Has the US Been Cooling? (No.)

Anthony Watts tells us that the continental US is cooling on alternate Tuesdays in months that have two full moons.

OK, the cherry-picking isn't quite that bad, but almost. He tells us that Burt Rutan tells him that winters are cooling in the USA-48 at vast rates of up to 8°F per decade! (At that rate we'll disprove the Third Law in about 600 years -- yet again proving the consensus wrong!) And that the whole USA-48 is cooling at -0.87°F/decade for the last 10 years.





People, let's get a grip.

First of all, the USA-48 is only 5.4% of the Earth's land area, and 1.6% of its total area. We aren't the world, as the song (doesn't) go.

Second, a 10-yr time span is meaningless. There are too many natural fluctuations of order 0.2-0.3°C to pick out a manmade trend. Deniers keep ignoring this because the last 10-yrs is about all they have left to bitch about. Santer et al found that at least a 17-yr time interval is needed to pick out an anthropogenic component from global average surface temperature:


Santer, B. D., et al. (2011), “Separating Signal and Noise in Atmospheric Temperature Changes: The Importance of Timescale,” J. Geophys. Res., doi:10.1029/2011JD016263, in press.
http://www.agu.org/pubs/crossref/pip/2011JD016263.shtml

Third, other data and other simple calculations don't find these results. I'm using the USA48 data from UAH, because it's what I have handy in a spreadsheet. (It's in the last column.) You can slice the data up in all kinds of ways; here are three:

• The change in the 10-year moving average over the last 10 years is +0.10°C.
• The 10-year change in the 12-month moving average is +0.24°C.
• The slope of the last 10-years/120-months is -0.007 ± 0.008°C/decade. That is, it's not statistically significant.

I'm sure you can cherry-pick something out of the BEST or UAH data that finds cooling for some temperature-like aggregation of some 10 year set of the data, but you need to try rather hard. It will probably help if you first stand on your head.

PS: Notice how they have all suddenly switched to Fahrenheit, because it makes the numbers 1.8 times larger?