,FEEDBACK PARAMETERS,Let Ts= global mean surface air temperature R= net flux of heat into the climate system Rf = change in R due to some change in the forcing, e.g., a doubling of CO2 Ts = equilibrium change in Ts due to Rf,Define Feedback parameters:,assuming the structure of the climate system is fixed due to changes in the structure i = 1, 2, 3, If the perturbation is small then,FEEDBACKS AFFECTING CLIMATE SENSITIVITY,Stefan-Boltzmann Law (negative, = - 3.3 W/m2/K) Water Vapor Feedback (positive, = 1 to 1.5 W/m2/K) Ice/Snow Albedo Feedback (positive, = 0.1 to 0.5 W/m2/K) Cloud Feedback ( = ?),The equilibrium global mean SAT warming for a doubling of atmospheric carbon dioxide (CO2), or equilibrium climate sensitivity, is likely to lie in the range 2C to 4.5C, with a most likely value of about 3C. IPCC 4AR Chapter 10,