The BEST (Berkeley Earth Surface Temperature) project team has (after much problems) issued their paper “A New Estimate of the Average Earth Surface Land Temperature Spanning 1753 to 2011″ in the brand new journal GIGS (Geoinformatics and Geostatistics). The overall style of writing is very clear, and the project team must be congratulated for their openness, even if one does not accept all conclusions.
I just want to muse here on one very important issue. The diurnal temperature trend (DTR) is really one big fingerprint of global warming, according to the climate models. Global warming should lessen DTR, as nocturnal temperatures are expected to rise faster than the daily maxima. To their great surprise, BEST finds a curious behaviour in the global DTR over land:The surprise lies in the unsuspected rise of DTR since about 1985, which badly hurts our confidence in the skill of global climate models. Note the very visible swings during the decade from 2000 on. As an exercise in curiosity I magnified the graph and fetched the values for the period 2002 to 2011. The following figure shows the regional situation at Diekirch and the global one as given by BEST (BEST data from 2002 to 2011, Diekirch data from 2002 to 2012)
This might be a coincidence, but if you read the new updated trends for Diekirch, all major data point to an absence of warming during the last 8 years at least. It seems here in Luxembourg nobody does take notice, as fostering climate Angst seems so rewarding. Hello, you political and enviro guys… do you hear me?
added 23 Jan 2013:
There is an interesting PhD dissertation by Knut Makowski from ETH Zürich on the link between DTR and Surface Solar Radiation (SSR). He finds a reversal of the declining DTR trend in the mid-1970′s for Western Europe: