Tuesday, August 2, 2011

Bray and von Storch on Tollefson's piece in nature

RE: ‘The Sceptic Meets His match' (Nature vol 475 28 July 2011: 440-441), Jeff Tollefson.

In the recent issue of nature (vol 475 28 July 2011), Jeff Tollefson reported about a pamphlet of the Heartland Institute from 2007.  Results from our 2003 survey among climate scientists were used for the statement  “The survey clearly shows that the debate over why climate is changing is still underway, with nearly half of the climate scientists disagreeing with what is often claimed to be a ‘consensus view’”. Tollefson goes on to accurately state that “In the survey, nearly 56% of climate scientists agreed that human activity is causing climate change, 14% were unsure and 30% disagreed”.  Tollefson also goes on to state that Bast [founder of the Heartland Institute] “dismisses the findings of a follow up survey by Bray and von Storch [this is our 2008 survey] which found that more than 85% of the responding scientists agreed that human activity is behind climate change.” - also an accurate interpretation of the survey data. Tollefson spoke to one of us (HvS), and we find his research done well.

The full surveys, from 1996, 2003 and 2007 are all available on-line (Bray, D., and H. von Storch, 2010: CliSci2008: A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change, GKSS Report 2010/9, and Bray, D. and H. von Storch, 2007: Climate Scientists’ Perceptions of Climate Change Science. GKSS-Report 11/2007).

The changing agreement over time among climate scientists about the existence of a warming (manifestation) and about the dominant cause (namely GHGs; "attribution") is displayed in this diagram, which is taken from the 2010-study by Dennis Bray (Bray, D.: The scientific consensus of climate change revisited. Environ. Sci. Policy (2010), doi:10.1016/j.envsci.2010.04.001)

Tollefson’s article talks about ‘dimensions’ of consensus as consensus is not as clear cut as often portrayed.  From our surveys we have learned that some ‘dimensions’ of ‘consensus’ have increased, others have decreased. In particular for the two key dimensions manifestation of climate change, that it is happening regardless of what is causing it, as well as attribution to human activities, consensus has increased among climate scientists since the beginning of our surveying.

What has recently decreased is the “legitimation” of the IPCC as representing this consensus, because in recent years an opposition has formed which asserts that the IPCC is underestimating the severity of the change (see Bray, 2010). From our own observations of discussions among climate scientists we also find hardly consensus on many other issues, ranging from changing hurricane statistics to the speed of melting Greenland and Antarctica, spreading of diseases and causing mass migration and wars.

We will continue surveying climate scientists about their view and opinions on climate change and climate policies.


Stan said...

I think it important to remember, that despite the woeful performance of expert opinion over the course of history, there remains at least a possibility that climate scientists might be correct in some part of these judgments.

Hans von Storch said...

what do you mean with "climate scientists might be correct" - do you mean all, most, some? Which judgments? - that it is getting warmer, that human are causing it, that sea level will rise by about 2 until the end of this century, that ice bears will die out, that climate wars will rage in future?

CS41y said...

What does woeful performance of expert opinions mean? Expert opinion in modern science has done very well. A common misconception is that something reported in the news or magazine is considered the prevailing view. Another misconception is the author of the article often doesn't properly describe an experiment or conclusion. Example, a biologist finds through tests that rats with white fur are more likely to get cancer from coffee under specific conditions. A journalist will often just report that coffee causes cancer. Or at least the headline will misleadingly state that. But the study was actually specific to who, what and how it happens. That's why it feels like one day research stages eggs are bad for you and then a new article is written in the news that people who eat eggs are healthier.

This is just an example (I don't know anything about biology and rat cancer). But I can still identify the issues because I have been trained through almost a decade of college to analyze an articles merit. So I'll show you how it might go.

The definition of "healthy" or "bad" isn't stated. So right away its left to the reader to imagine what it means. How many rats were tested. How much of something did the rats get tested. For instance many food supplements show an increased in cancer rates by consuming them. But it often is given to rats or mice in quantities so large you might never consume that much per kilogram of body mass as the mice did. These are just things as examples.

It is important to clarify that this "study" labelled anyone who answered their survey as being a climate scientist. Most of those who claim climatologists are wrong hold degrees in fields completely unrelated to science. Such as lawyer, Doctor, accountant, etc. I wouldn't argue they aren't intelligent people but they aren't experts in any science or even particularly credible to comment on scientific issues. It takes years of training to be able to properly conduct science. Without using vague definitions, faulty methodologies, faulty logical arguments, jump to conclusions based on evidence that isn't really related, get peer reviewed, and a whole host of issues related to statistical accuracies with a survey.