Tuesday, June 26, 2012

New paper finds greenhouse gas warming to be half of IPCC assumptions

A new paper published in the Journal of Atmospheric and Solar-Terrestrial Physics finds the sensitivity of Earth's climate to changes in greenhouse gases is about half that assumed by the IPCC. The paper examines changes in solar activity to determine 
"The sensitivity of the ECS [Earth's climate system] to changes in radiative forcing at the top of the atmosphere is equal to 0.41±0.05 K W−1 m2." 
The IPCC, however, claims that a change in the top of the atmosphere [TOA] radiation of 3.7 W/m2 from a doubling of CO2 will lead to a 3°C ± 1.5°C temperature increase. The IPCC climate sensitivity is therefore 3K/(3.7W/m2) or 0.81 K/W/m2, about double the amount [0.41 K/W/m2] determined by this new paper. 

Note, however, this paper calculates sensitivity on the basis of solar radiation, which is significantly different from infrared radiation from greenhouse gases. Unlike UV and visible radiation from the Sun, infrared radiation from greenhouse gases cannot heat the oceans [70% of Earth's surface area], therefore the sensitivity to greenhouse gases on the land surface is calculated to be 

(1-.70)*0.41 = 0.12 K/W/m2

indicating the effect of doubling CO2 levels on Earth's climate is trivial and confirming the low sensitivities obtained by others from observations without computer gaming. Here here here as well as Lindzen & Choi, Paltridge, Spencer & Braswell, and others.

Estimation of impulse response of Earth's climate system at short time intervals

  • Chair of Meteorology and Climatology, Saratov State University, Astrakhanskaya st. 83, 410012 Saratov, Russia
The method is described for restoration of the impulse response h(t) of the Earth's climate system (ECS), regarded as a time-invariant linear dynamical system whose input is the change in solar constant, and output - the global mean surface temperature anomalies. Search for solution of the ill-posed inverse problem is carried out on a compact set of convex downward non-negative functions. This suggests that ECS may be a first-order dynamic system or a set of similar independent subsystems with different time constants. Results of restoration of h(t) at time intervals up to 100 months show that it is a rapidly decreasing function, which do not differ from zero for t>3 months. An estimate of the equivalent time constant gives the average value of 1.04±0.17 months. The sensitivity of the ECS [Earth's climate system] to changes in radiative forcing at the top of the atmosphere is equal to 0.41±0.05 K W−1 m2.

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