A recent study in Nature magazine by a team of 17 scientists has reconstructed summer and winter temperature histories for West Antarctica. Yes, the place that’s typically around minus 30C so it’s in imminent danger of melting away, according to the alarmists. But if it were going to melt away, it would have done so a long time ago because, as the authors conclude: “Summer temperatures in West Antarctica increased through the early-to-mid-Holocene, reached a peak 4,100 years ago and then decreased to the present.” Hmmm. Warming thousands of years ago due to natural causes, then cooling down to the present. Turns out the climate is capable of varying all by itself. And if the poles are heating faster than average, someone forgot to tell the South Pole.

The authors claim in this study that they were able to use deep ice cores from Antarctica and apply a new method of analysis to identify separate summer and winter climate conditions. And one interesting subsidiary finding is that some patterns only showed up in one season or another, prompting them to caution that other studies may miss important climate variations because they only deal in annual averages.

The main discovery is that summer temperatures trended up from the end of the last glaciation to between 5,000 and 1,500 years ago, then have been going down since. Winter temperatures showed less variation generally, but did exhibit large fluctuations 8,000 to 10,000 years ago which did not have an obvious cause. Almost as though climate were inherently prone to instability and short-run changes that should not be over-interpreted even if you’re living through one.

In case you think the computer models have it all figured out, the study also includes these two charts that overlay the reconstructed summer and winter temperatures with climate model runs that tried to recreate them:

The upshot is that the models were somewhat successful on the summer series and not very successfully in the winter series. The authors argue that the variations in temperature are attributable to changing solar insolation as the Earth’s orbit varies, as well as to changing patterns of heat transport in the atmosphere. Though the last one is said with a “probably” in front of it, as in, it’s hard to say.

Still, we know what didn’t cause the warming in the distant past. That would be CO2.