by addressing four research objectives. First, a process-based, ‘surface-to-stalagmite’ understanding of the evolution of a suite of hydroclimate and fire tracers will be developed through monitoring of three karst systems representative of different climate conditions in CA. This component will further calibrate promising new proxies (delta-44Ca, 87Sr/86Sr, and a suite of biomarkers) that to date have been applied to few karst systems. Second, a next-generation, multi-proxy karst system model will be built that leverages existing proxy system models and links hydroclimate and fire proxies mechanistically to their suite of environmental and ecologic drivers. Third, a comparable set of calcite, inclusion-fluid, and biomarker proxy records, including novel hydrologic and fire proxies, will be developed for ten stalagmites that define latitudinal and coastal-to-Sierra Nevada transects in CA. Fourth, site-specific and regional proxy-model comparisons will be carried out using Bayesian inversion to produce data-driven quantitative reconstructions of the hydroclimate and fire activity in CA over the past 70 ka. Collectively, this research will provide the basis for future climate modeling efforts focused on constraining the drivers of hydroclimate change and fire activity in the western U.S.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.