NCDC Inflating US Temperatures
By Paul Homewood
Year to Date (Jan – Oct) Temperature
Contiguous United States
According to NOAA, the USA, (or at least the contiguous part), is heading for its warmest year on record. Their records show that the YTD mean temperature at the end of October was 58.36F, or 14.64C, and running about a degree fahrenheit above the previous hottest year of 1998.
But can their figures be trusted? Their data is so full of temperature adjustments as to make the original historical records unrecognisable. Steve Goddard, for instance, has identified the extent of the adjustments that USHCN make. On a more local level, I have shown NOAA’s claim, that Virginia broke the state record temperature for July this year, simply was not borne out by the actual temperature records.
One of the problems many of us encounter is that NOAA seem very reluctant to divulge how they actually arrive at their results. When I challenged NOAA’s Deke Arndt about this, he admitted he did not know himself and could not replicate the calculation for Virginia in 1934, as I had asked.
But we don’t have to take their word for it. Satellite measurements by both UAH and RSS provide atmospheric temperature data for the USA 48. According to them, the temperature increase from last year to this year is not as great as NOAA have made out.
Taking UAH as an example, Figure 1 shows the change in temperature from each month last year to the corresponding month this year.
For most months this year, NOAA/NCDC show much larger increases than UAH do, and, at the end of October, the YTD increase over the same period last year is 1.35C and 0.89c respectively. In other words, NCDC has found an extra 0.46C of warming that UAH cannot find, or 0.83F.
How reliable are the UAH numbers? For a start, they correlate pretty well with RSS, who give a figure of 1.00C. It is possible that there could be short term variations between satellite and surface temperature measurements. However, it is worth noting that, since the satellites started up in 1979, the gap between their measurements and NCDC’s has steadily grown, as the following table makes clear.
|NCDC Mean Temperature / UAH & RSS Temperature Anomalies –USA 48|
Bear in mind that these figures are up to 2011, i.e before the latest divergence. Including the figures so far this year, the total divergence since 1979 amounts to 0.91C between NCDC and UAH, and 0.90C when compared with RSS.
If NCDC figures have been overstated by this sort of amount, the claim that 2012 is likely to be the warmest year on record simply does not hold water.