by Norm Buske
Although I am a long-time, casual skeptic of global warming, I agree that evidence of severe, largely anthropogenic warming of the Northern Thermal Hemisphere (NTH) is compelling. The warming of the NTH explains progressive loss of Arctic sea ice.
Meanwhile, the average temperature of the planet surface has evidently stabilized for the last dozen years or so:
(Thick line is simple 3-year running average. Average of 1979-88 decade is set to zero.)
Therefore, global warming has evidently ceased, at least for now, because the Southern Thermal Hemisphere (STH) has entered a cooling phase, compensating for the anthropogenic warming of the NTH.
After an artifactual step change (in December 1991) in the NSIDC satellite record of the extent of Antarctic sea ice has been removed from the data, a recent increase in the extent Antarctic sea ice is evident:
(Red curve is LOWESS smooth.)
William of Ockham might explain this increase of Antarctic sea ice extent as an effect of the STH having cooled, just as the loss of Arctic sea ice has been explained as an effect of the NTH having warmed.
Anthropogenic sources (of warming) are concentrated in the NTH, with fewer sources in the STH. So there is a prospect that the recent cooling of the STH is not anthropogenic. Or the thermal hemispheres might be coupled such that the warming of the NTH is becoming compensated by cooling of the STH.
–Here is a challenge for proponents of global warming: Show how anthropogenic warming of the NTH leads to cooling of the STH, or else allow that the cooling of the STH is practically independent.