Muller: “I draw a distinction between skeptics and deniers”

  • 07 Nov 2011, 14:00
  • Verity Payne

The Berkeley Earth Surface Temperature (BEST) study has been the subject of an ongoing media saga over the last few weeks.

US physicist Richard Muller took allegations made by climate skeptics that climatologists had been manipulating the data and over-estimating global warming seriously. He assembled the BEST project - partially funded by the Koch brothers - to address those criticisms and reassess global temperature trends.

When the project's papers were released a few weeks ago however, it was revealed the study had found that global land temperatures have increased by around 1°C over the last 60 years - a finding in line with the temperature reconstructions from other groups of scientists. The study also found that the urban heat island effect and poor station quality - touted by skeptics as invalidating other research groups' temperature reconstructions - did not bias the results obtained from these earlier studies.

The skeptic response to the study ranged from swift backtracking - 'we've never doubted warming' - to an attack by the Mail on Sunday on Muller and the BEST study, which relied on a dubious analyis from a climate skeptic think-tank and misrepresented BEST co-author Judith Curry.

Muller and the BEST team have also received criticism from both scientists and skeptics for releasing the BEST data before peer review.

Now Muller has been interviewed by the journal Nature Climate Change. The interview provides little new information about a project that has already been extensively picked over by a variety of news outlets, but does give us some new insight into his views - particularly how he views the nature of climate skepticism.

Most revealing was Muller's response to the question "Do you think your results will convince sceptics that global warming is real?":

"I draw a distinction between sceptics and deniers. The sceptics are people I respect - they have raised legitimate issues and, from my experience, are open minded. The deniers are people who start with a conclusion and only pay attention to the data that support it. I do think that our results could change the minds of some sceptics about the reality of global warming."

He also says

"This field [climate science] has been more contentious than need be because some scientists have confused the sceptics with the deniers. Scientists were told that sceptics were anti-science; that this issue was akin to the one over intelligent design."

It would be interesting to know who exactly Muller is referring to here. It is undoubtedly true that prominent climate skeptics routinely rubbish the science of climate change (see for example here, here and here). This has included the skeptic blog Watts Up With That, who Muller was previously close to and who initially supported the BEST project.

A few amateur skeptics have raised legitimate (if minor) issues which have appeared in the peer-reviewed literature and then been included in the scientific process. And many others of course have been legitimately confused by a confusing public debate, with the resulting impact on 'belief' in climate science.  

Muller describes himself as "sceptical at the level that every scientist tries to be sceptical" and also says:

"Many scientists signed petitions supporting 'climate science' without ever looking at the legitimate issues raised by the sceptics. I feel that if you sign a petition and put your credentials after your name, then you should have examined the issues with your scientific expertise first, and not just joined a bandwagon of other scientists."

It is this kind of comment - with the inherent implication that the BEST project team are the first to look objectively at the data - which has somewhat irritated climate scientists who have been working in the area for years.

Muller still isn't convinced that the Intergovernmental Panel on Climate Change (IPCC) is right about the degree of human influence on global warming. He says:

"I have not done a scientific study, but my own impression - based on reading the literature - is that some of the warming we have seen is caused by humans. To my mind, you can't rule out half of the warming being caused by humans, but I think to conclude that most of it is - as the Intergovernmental Panel on Climate Change says - could be an overestimate. This is my personal impression; the other members of the team might feel differently."

In this view Muller is at odds with the weight of scientific evidence.

Carbon dioxide which comes from burning fossil fuels has a distinct manmade signal (explained further here) - and the proportion of carbon dioxide in the atmosphere that has this "human fingerprint" is rising. Skeptics frequently cite solar activity or other natural climate variation to explain the warming trend. All of these natural elements have been thoroughly investigated by climate scientists, and have been ruled out as the dominant cause of warming.

These fundamental principals, added to the fact that there are no plausible competing theories to explain the observed warming trend, have convinced 97% of active climate scientists that humans are a significant contributing factor to global warming.

Muller also explains the slight discrepancy between the temperature records of from NASA and Hadley Centre data:

"We've already received feedback from NASA, and we've resolved the difference with them. It turns out that they had included some stations over water that we omitted; when they omit them too the difference vanishes. The disagreement with Hadley is of statistical interest only, because we have such small error uncertainties. The Hadley Centre temperature change is an outlier. It is smaller by a couple of tenths of a degree."

Overall, however, the interview is probably more interesting for what it says about Muller than what it says about climate science.


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