Abstract
Theory and computational modeling indicate that forcings by natural and human-influenced activities over the past century have significantly perturbed the Earth’s atmosphere and surface energy balance. The natural (solar irradiance, volcanic aerosols) and anthropogenic (well-mixed and short-lived greenhouse gases, tropospheric aerosols, land-use) factors have altered atmospheric composition and forced changes in the surface and atmospheric heating. This has resulted in perturbations to the thermodynamic budget, large-scale atmospheric dynamics, and global-to-regional temperature and precipitation. How the forcings have impacted the climate system over the 20th century is investigated utilizing state-of-the-art climate models (e.g., IPCC AR6 class). Continuous satellite observations of the Earth’s radiation budget over the past two decades provide stark evidence of the roles of different factors in increasing the Earth’s Energy Imbalance and the heating of the planet. This has implications for both temperature and hydrologic extremes, and poses challenges for the human ecosystem in terms of heat waves and water availability (too much or too less). The understanding of the 20th century forcings and response becomes crucial to the projections of the 21st century climate from the seasonal to the multidecadal timescales, including the frequency and severity of extremes.
Bio
Venkatachalam (“Ram”) Ramaswamy is Director of NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL) and a member of the Atmospheric and Oceanic Sciences Program Faculty at Princeton University. Ram holds a Ph. D. in Atmospheric Sciences from the State University of New York at Albany, Albany (NY). He was a Fellow in the Advanced Study Program at the National Center for Atmospheric Research, Boulder (CO) before joining GFDL and Princeton. His principal interests are understanding and prediction of the Earth System, quantifying the natural and anthropogenic forcings, climate feedbacks and responses using numerical models and observations. At NOAA/GFDL, the fundamental physical understanding is utilized to provide information, data, and products, including the prediction and projection of global-to-regional climate variability and change and impacts on ecosystems. Applications with NOAA/ GFDL models scope a wide range of climate extremes of societal and policy concerns spanning weather-to-centennial timescales e.g., hurricanes, storms, droughts, floods, snowpack, ice and glacier melt, ocean heat uptake, sea-level rise, heat waves, land and living marine ecosystems.
Ram has served on the Intergovernmental Panel on Climate Change (IPCC) Working Group I scientific assessments (1992-2021) and Joint Scientific Committee of the World Climate Research Program (2003-2010). He is an author or co-author of over 190 peer-reviewed papers. He was: Co-chair of the Panel on Climate Variability and Change, National Research Council (2017) Decadal Survey for Earth Science and Applications from Space; Co-author, International Committee on Space Research (COSPAR) Roadmap for 2016-2025 on “Observation and integrated Earth-system science”; and Member, Working Group 4, “A Predictive Ocean”, UN Oceans Decade (Arctic Region) (2020-2021). He is currently serving on the WMO Executive Council Panel on Polar and High Mountain Observations, Research, and Services.
Ram is a Fellow of the American Meteorological Society (AMS), American Geophysical Union (AGU), American Association for the Advancement of Science, and American Physical Society. He is a recipient of the: AMS Houghton award, Roberts Lectureship, Rossby medal; AGU Charney Lectureship; US Distinguished Executive Presidential Rank award, and three-time WMO Norbert Gerbier MUMM International awardee. He was a member of the IPCC team that was co-recipient of the 2007 Nobel Peace Prize.
Director of NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL)