Climate Models Underestimate Dynamic Cloud Feedbacks in the Tropics

Do Climate Models Underestimate the Sensitivity of Northern Hemisphere

The sensitivity of Northern Hemisphere sea ice cover to global temperature change is examined in a group of climate models and in the satellite-era observations. The models are found to have well-defined, distinguishable sensitivities in climate change experiments. The satellite-era observations show a larger sensitivity— a larger decline per degree of warming—than any of the models. To evaluat...

Tropical Water Vapor and Cloud Feedbacks in Climate Models: A Further Assessment Using Coupled Simulations

By comparing the response of clouds and water vapor to ENSO forcing in nature with that in Atmospheric Model Intercomparison Project (AMIP) simulations by some leading climate models, an earlier evaluation of tropical cloud and water vapor feedbacks has revealed the following two common biases in the models: 1) an underestimate of the strength of the negative cloud albedo feedback and 2) an ove...

Low cloud-SST feedbacks influence tropical Pacific climate variability

Standard climate models radiation codes underestimate black carbon radiative forcing

Radiative forcing (RF) of black carbon (BC) in the atmosphere is estimated using radiative transfer codes of various complexities. Here we show that the two-stream radiative transfer codes used most in climate models give too strong forward scattering, leading to enhanced absorption at the surface and too weak absorption by BC in the atmosphere. Such calculations are found to underestimate the ...

The complexity of Atmospheric and Climate Models: Assumptions and Feedbacks

While it is true that the physical principles and equations discussed in part one do form the “core” of any atmospheric or climate model, there are processes in the observed system that are difficult to represent due to our incomplete understanding of the process, or the fact that some processes are not exact. Many of these processes are what we call “feedbacks”. Feedbacks are manifestations of...