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FEEDBACK PARAMETERS. Let T s = global mean surface air temperature R= net flux of heat into the climate system Δ R f = change in R due to some change in the forcing, e.g., a doubling of CO 2 Δ T s = equilibrium change in T s due to Δ R f .
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FEEDBACK PARAMETERS Let Ts= global mean surface air temperature R= net flux of heat into the climate system ΔRf = change in R due to some change in the forcing, e.g., a doubling of CO2 ΔTs = equilibrium change in Ts due toΔRf
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, λ = - 3.3 W/m2/K) • Water Vapor Feedback (positive, λ = 1 to 1.5 W/m2/K) • Ice/Snow Albedo Feedback (positive, λ = 0.1 to 0.5 W/m2/K) • Cloud Feedback (λ = ?)
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 2°C to 4.5°C, with a most likely value of about 3°C. IPCC 4AR Chapter 10