A research project founded by a climate change skeptic has concluded that the planet is getting warmer, with land temperatures rising by one degree Celcius since the 1950s.
Last year, Berkeley physicist Richard Muller said he was dubious about the validity of existing studies tyhat appeared to show the world was warming, and set up the Berkeley Earth Surface Temperature project to review the vast amount of data collected so far.
BEST examined data from over 39,000 unique stations - more than five times the number used by the Global Historical Climatology Network Monthly data set, the focus of many climate studies in the past.
Muller said he was particularly interested in whether the so-called heat island effect of cities - where most monitoring stations are found - has skewed the results. And so, as part of the BEST study, the results from the total set of weather stations was compared with those from rural stations only.
And the conclusion? That the data so far is reliable. In fact, the study concludes, the trend is "opposite in sign to that expected if the urban heat island effect was adding anomalous warming to the record."
The report concludes: "Global warming is real".
It's not convinced everybody, however. Blogger Anthony Watts, for example, points out that the BEST papers haven't yet been peer-reviewed.
"I had very high hopes for this project as the methodology is looked very promising to get a better handle on station discontinuity issues with their 'scalpel' method," he says. "Now it looks just like another rush to judgement, peer review be damned."
Watts questions the methodology of the research, on the basis that BEST has measured data over a longer time period than previous studies, and weather stations have moved during that time.
"Our ratings from surfacestations.org are assumed to be valid for the 1979 – 2008 period, but with Muller et all doing analysis from 1950, it renders the station survey data moot since neither Menne et al nor Fall et al made any claim of the station survey data being representative prior to 1979," he says.
He adds: "I know that I’ll be critcized for my position on this, since I said back in March that I would accept their findings whatever they were, but that was when I expected them to do science per the scientific process."
The BEST papers have been submitted for peer review, so we should find out what other scientists think soon. In the meantime, they're available here.