Global Warming - Martin Weitzman Professor Of Economics, Harvard

PBS: The Odds of Disaster: An Economist's Warning on Global Warming

Most people do not realize how difficult it is to stabilize CO2 concentrations. It is not nearly enough to stabilize CO2 emissions, which would cause CO2 concentrations to keep on increasing at the same rate as before. (This is because changes in concentrations are proportional to emissions.) The problem is that if you want to stabilize CO2 concentrations, you have to make drastic cuts in CO2 emissions. This is no easy feat. Yet, unless it is done, we are liable to reach very high levels of CO2 concentrations.