In the first of six symposia planned at MIT this academic year on the subject of climate change, panels of specialists on the science of global climate described the state of knowledge on the subject today. They also discussed the areas where more research is needed to pin down exactly how severely and quickly climate change’s effects may occur, and what kinds of actions are urgently needed to address the enormous disruptions climate change will bring.

Keynote speaker Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry, gave an overview of the state of climate science today, explaining that the vastness of the timescales involved “is one of the things that makes this problem so fascinating.” However, she added, it also presents a real challenge in communicating the urgency of the issue, because carbon dioxide emissions being produced now can persist in the air for centuries, with their effects building over time.

Even if the world were to stabilize greenhouse gas emissions at today’s level, the temperature would continue to rise, and sea level would continue to rise even more, she said. Anywhere from 50 to 100 percent of the expected temperature increase from a given amount of carbon dioxide “is in the pipeline,” she said, because it takes time for the changed atmosphere and oceans to reach a new state of equilibrium: “The temperature stabilizes after a few hundred years, but the sea level just keeps going and going.”

She said “it’s sobering to take a look at the 25 warmest years that have been recorded, and realize that if you’re 32, you’ve been alive for all of them. We, this generation of people, are living on the warmest planet that has ever been measured in the environmental record.” And that increase is something we’re stuck with, she said. “Even if we go cold turkey” and eliminate all greenhouse gas emissions, “temperatures go almost constant for 1,000 years. The cumulative carbon dioxide that’s been emitted is what controls it.”

The symposium, which drew a capacity crowd to MIT’s Kresge Auditorium, was chaired by Kerry Emanuel, the Cecil and Ida Green Professor of Atmospheric Science, and featured two panels of leading climate scientists who described the state of present knowledge about the effects and extent of climate change, remaining uncertainties and how to address them, and how the physical effects of warming may vary under different policy approaches.

(Image: Jake Belcher)