Climate Change Denial's so Hot Right Now...

...it's all over the blogs, the Herald, The New York Times, Manukau.

For the life of me I can't understand the burrowing ostrich mentality which prompts people to pump out disinformation hoping to forestall action on what is likely to be a very serious problem (and one which will affect us all - sceptics and credulous - alike).

A textbook example of the disingenuity that emits from the deniers camp is the recent open letter to Ban Ki-Moon from a self proclaimed group of climate experts. As always, the vast majority of the 'experts' are not climatologists. And, as always, what they write is misleading (to put it very mildly).

Let's look at one short extract:

z Recent observations of phenomena such as glacial retreats, sea-level rise and the migration of temperature-sensitive species are not evidence for abnormal climate change, for none of these changes has been shown to lie outside the bounds of known natural variability.

z The average rate of warming of 0.1 to 0. 2 degrees Celsius per decade recorded by satellites during the late 20th century falls within known natural rates of warming and cooling over the last 10,000 years.

z Leading scientists, including some senior IPCC representatives, acknowledge that today's computer models cannot predict climate. Consistent with this, and despite computer projections of temperature rises, there has been no net global warming since 1998. That the current temperature plateau follows a late 20th-century period of warming is consistent with the continuation today of natural multi-decadal or millennial climate cycling.

One at a time:

"Recent observations of phenomena such as glacial retreats, sea- level rise and the migration of temperature-sensitive species are not evidence for abnormal climate change, for none of these changes has been shown to lie outside the bounds of known natural variability."

Quite true! And quite besides the point, as none of the aforementioned observations are claimed as key evidence for Anthropogenic Global Warming (AGW) . They do, however, correspond with satellite and other instrumental measures of temperature warming and, as such, provide collaborating evidence - and they give us some idea of the consequences of AGW - but they aren't the key evidence. The crucial evidence for AGW is the rise in temperatures (observable in surface and satellite records) combined with the rise in Greenhouse Gases (GHGs). GHGs, which we know, thanks to Carbon Isotope measures, are human produced; and which we can expect, thanks to our understanding of basic atmospheric physics, to increase temperatures. Moreover, no known natural process, (such as solar radiation), which could otherwise be causing temperature increases is currently trending in a manner which is constant with observed temperatures. This is why the vast majority of climatologists believe that current global warming is human produced.

And while it is true that, current fluctuations in glaciation and the like, fall within the bounds of
'natural' variability, and while there is no reason to believe that AGW will lead to climate change greater than that experienced naturally by our planet in the past, this is no cause for complacency. Natural variability has seen temperatures so warm that crocodile-like creatures lived near the Poles. Do the 'scientists' who signed the letter really believe that humanity could endure the transition associated with such climate change and not experience significant costs in terms of human welfare.

The average rate of warming of 0.1 to 0. 2 degrees Celsius per decade recorded by satellites during the late 20th century falls within known natural rates of warming and cooling over the last 10,000 years.

Which may be true (I haven't double checked) but even so - so what? Once again: we know that we are increasing CO2 in the atmosphere, we know that - everything else being equal - more C02 will mean higher temperatures, and we know that temperatures are increasing in a manner that we can't attribute to any natural phenomenon. Why - given all this - would we need a faster rate of warming than ever observed before to provide us with proof of AGW?

Finally they state that "there has been no net global warming since 1998." Once again they are being disingenuous. 1998 was a particularly warm year thanks to El Nino. This is understood and explained and isn't a threat to computer models or climate predictions. What's more, if you actually run proper trend lines through the 1998 to present data there are still trends of warming. (Two very good posts explaining this are here and here).

God this gets tiresome.