Light absorbing particles in the cryosphere: occurrence, impacts, and participatory decision-making
Creators: name: Cintron Rodriguez, Isatis M.
Publisher: name: No Publisher Supplied
Year: 2023

description: The cryosphere consists of the frozen water and permafrost in the earth system. As a result of the current climate crisis, the cryosphere is undergoing major changes. The Arctic, containing important features of the cryosphere, is the fastest warming region in the world. Arctic glaciers and the Greenland Ice Sheet have started to experience an increase in mass loss rates leading to enhanced sea level rise contribution. Continued sea level rise through the 21st century will have wide-reaching impacts on the livelihoods of millions of people, especially those living in low-lying coastal areas. Understanding the different drivers of physical change in the Arctic is therefore important to accurately predict future climate conditions and identify effective climate justice policies. The Arctic mass loss is driven by temperature, albedo perturbations, and cloud cover and feedbacks. Some of the Arctic albedo change drivers are light absorbing particles (LAP), which include black carbon (BC), brown carbon (BrC), mineral dust, volcanic ash, and snow algae. However, observations of occurrence, sources, and magnitude of impacts of LAP across the cryosphere system remain scarce. Additionally, understanding the way LAP drive albedo changes is also underdeveloped. LAP radiative forcing is controlled by complex interactions and feedbacks over the Earth system that affect snow and cloud microphysics. This thesis expands the understanding of the LAP feedbacks and interactions in the cryosphere. The first part of this thesis characterizes LAP occurrence and its influence on snow albedo through the combined effect of surface darkening and snow metamorphism. Here, I find that LAP snow-aging feedback results in albedo reductions 3-8 times larger than previous studies associated with LAP alone have shown. In the second part, this thesis evaluates the connection between LAP and total particulate ability to enable the formation of ice crystals in clouds, or ice nucleation activity (INA). Although the glaciation in mixed-phase clouds, which represent more than half of Arctic clouds, are influenced by various parameters (temperature, updraft velocity, etc.) ice nuclei play a critical role in enabling their formation. As each particle has different INA, mixed-phased clouds are influenced both by particle availability and characteristics of the aerosol. As dust is believed to be the most important type of ice nuclei and Iceland is the main source of high latitudes dust transport, we investigate LAP INA in Iceland. I find that methanol-soluble organic aerosols have a more important role in INA than BC or high latitude dust. Furthermore, BC and dust, can potentially inhibit methanol-soluble organic aerosol INA and therefor impact precipitation patterns. This also means methanol-soluble organic aerosol internal snow mixing must also be quantified and further characterized to fully constrain LAP effects on snow albedo. The third part of this thesis focuses on LAP trends in the Arctic and their potential sources by analyzing LAP, major ions, and trace elements over the past 25 years. I analyze the snow chemistry observed in Greenland using both snow measurements and analysis of a shallow ice core. My results indicate dust and long-range transport are important aerosol sources in the Arctic. The combination of these three studies in this thesis contribute to our understanding of LAP impacts over the Arctic, specifically the Greenland ice sheet and Iceland glaciers. These studies can help improve climate models regional projections by providing better parameterizations of LAP feedbacks and snow chemistry. Understanding the impacts and some of the potential sources of LAP can pave the way for establishing mitigation policies for Short lived climate forcers (SLCF), which includes LAP. However, we must ensure that those policies are transformational and just. To this end, this dissertation provides a framework for participatory decision-making to better equip those tasked with designing and implementing climate public policy. Transformative and just mitigation policies depend on informed and active citizenship, this is the spirit of Action for Climate Empowerment (ACE), Art 12 of the Paris Agreement. Here, we developed and proved a novel approach, combining backcasting and Talanoa dialogue, to facilitate widespread buy-in from key stakeholders while fostering justice in climate change policy making. National ACE strategies that ensures informed participation in decision making, underpins all climate action will enable and catalyze climate action on all fronts – everything, everywhere all at once.