“Antarctic Ice Cores: The Sample Rate Problem“. Geologist David Middleton returns to tell us that those Antarctic ice cores that seem to support the climatology conspiracy consensus can’t be trusted. After-all, the ice doesn’t permanently capture the CO2 level at the exact instant it begins to form. Also, maybe CO2 got sucked out of the old ice. And everyone knows that only second-by-second CO2 samples can be trusted.

Actually, David is suggesting that the ice CO2 levels blend a bit. He wants us to think that maybe there have been large fluctuations in atmospheric CO2 that have been blurred together and are no longer seen in the ice samples, maybe the modern CO2 trend just happens to be an ordinary large natural swing in CO2, and that we just happen to be at the peak of one of those “swings”.

Although, if the ice cores chanced to suit denialist wishes I’m sure they’d be just fine. In this case the erratic plant leaf stomata CO2 proxy values (sotto voce: does David know that they are a computer model?) are praised because they show large fluctuations that can be used to “prove” that there has been wide variation in the modern era and hence today’s CO2 levels are perfectly natural.

This puzzling quote comes from one of the apparently supporting papers, CO2 diffusion in polar ice: observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core (italics mine):

“Smoothing of the CO2 record by diffusion is one to two orders of magnitude smaller than the smoothing by diffusion in the firn at the depth of 287m (gas age = 2.74 kyr BP) in the Siple Dome ice, and so does not degrade the record.”

So… scientists know about this crazy diffusion thing and have been able to assess it as being insignificant. So what’s David really trying to do?