How Feedbacks Amplify Global Warming
In a previous post (see that post for the cited literature), I calculated ECS from data provided in the Indicators of Global Climate Change for 2025. I made 4 calculations using two different baselines (1850-1900 and 1790-1839) and two different means for current temperature (the last 4 years and the last 12 years). I'd like to share again just one of these so I can illustrate how feedbacks amplify a warming signal. These are the values I used that was based on a ΔT = 1.23°C (the difference between 2013-2025 and 1850-1900). ΔT = 1.23°C (HadCRUT5) ΔF = 2.60 W/m² (IGCC25) EEI = 1.12 W/m² (IGCC25) ΔF2xCO ₂ = 3.93 W/m² (AR6) For the sake of brevity, I'm going to relabel the forcing for doubling CO2 that I had labeled ΔF2xCO ₂ as ΔFc. Using these values and the Energy Balance Equation, we can calculate ECS to be: λ = ΔT/(ΔF - EEI) λ = 1.23/(2.60-1.12) = 0.83°C/W/m² ECS = λ*ΔFc = 0.83*3.93 = 3.3°C To calculate ECS, we didn't have to know any of the feedbacks...