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New Paper: Climate Models Underestimate Cooling From Clouds

A recent paper published in the Journal of Climate finds that climate models grossly underestimate cooling of the Earth’s surface due to clouds. According to the authors, “Coupled model intercomparison project (CMIP3) simulations of the climate of the 20th century show 40±20 W m−2 too little net cloud radiative cooling at the surface. Simulated clouds have correct radiative forcing when present, but models have ~50% too few clouds.

By way of comparison, the 40 W m-2 underestimate of cooling from clouds is more than 10 times the alleged warming from a doubling of CO2 concentrations [3.7 W m-2].

As Dr. Roy Spencer points out in his book,

The most obvious way for warming to be caused naturally is for small, natural fluctuations in the circulation patterns of the atmosphere and ocean to result in a 1% or 2% decrease in global cloud cover. Clouds are the Earth’s sunshade, and if cloud cover changes for any reason, you have global warming — or global cooling.”

This paper and a host of others demonstrate that many of the key assumptions in climate models  have been falsified by observations, therefore, the model predictions are also false.

Journal of Climate 2012 ; e-View

Observations of stratocumulus clouds and their effect on the eastern Pacific surface heat budget along 20°S

Simon P. de Szoeke, Sandra Yuter, David Mechem, Chris W. Fairall, Casey Burleyson, and Paquita Zuidema


 

Abstract

 

Widespread stratocumulus clouds were observed on 9 transects from 7 research cruises to the southeastern tropical Pacific Ocean along 20°S, 75°-85°W in October-November 2001-2008. The nine transects sample a unique combination of synoptic and interannual variability affecting the clouds; their ensemble diagnoses longitude-vertical sections of the atmosphere, diurnal cycles of cloud properties and drizzle statistics, and the effect of stratocumulus clouds on surface radiation. Mean cloud fraction was 0.88 and 67% of 10-minute overhead cloud fraction observations were overcast. Clouds cleared in the afternoon (15 h local) to a minimum of fraction of 0.7. Precipitation radar found strong drizzle with reflectivity above 40 dBZ.
Cloud base heights rise with longitude from 1.0 km at 75°W to 1.2 km at 85°W in the mean, but the slope varies from cruise to cruise. Cloud base-lifting condensation level (CB-LCL) displacement, a measure of decoupling, increases westward. At night CB-LCL is 0-200 m, and increases 400 m from dawn to 16 h local time, before collapsing in the evening.

Despite zonal gradients in boundary layer and cloud vertical structure, surface radiation and cloud radiative forcing are relatively uniform in longitude. When present, clouds reduce solar radiation by 160 W m−2 and radiate 70 W m−2 more downward longwave radiation than clear skies. Coupled model intercomparison project (CMIP3) simulations of the climate of the 20th century show 40±20 W m−2 too little net cloud radiative cooling at the surface. Simulated clouds have correct radiative forcing when present, but models have ~50% too few clouds.