When it comes to climate change, I’m prepared to accept that some people have differing views on why the earth might be warming. Those that hold out that the earth hasn’t warmed are a different matter. Plenty of such people exist, and many of them justify their views with criticisms of the data sources that are generally used by climate scientists, such as NASA and Hadley CRU. In particular, there are complaints that weather stations are badly placed, that they do not take the urban heat island effect into consideration, and that scientists are selective in their use of data.
In response to these sorts of questions, the Berkeley Earth Surface Temperature project (BEST) set out to consolidate the land temperature record once and for all. It’s a major undertaking, incorporating results from over 39,000 weather stations – 5 times as many as previous studies, and comprising 1.6 billion measurements of land temperatures. BEST uses a very broad set of temperature records, and for the first time, includes analysis of weather station quality. It is independent, transparent, and ground-breaking in its scope and methodology.
Because it so directly addresses the concerns of skeptics, BEST has attracted considerable attention from those who dispute global warming. The Koch Foundation helped to fund the project, and skeptic author Fred Singer endorsed it. Meterologist Anthony Watts contributed data and was confident enough to nail his colours to the mast: “I’m prepared to accept whatever result they produce,” he wrote in March, “even if it proves my premise wrong.”
Last week, the results were released for peer review. “The BEST study finds reliable evidence of a rise in average world land temperature of approximately 1 degree C since the mid 1950s.” If you’ve been paying attention, that’s exactly what previous studies showed.
What of the station quality? Stations rated ‘poor’ showed exactly the same trends as those rated ‘ok’ by Watt’s team. (This should be obvious: a weather station in a car park may be recording higher temperatures than one in a field, but it will do so consistently. The individual readings will be too high, but the change in temperatures over decades would be the same and the trend would still be visible.)
As for the urban heat island effect, the study found that it is real, but since less than 1% of the earth’s surface is built on, it “does not contribute significantly” to average land temperatures.
In other words, what we have in BEST is a rigorous study that directly and transparently addresses the concerns of some of the world’s most prominent climate skeptics, that uses their own research data and consulted them on methodology, that enjoyed their full blessing, and then systematically proved their concerns to be misplaced. Has Watts acknowledged the results, as he said he would? Of course not.
But for the rest of us, we can have confidence in the temperature record. The earth has warmed.