Student Profile - MIT Joint Program on the Science and Policy of Global Change

A new student profile featuring my research as part of MIT's Joint Program on the Science and Policy of Global Change was recently published online and in print as part of the program's Summer 2016 newsletter, "Global Changes."

EAPS PhD student Daniel Rothenberg targets one of climate modeling’s biggest unknowns

Air pollution from power plants, internal combustion engines and other artificial sources impacts not only human health but also the global climate. The more particles we emit into the atmosphere, the more water droplets are likely to form around those particles inside clouds. Clouds with more droplets are thicker and brighter, so they reflect more solar radiation, thereby cooling the climate system in a process called the aerosol indirect effect. While much is known about the physics of how aerosols impact cloud formation, it’s hard to measure just how big a role the indirect effect plays in offsetting global warming. Today’s estimates of the magnitude of the indirect effect are highly uncertain; it may well have masked as much as 80 percent of warming during the 20th century due to carbon dioxide (CO2) emissions alone.

Reducing that uncertainty will become critical throughout the 21st century as more and more countries significantly reduce their greenhouse gas emissions in pursuit of the Paris Agreement’s goal of capping the rise in global mean surface temperature since preindustrial times at 2 degrees Celsius. Any major cut in airborne particulates will reduce the indirect cooling effect considerably, resulting in additional warming that climate models will need to estimate as precisely as possible.

To help meet this challenge, Daniel Rothenberg, a Joint Program PhD student in the Department of Earth, Atmospheric and Planetary Sciences, has spent the past two years developing concepts and software aimed at reducing the uncertainty in the magnitude of the indirect effect.

“If the sensitivity of the indirect effect is strong, then you might expect a much stronger warming associated with aerosol reduction in the future, and that makes the 2°C goal even more difficult to achieve,” says Rothenberg. “That our current models haven’t been able to reduce the uncertainty is a specter hanging over the climate community’s head, so it’s important to determine how strong these effects might be.” ...

Check out the rest of the interview here!