PHY Seminar: Aerosols and their Gaming of the Climate System: Microscale presence to Macroscopic impacts

The speaker this week will be Dr. V. "Ram" Ramaswamy (pre-recorded).  The talk was originally presented in 2020 when Dr. Ramaswamy was awarded the 2020 AGU Jule Gregory Charney Lecture prize. 

Title: “Aerosols and their Gaming of the Climate System: Microscale presence to Macroscopic impacts."

Abstract:

Jule Charney was visionary extraordinaire in synthesizing theory, modeling, and observations to address key questions in the atmospheric and climate sciences. Recalling the Charney spirit in this lecture for one of the principal contemporary challenges, we focus on the role of atmospheric aerosols in the climate system. The manner in which aerosols have exerted their influence on the climate system stands in sharp contrast to other climate drivers e.g., well-mixed greenhouse gases. Natural and anthropogenic tropospheric aerosols, and stratospheric aerosols, span a diverse range in characteristics. Advances in theory, modeling and observations have led to major insights into aerosol effects on the atmospheric general circulation, and surface heat and moisture budgets, measured against unforced variability and other drivers. The perturbations in atmospheric aerosol composition, including the important interactions with clouds, alter the radiative balance, diabatic heating, temperature and precipitation. Causal understanding of climate trends over the past several decades indicates that anthropogenic tropospheric aerosols have counteracted greenhouse gas effects to a significant extent globally and regionally, traceable through the thermodynamic and dynamic responses. The understanding of 20th Century aerosol pollution and climate effects reveals the potential influences for the 21st century climate response to emissions scenarios, with ramifications for solar radiation management issues. The recent COVID-19-associated decrease in emissions offers another striking incidence of discernible aerosol perturbations. The climate perturbation by aerosols reminds us of an important Charney legacy (the 1979 National Research Council report). Charney's optimism and collegiality, together with his brilliance in forging the community's thinking on important questions, infuses enthusiasm even today in addressing the pressing climate challenges of our times.