Collaborative Research: Bugs to clouds: Thawing permafrost, its microbes, and their possible role in Arctic climate feedbacks

在一个更温暖的世界里，北极预计将变得更加多云和多雨。由于北极变暖的速度是世界其他地区的两倍多，因此云层的变化可能会影响海冰的范围，永久冻土的融化以及区域和全球天气。然而，北极云的形成和演变仍然高度不确定，部分原因是对称为气溶胶的空气传播粒子的了解有限，气溶胶是云的种子，特别是形成云冰晶的气溶胶。这些冰晶，称为冰成核颗粒或INPs，可以来自土壤，植物，海洋，湖泊和河流。特别是，来自地球生物群落的INPs的来源和丰度知之甚少，但可能是云冰形成的关键。气温升高也引发了高纬度地区快速而广泛的永久冻土融化，这对生活在这些地区的社区和野生动物产生了影响。永久冻土的融化还会释放温室气体，促进细菌等微生物的代谢活动，这表明了一种有趣的可能性，即随着永久冻土的融化，微生物本身及其副产品可能会被释放到湖泊、河流和海洋中，并可能进入大气层，影响云的形成。然而，永久冻土以前没有被评估为云的种子来源。由于永久冻土覆盖了大约15%的北方的土地，这种新的，但潜在的广泛的INP源可能是重要的预测北极clouds.The总体假设的这个项目是，INPs释放融化永久冻土显着影响云的性质在北极。被称为ARCSPIN（北极永久冻土冰成核研究）的实地部署涉及在阿拉斯加北坡的两个NSF支持的设施中收集和测量永久冻土土壤，湖水，河水和气溶胶中的INPs。此外，这项研究利用现有的NSF船载机会，从白令海和楚科奇海收集气溶胶和海水样本，用于INPs。陆基测量提供了一个详细的评估永久冻土INP源，而船载测量澄清的空间范围等INPs。研究人员使用气候和地球系统模型将陆地和海洋环境中的观测联系在一起，并评估永久冻土INPs形成的云对更广泛的北极地区阳光和热量的影响。通过跨学科的方法评估物理、生物和大气气候系统过程之间的相互作用，拟议的联合观测-模拟研究推进了对北极作为一个耦合系统的理解。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。

In a warmer world, the Arctic is projected to become cloudier and rainier. As the Arctic warms more than twice as fast as the rest of the world, resulting changes in clouds can subsequently affect sea ice extent, permafrost thaw, and regional and global weather. However, the formation and evolution of Arctic clouds remain highly uncertain in part due to a limited understanding of airborne particles known as aerosols that seed clouds, specifically aerosols that form cloud ice crystals. These ice crystals, called ice nucleating particles or INPs, can originate from soil, plants, oceans, lakes, and rivers. In particular, the sources and abundance of INPs from Earth’s biome are poorly understood yet may be crucial for cloud ice formation. Warmer temperatures are also triggering rapid and extensive permafrost thaw at high latitudes, which has implications for communities and wildlife living in these regions. Thawing permafrost additionally releases greenhouse gases and promotes metabolic activity in microbes such as bacteria—suggesting the intriguing possibility that as permafrost thaws, the microbes themselves and their byproducts could be released into lakes, rivers, and the ocean, and potentially into the atmosphere to impact cloud formation. However, permafrost has not been previously evaluated as a source of seeds for clouds. Because permafrost covers approximately 15% of Northern Hemisphere land, this novel but potentially widespread INP source may be important for predictions of Arctic clouds.The overarching hypothesis of this project is that INPs released from thawing permafrost significantly influence cloud properties in the Arctic. The field deployment called ARCSPIN (ARCtic Study of Permafrost Ice Nucleation) involves collection and measurement of INPs in permafrost soil, lake water, river water, and aerosols at two NSF-supported facilities on the North Slope of Alaska. Additionally, this study leverages existing NSF shipborne opportunities to collect aerosol and seawater samples from the Bering and Chukchi Seas for INPs. Land-based measurements provide a detailed assessment of permafrost INP sources, while the shipborne measurements clarify the spatial reach of such INPs. The researchers use climate and earth system models to tie together observations in terrestrial and marine environments, and to assess the effects of clouds formed by permafrost INPs on sunlight and heat in the broader Arctic region. The proposed joint observational-modeling study advances the understanding of the Arctic as a coupled system through an interdisciplinary approach to assess interactions among physical, biological, and atmospheric climate system processes.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.