A Short Summary of Soon, Connolly and Connolly, 2015; “Re-evaluating the role of solar variability on Northern Hemisphere temperature trends since the 19th Century”

By Andy May

Soon, Connolly and Connolly (2015) is an excellent paper (pay walled, for the authors preprint, go here) that casts some doubt about two critical IPCC AR5 statements, quoted below:

The IPCC, 2013 report page 16:

“Equilibrium climate sensitivity is likely in the range 1.5°C to 4.5°C (high confidence), extremely unlikely less than 1°C (high confidence), and very unlikely greater than 6°C (medium confidence).”

Page 17:

“It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”

Soon, Connolly and Connolly (“SCC15”) make a very good case that the ECS (equilibrium climate sensitivity) to a doubling of CO2 is less than 0.44°C. In addition, their estimate of the climate sensitivity to variations in total solar irradiance (TSI) is higher than that estimated by the IPCC. Thus, using their estimates, anthropogenic greenhouse gases are not the dominant driver of climate.

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