text: August, 2007 RESEARCH UPDATE: Our peer-reviewed paper showing the natural cooling behavior of tropical cirrus clouds in response to warming was published on August 9 in Geophysical Research Letters. (The UAH news release is here. ) In that paper we describe satellite evidence for a natural cooling mechanism (negative feedback)that occurs when the tropical atmosphere heats up. This is in contrast to all leading climate models, which have cirrus clouds behaving as a positive feedback, amplifying warming tendencies.