Atmosphere Ocean Science Colloquium

Are Volcanic Impacts on Global Climate Overblown?

Speaker: Dr. Zachary McGraw, Postdoc at Columbia University

Location: Warren Weaver Hall 1302

Date: Wednesday, April 3, 2024, 3:30 p.m.


Volcanic eruptions form sunlight-blocking aerosols that can alter climate for up to several years. By reducing temperatures and reducing rain rates far from eruption sites, volcanic aerosols have been credited with perpetuating numerous historical events and even bringing humanity to near-extinction. This talk will reevaluate the temperature and precipitation changes in the global climate models used to substantiate these theories of dire volcanic impacts. With a wide range of arguments – drawing from aerosol dynamics, radiative transfer, energy conservation, and statistics – it will be demonstrated that climate models are in fact compatible with there being no firm evidence of global post-eruption catastrophe. It will be shown that volcanic cooling is most likely incapable of exceeding 1.5°C no matter how large an eruption is, while global precipitation responses – which we explain here for the first time – are at nearly all locations incapable of generating anomalous conditions. Lastly, this talk weighs in on how poor communication of eruption impacts stifles discussions of geoengineering and greenhouse gas impacts.