The news that 2005 was the warmest year ever recorded in Australia comes at the end of a year in which, to the extent that facts can settle anything, the debate over human-caused global warming has been settled. Worldwide, 2005 was equal (to within the margin of error of the stats) with 1998 as the warmest year in at least the past millennium.
More significantly, perhaps, 2005 saw the final nail hammered into the arguments climate change contrarians have been pushing for years. The few remaining legitimate sceptics, along with some of the smarter ideological contrarians, have looked at the evidence and conceded the reality of human-caused global warming.
Ten years or so ago, the divergence between satellite and ground-based measurements of temperature was a big problem – the ground based measurements showed warming in line with climate models but the satellites showed a cooling trend. The combination of new data and improved calibration has gradually resolved the discrepancy, in favour of the ground-based measurements and the climate models.
Another set of arguments concerned short-term climate cycles like El Nino. The late John Daly attributed the high temperatures of the late 1990s to the combination of El Nino and solar cycles, and predicted a big drop, bottoming out in 2005 and 2006. Obviously the reverse has happened. Despite the absence of the El Nino or solar effects that contributed to the 1998 record, the long-term warming trend has dominated.
Finally, there’s water vapour. The most credible of the contrarians, Richard Lindzen, has relied primarily on arguments that the feedback from water vapour, which plays a central role in climate models, might actually be zero or even negative. Recent evidence has run strongly against this claim. Lindzen’s related idea of an adaptive iris has been similarly unsuccessful.
Finally, the evidence has mounted up that, with a handful of exceptions, “sceptics” are not, as they claim, fearless seekers after scientific truth, but ideological partisans and paid advocates, presenting dishonest arguments for a predetermined party-line conclusion. Even three years ago, sites like Tech Central Station, and writers like Ross McKitrick were taken seriously by many. Now, anyone with access to Google can discover that they have no credibility. Chris Mooney’s Republican War on Science which I plan to review soon, gives chapter and verse and the whole network of thinktanks, politicians and tame scientists who have popularised GW contrarianism, Intelligent Design and so on.
A couple of thoughts on all this.
First, in the course of the debate, a lot of nasty things were said about the IPCC, including some by people who should have known better. Now that it’s clear that the IPCC has been pretty much spot-on in its assessment (and conservative in terms of its caution about reaching definite conclusions), it would be nice to see some apologies.
Second, now that the scientific phase of the debate is over, attention will move to the question of the costs and benefits of mitigation options. There are legitimate issues to be debated here. But having seen the disregard for truth exhibited by anti-environmental think tanks in the first phase of the debate, we shouldn’t give them a free pass in the second. Any analysis on this issue coming out of a think tank that has engaged in global warming contrarianism must be regarded as valueless unless its results have been reproduced independently, after taking account of possible data mining and cherry picking. That disqualifies virtually all the major right-wing think tanks, both here and in the US. Their performance on this and other scientific issues has been a disgrace.