Earlier this month, I reported the satellite temperature trend data from University of Alabama in Huntsville climatologists John Christy and Roy Spencer who reported for the 48 contiguous U.S. states that 2012 was the warmest year in the 34-year satellite record:
The annual average temperature over the conterminous 48 states in 2012 was 0.555 C (about 0.99 degrees F) warmer than seasonal norms.
Yesterday, the National Oceanic and Atmospheric Administration released their data for 2012 and also reported that 2012 was the warmest year on record for the lower 48 states:
2012 marked the warmest year on record for the contiguous United States with the year consisting of a record warm spring, second warmest summer, fourth warmest winter and a warmer-than-average autumn. The average temperature for 2012 was 55.3°F, 3.2°F above the 20th century average, and 1.0°F above 1998, the previous warmest year.
Most of the difference between the UAH data (+1 degree F) and NOAA data (+3.2 degree F) can be accounted for by differences in their baselines, 34 years versus the 20th century. All temperature records do show an upward trend in global average temperatures. See below:
Looking at the above five different global temperature datasets through 2010 from the Goddard Institute for Space Science (GISS), NOAA's National Climate Data Center (NCDC), University of East Anglia's Hadley Center (HadCrut), Remote Sensing Systems (RSS) and University of Alabama in Huntsville (UAH), one finds the following per decade trends:
GISS + 0.176 degree C
NCDC + 0.171 degree C
HadCrut + 0.169 degree C
RSS + 0.163 degree C
UAH + 0.141 degree C
The difference in the rate of increase between the highest and the lowest datasets is +.035 degrees per decade. Another way to cumulate the difference, assuming a linear rate of increase for the next 100 years, is that global average temperatures will have increased above the current average by between 1.76 to 1.41 degree C by 2113.