A Determination of the Cloud Feedback from Climate Variations over the Past Decade

Abstract

Positive Message: Climate warming affects both cloud number and cloud properties, which in turn affect warming itself, creating a cloud-climate feedback that complicates predictions of the amount of warming caused by increasing concentrations of atmospheric carbon dioxide. This feedback has generally been considered to be positive, but so far we have only a qualitative idea of the effect. Dessler (p. 1523 ; see the news story by Kerr ) estimated the magnitude of the feedback by analyzing 10 years of satellite data on the flux of radiation through the top of the atmosphere. As expected, the feedback is positive and within the canonical range of estimates of how much warming will occur for a doubling of atmospheric CO ₂ : 2°C to 4.5°C.