UN climate change expert reveals bias in global warming report

By Richard Tol
 

Three of the four installments of the Fifth Assessment Report (AR5) of the United Nations’ Intergovernmental Panel on Climate Change (IPCC), which claims to show the state of the global climate system under stress, are now available. 
All three show things are seriously amiss – although not necessarily with the climate itself. The final installment, to be published in September will further underline the need to reform the IPCC.
The IPCC has three working groups, each producing its own report. Working Group I, focusing on climate change itself, released its findings last September. Compared to the previous report, of 2007, it quietly revised downwards its estimate of eventual global warming. 

The first rule of climate policy should be: do no harm to economic growth. But the IPCC was asked to focus on the risks of climate change alone, and those who volunteered to be its authors eagerly obliged.

The IPCC became less pessimistic about climate change, although its press release would not tell you so. 
The report also illustrates just how outmoded the IPCC has become since it was founded in 1988. Its reports are written over a period of three years, and finished months before publication.
When preparations started on AR5, the world hadn’t warmed for 13 years. That is a bit odd, if you believe the models, but not odd enough to merit a lot of attention. 
By the time the report was finished, however, it hadn’t warmed for 17 years. That is decidedly odd, but hard to accommodate in a near-final draft that has been through three rounds of review. 
After the report was finalized, but before it was published, a number of papers appeared with hypotheses about the pause in warming. AR5 was out of date before it was released. 
The IPCC model – every six years a big splash of climate analysis – is broken.
Working Group 2, published in March, and focusing on the impacts of climate change, had a different problem. It lies at the heart of the previous IPCC controversy. The scientific literature now acknowledges that many of the more worrying impacts of climate change are in fact symptoms of social mismanagement and underdevelopment. 
The first rule of climate policy should be: do no harm to economic growth. But the IPCC was asked to focus on the risks of climate change alone, and those who volunteered to be its authors eagerly obliged. There is even a groundbreaking section on emerging risks. 
The first paper on an issue is always dramatic. That is the only way to get something onto the scientific agenda. Follow-up papers then pooh-pooh the initial drama. But the IPCC chose not to wait for those follow-up papers.
IPCC reports are often two to three thousand pages long, but there are two or three main findings only. 
Authors who want to see their long hours of IPCC work recognized should thus present their impact as worse than the next one. 
It was this inbuilt alarmism that made me step down from the team that drafted the Summary for Policy Makers of Working Group 2. And indeed, the report was greeted by the four horsemen of the apocalypse: famine, pestilence, war, death all made headlines.
April’s Working Group 3 had yet another problem. Its focus, climate policy, is a hot political debate in many countries. 
The Summary for Policy Makers is drafted by academics, but approved line-by-line by government representatives. Every clause that could possibly be used against a government position, either in a domestic debate or in international negotiations, was neutered or removed.
But the authors are at fault, too. A little bit of emission reduction costs little. But as targets get more stringent, costs escalate. Not so according to the IPCC: Very ambitious targets are said to be only slightly more expensive than less ambitious targets. 
This surprising finding is a statistical fluke. Emission reduction is easy according to some studies, which duly explore very ambitious targets. 
Emission reduction is hard according to other studies; very ambitious targets are prohibitively expensive and results not reported. 
The surprisingly low cost of meeting very stringent emission reduction targets is the result of selection bias. 
Oddly, the IPCC made the same mistake in the previous report.
The final part of the AR5 report, the Synthesis, will be published in September. It will fail to offer policy makers what they need to know: a systematic comparison of the costs of climate policy to its benefits, the avoided impacts of climate change. 
Compared to the most famous cost-benefit analysis of them all, the Stern Review, published in 2006, the IPCC finds that the impacts of climate change are lower and the impacts of climate policy higher. But the IPCC will not suggest that the emission reduction targets recommended by Stern – global emissions 25 percent below 2005 levels by 2050; stabilize warming at 2-3˚C – are, perhaps, too stringent.
Given its flaws, should the IPCC be disbanded? That would be pointless. Climate change is a problem of the future. Climate policy responds to forecasts of the future rather than measurements of the past. 
There are large climate bureaucracies around the world, who exist by virtue of climate science. If you abolish the IPCC, the climatocracy will create a new IPCC. The IPCC should therefore be reformed. 
Here are some suggestions: 
Away with the infrequent, massive set pieces. Away with alarmism – that has been tried for 25 years, with no discernible impact on emissions. Away with activists posing as scientists. Away with the freshman mistakes. 
Just good, sober, solid science. Let the chips fall where they may.
Richard Tol is a professor of economics at the University of Sussex and the Vrije Universiteit Amsterdam. He has been involved in the IPCC since 1994.


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