For those of you how look at the world climate widget on the right hand side of my blog may have been puzzled by the last update with the December 2010 temperature. The temperature anomaly is now at +0.18C, while it was "much" higher just a month ago. There are two reasons for this:
1) The global temperature is decreasing really fast as a result of the transition from El Nino to La Nina conditions last year.
2) There is a change in the base line for the anomaly.
The reason for the base line change can be found on Roy Spencer's blog:
"NEW 30-YEAR BASE PERIOD IMPLEMENTED!
Sorry for yelling like that, but if you have been following our global tropospheric temperature updates every month, you will have to re-calibrate your brains because we have just switched from a 20 year base period (1979 – 1998) to a more traditional 30 year base period (1981-2010) like that NOAA uses for climate “normals”."
So, no need to worry this is just a small offset update as it has no implications of the actual interpretation of the data.