Tuesday 20 October 2009

The BBC should report climate change facts rather than political spin

Science reporting that downplays sober science in favour of the shrill shriek of climate denialists is nothing but propaganda
A controversy has erupted over a recent blog post by Paul Hudson that turned into a news story on BBC online with the title "What happened to global warming?" Does it mark an "amazing U-turn" of the BBC on climate, or was this a legitimate piece of reporting as the BBC maintains?
Perhaps my view as a climate scientist is of interest. To put it upfront: I think Hudson's article is more political spin than news reporting.
The piece starts with a bold assertion: "For the last decade we have not observed any increase in global temperatures." To be correct, this should have read: "If we cherry-pick a particular data set which excludes the part of the globe that warmed most, and also cherry-pick a time interval that starts with the warmest year of the 20th century and ends with the coldest year of the 21st, then we just manage to find a nearly flat piece of temperature curve."
We discussed the details of all this recently on RealClimate. The bottom line: Hudson referred to temperature data of the British Met Office that show a smaller warming recently because they leave out the Arctic, which is where most recent warming has occurred (as the Met Office confirms in its own study, (Simmons et al. 2009). And he cleverly compared 1998 (a year that stands out well above the climate trend due to an El Niño event in the Pacific) to 2008, a year that happens to be below the climate trend line, again due to natural variability. But note that in the global Nasa temperature data, even the cherry-picked trend over 1998-2008 is warming.
Hudson claims that the data contradicts climate models – which would be untrue even if temperatures had in fact stagnated. The models and data both show that due to natural variability, warming is never smooth and steady, and the observed temperature data are entirely consistent with the climate models.
Hudson goes on to present two fringe ideas. The first, by Piers Corbyn, is that some undisclosed solar mechanism is "almost entirely responsible for what happens to global temperature." But solar activity over the past years has been at an all-time low since satellite observations began in the 1970s, so if anything, it has worked towards cooling. The second is by Don Easterbrook, claiming that oceanic changes explain global warming of the past decades. But if the oceans were responsible for atmospheric warming, they would have had to release heat to the atmosphere – just the opposite of what the data shows. The oceans are soaking up heat, slowing down global warming.
When questioned by the Guardian's Leo Hickman, the BBC responded that "The point [Hudson's] article is making is that views about climate change are hotly contested." That is not quite right. The article was trying to create the false impression that views about climate change are hotly contested among credible scientists, which they are not. The article did that by dressing up maverick global warming denialists as if they were credible scientists.
Hudson should have made clear that Corbyn has no scientific track record as a "solar scientist": according to the citation database Web of Science, his only peer-reviewed publication was on pebble sizes on Chesil Beach, published in 1967 and never cited since. And Easterbrook, while having a past record as geologist, is retired, has no scientific track record on the specific issue he is talking about and likewise has no peer-reviewed publication that would support his claims. As usual in such articles, reputable climate scientists such as my German colleague Mojib Latif are also cited – but among these there is no disagreement about the basic facts of human-caused global warming.
The BBC's Richard Black argues that if their reporting gets criticised equally from both sides, it must be about right. But for science reporting, I would prefer journalists to stick with more old-fashioned indicators of good science: peer-reviewed publications and personal reputations built on a solid track record of relevant research. And they should remember that old wisdom: extraordinary claims require extraordinary evidence.
• Stefan Rahmstorf is a climate scientist and oceanographer at the Potsdam Institute for Climate Impact Research and author of the upcoming book, The Climate Crisis