Those who believe the science of climate change – oops, sorry, make that “Al Gore’s climate change” – to be based on a single dataset relating to a single country have been greatly excited by the news that NASA has made a 0.03ºC adjustment in the respective temperature figures for 1934 and 1998, leading to the temperature anomaly for the US in 1934 now being considered to have been 0.02ºC more than in 1998, rather than 0.01ºC less as previously thought. (See here for an explanation of “temperature anomalies” as a measure of temperature trends.)
I know, I know: sensational stuff. Blows the whole science of climatology out of the water. Guess I can go ahead and buy that SUV after all.
Actually, for all my sarcasm in the preceding paragraphs, I was troubled by these figures (and by the crowing they had engendered among climate-change sceptics), so decided to look for more details on what their implications were. I found a very helpful post on the RealClimate blog, in a post written by NASA climatologist Gavin Schmidt, on which the figures in my opening paragraph are based.
“Another week, another ado over nothing”, Schmidt begins, before describing the process by which this small, low-key recalculation had been made. Apart from emphasising how small the adjustments are (in contrast to the sensationalist tone of some of the coverage), some key points made by Schmidt are:
- Climatology is about long-term trends, not one-off events, and “the longer term US averages have not changed rank. 2002-2006 (at 0.66 ºC) is still warmer than 1930-1934 (0.63 ºC – the largest value in the early part of the century) (though both are below 1998-2002 at 0.79 ºC)”.
- The affected data only relates to the US anyway: “In the global mean, 2005 remains the warmest (as in the NCDC analysis)”.
Sum total of this change? A couple of hundredths of degrees in the US rankings and no change in anything that could be considered climatically important (specifically long term trends).
Coming next on Fox News: why that 1.2 million square kilometres of “missing” Arctic sea ice was never there in the first place.
Update: There’s a very good article in the latest SciAm on The Physical Science behind Climate Change (you’ll need to cough up $4.95 to download the PDF of the magazine, but it is well worth it if you’re interested). And New Scientist’s “round-up of the 26 most common climate myths and misconceptions” is essential reading when assessing the claims made by climate-change sceptics.