Friday, October 23, 2009

Irony on Realclimate

In their really aggressive attack on all human-induced climate change sceptics, they often resort to stupid ad hominems that show their disrespect for open discussion. I am sorry realclimate folks, but that was a no go. And then we have this other piece with some really nice irony.

Now, I could ask why anyone was still interested in a Mannian Reconstruction, since it was declared dead by several panels up to now, but hey, that'd be unfair. So, let's just consider the rest of the post. Where they discuss their scepticism of galactic rays as a major influence on Earth climate.

Point I: When I asked Svensmark why he presented a curve describing low cloud-cover from the ISCCP – used for correlation study with GCR (link) – that differed from the curves presented at the ISCCP web site (link), he informed me that he used a corrected version that has been published. Nevertheless, the ‘correction’ of the curve is controversial, and the ISCCP team is clearly not convinced, despite the likelihood of instrumental degradation.

Good practice would then be to present all the curves that cannot be ruled out because of errors. When asked why he didn’t present the other cures too, he said that he only wanted to show the one curve. Not a very convincing answer, and not very reassuring.

The funny thing about point 1 is that it is almost the same argument sceptics of Mann's Reconstruction further all the time. That he is cherry-picking a "corrected" version of the graph and thus doesn't show all the curves to select the most appropriate of them. Sadly, I am sure that the authors of this piece didn't see the irony when they wrote it.

Point II involves a ‘remarkable’ correlation, meant to demonstrate a link between high GCR flux and cold conditions. This analysis is based on a comparison between band-pass filtered ice-rafted debris from iceberg drifts (Bond, 2001) and Carbon-14 (a cosmogenic isotope) over the last 12,000 years (e.g. after the most recent ice age).

The relationship between temperature and drifting icebergs, however, is complicated and not so straight forward. Icebergs are formed when chunks of ice break off glaciers and icesheets – a process known as ‘calving’.

As is the relationship between Tree-Rings and Temperature, but that would be self-criticism so I don't expect it from them. I don't even think they saw the irony in this second point, too. Now, for the subject of galactic rays, I'm also not convinced about their actual influence on earth climate. But I am not denying that there is a possibility, that they have some influence. The question is whether it is neglectible or not.

All that said, I found it pretty shallow of them to accuse a different theory of things you yourself are not quite free of.

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