Wednesday, 25 January 2012: 9:00 AM
A Calculation of Feedbacks Based on Climate Variations Over the Last Decade
Room 256 (New Orleans Convention Center )
I have calculated the strength of the temperature, water vapor, cloud, and albedo feedbacks in response to climate variations over the last decade. In general, the global average feedbacks agree well with those in comparable climate model runs. For the temperature and water vapor feedbacks, the average of the ensemble of climate models faithfully reproduces the spatial pattern of the feedbacks. The model ensemble average does a reasonable job simulating the spatial pattern of longwave and shortwave cloud feedbacks, but there are important differences in the net cloud feedback. The models predict a positive feedback in the tropics and a near-zero feedback in the northern hemisphere extratropics, while the observations show a negative feedback in the tropics and a strong positive feedback in the northern hemisphere extratropics. These disagreements tend to cancel in the global average, leading to better agreement there.