News, Studies and Resources 28 Apr, 2021
Clouds and Global Warming
By Andy May
This post is inspired by an old post on the CERES cloud data by Willis Eschenbach that I’ve read and re-read a lot, “Estimating Cloud Feedback Using CERES Data.” The reason for my interest is I had trouble understanding it, but it looked fascinating because Willis was comparing CERES measured cloud data to IPCC modeled cloud feedback. I love obscure, back-alley comparisons of models and data. They tend to show model weakness. I learned this as a petrophysical modeler.
Willis wrote the post as a response to a paper by Paulo Ceppi and colleagues on cloud feedback in global climate models (Ceppi, Brient, Zelinka, & Hartmann, 2017). We’ll refer to the paper as Ceppi17. I took the time the last few days to understand Willis’ post and Ceppi’s paper and this is what I figured out, let me know what you think in the comments.
In Ceppi17, N = F + λΔT. N is the energy flux imbalance at the top of the atmosphere, F is a forcing, in W/m2 due to a sudden increase in greenhouse gases. The hypothetical situation used in the paper was a quadrupling of the CO2 instantly, relative to preindustrial conditions. Then they calculated a hypothetical F. “λ” is the cloud feedback and ΔT is the total global temperature change required to regain equilibrium, or an N of zero. Their feedback numbers cannot be duplicated with data due to the implausible scenario. Here are two more versions of the equation for reference.
https://co2coalition.org/2021/04/28/clouds-and-global-warming/
