In particular, a few computers at NASA's Goddard Institute seem to be having a disproportionate effect on global warming. Anthony Watt takes a cut at an analysis I have tried myself several times, comparing raw USHCN temperature data to the final adjusted values delivered from that data by the NASA computers. My attempt at this compared the USHCN adjusted to raw for the entire US:
For graphics and more info click here
Anthony Watt does this analysis from USHCN raw all the way through to the GISS adjusted number (the USHCN adjusts the number, and then the GISS adds their own adjustments on top of these adjustments). The result: 100%+ of the 20th century global warming signal comes from the adjustments. There is actually a cooling signal in the raw data:
For graphics and more info click here
Now, I really, really don't want to be misinterpreted on this, so a few notes are necessary:
Many of the adjustments are quite necessary, such as time of observation adjustments, adjustments for changing equipment, and adjustments for changing site locations and/or urbanization. However, all of these adjustments are educated guesses. Some, like the time of observation adjustment, probably are decent guesses. Some, like site location adjustments, are terrible (as demonstrated at surfacestations.org).
More...
