The Hockey Schtick brings this to our attention. It seems Dr. Roy Spencer was prescient with his observation:
“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.”
Readers might also recall that evidence has been found for Spencer’s 1-2% cloud fluctuation. Even the National Science Foundation recognizes the role of clouds is uncertain: NSF Releases Online, Multimedia Package Titled, “Clouds: The Wild Card of Climate Change”
WUWT readers may recall the recent paper by Suckling and Smith covered at WUWT: New paper: climate models short on ‘physics required for realistic simulation of the Earth system’
In the Suckling and Smith paper it was concluded that the models they reviewed just don’t have the physical processes of the dynamic and complex Earth captured yet. This paper by de Szoeke et al. published in the Journal of Climate finds that climate models grossly underestimate cooling of the Earth’s surface due to clouds by approximately 50%
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.“
Let that 40 watts/ square meter sink in a moment.
The 40 watts/ square meter underestimate of cooling from clouds is more than 10 times the alleged warming from a doubling of CO2 concentrations, which is said to be 3.7 watts/square meter according to the IPCC (AR4 Section 2.3.1)
So the cloud error in models is an order of magnitude greater than the forcing effect of Co2 claimed by the IPCC. That’s no small potatoes. The de Szoeke et al. paper also speaks to what Willis Eschenbach has been saying about clouds in the tropics.
Here is the paper:
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.
Given this order of magnitude blunder on clouds, it seems like an opportune time to plug Dr. Spencer’s book where he pointed out the 1-2% cloud forcing issue. Click to review and/or buy at Amazon.