Do “Brown Clouds” Have a Silver Lining?
In the paper, Ramanathan and Carmichael integrated observed data from satellites, aircraft, and surface instruments about the warming effect of black carbon and found that its forcing, or warming effect in the atmosphere, is about 0.9 watts per meter squared. That compares to estimates of between 0.2 watts per meter squared and 0.4 watts per meter squared that were agreed upon as a consensus estimate in a report released last year by the Intergovernmental Panel on Climate Change (IPCC), a U.N.-sponsored agency that periodically synthesizes the body of climate change research. Ramanathan and Carmichael said the conservative estimates are based on widely used computer model simulations that do not take into account the amplification of black carbon’s warming effect when mixed with other aerosols such as sulfates. The models also do not adequately represent the full range of altitudes at which the warming effect occurs. The most recent observations, in contrast, have found significant bla
