Special Geophysics Seminar: Deforestation Reshapes the Amazon Radiation Budget

Zoom: 

Abstract:

Land cover change is a perturbation that propagates from the surface to the top-of-atmosphere, where the Earth’s energy balance is set, and any imbalance drives climate change. In this talk, I will explore the coupled surface-atmosphere response over the Amazon, one of the planet’s largest land-cover change hotspots, using a hierarchy of satellite observations, each capturing the physics at its operating scale. I will show that in the Amazon, the all-sky biophysical response, surface and atmosphere combined, drives a top-of-atmosphere cooling, through a surface brightening and additional cloud reflectivity that roughly doubles it. This land-cover perturbation is unfolding alongside a shifting climate: the Amazon is darkening over the satellite era, driven by a decline in clouds across the southern Amazon. While both intact forest and deforested landscapes are darkening, deforested areas darken more slowly. This differential darkening exerts a buffering effect that grows with the fraction of forest cleared, through the surface brightening and the relative preservation of clouds over cleared land. By resolving the shortwave trend at the scale of the land-cover mosaic, I isolate a land-driven control that coarser analyses average out and set up a framework to ask the same question across other land-cover change drivers and climatic regimes.

Event Organizer: Dr. Leah Langer