Well now we know, and I for one think it is worth the wait. Assuming this stands up to further scrutiny, and I have every confidence it will, this is a big deal. These are only initial thoughts. Watts et al. 2012 confirms so much of what many of us have thought – that site, surroundings and equipment matter. Its provides a ‘we told you so’ moment for quality, attention to detail and due diligence. And, yes this may be US data only, but it pulls the rug from under the claims of runaway warming in the last two decades (hint – part of it is runway warming ;-)).
It is a surprise to see so many issues – Rural/Urban, Airports, ASOS/CRS/MMTS and adjustments, undermined together.
Running through the images on the Powerpoint file, the significance gradually sank in and with each new slide my excitement rose. First the highest quality raw stations have just over half the trend of all adjusted ones, then non-airport sites have half the trend of those at airports.
Looking at high quality ‘rural stations only’ gives almost the same (lower) trend as removing airports, but, once again, rural sites not at airports have a still lower trend.
And how was this achieved? Why by good old-fashioned measurement and checking against new classification data of course. It seems eminently sensible that heat bias should be estimated, not just by distance to a heat sink or source, but also by the size of the source (the area of concrete or whatever) – a World Meteorological Organisation endorsed method for heaven’s sake.
Now that this cat is out of the bag (and among the pigeons) it is going to be hard to make it go away as it sets a new standard where others must play catch up; it also takes away a few favourite toys (adjustments). Anyone who overlooks the significance of this paper just hasn’t thought it through.