Notes on the February Global Temperature Anomaly

Guest post by John Kehr

With two completed months of the year there is starting to be discussion of how 2013 is shaping up for the annual anomaly.  Several comments around the web have caught my attention as they demonstrate a basic misunderstanding of how the Earth’s climate is behaving.  This is one of those articles that may seem OCD, but this one misunderstanding is what allows warmists to get away with as much as they do when it comes to climate.

I am going to pick on Anthony Watts and Roy Spencer for this one.  The article in question was the one where Roy Spencer provided an update of the UAH anomaly.  Here is a screen shot of the article.

From March 4th, 2013

The title states that there was a big drop in surface temperature in the month of February from ~ 0.5 to 0.2 °C.  This is correct for the anomaly, but it has nothing to do with the Earth’s temperature.  The reality is the Earth warmed up, but the anomaly dropped.

Let me explain.  January is the coldest month of the year for the planet as a whole.  Depending on the source, the average temperature is between 12.0 and 12.5 °C for the month.  February is on average 0.18 °C warmer than January, also source dependent.  Here is what the basic generic behavior of the Earth is on an annual basis.

Illustration 1: Annual Temperature of the Earth and the Northern and Southern Hemispheres. The average temperature of the Earth is different for each month of the year.

This is based on the average from the 1900-1990 data and I have used this extensively as the baseline behavior for the Earth today.  Anomaly has no place on this chart because this shows the actual temperature of the Earth and each hemisphere.  How the seasons affect the global average is readily apparent.  To me it also shows how many factors can influence the global anomaly.  January and February are perfect examples of this.

If I switch to Weatherbell I can show some cool graphics that they produce.

Here is January and February of 2013 from their site.

Notice that the Earth is  about 0.25 °C warmer in February, but since it was closer to average the anomaly was much less.  Climate scientists hate it when people show real temperature because it is impossible to see much warming when you look at the seasonal changes in the actual temperature.

Now for something interesting.  In January the anomaly in the Arctic was well above average.  By simple physics that meant the Arctic was losing energy to space at a much higher rate than average.  Normally the Arctic is losing energy at a rate of 163 W/m^2.  In January of 2013 it was losing energy at a rate of 173 W/m^2.  That 6% increase in rate of energy loss meant that the Arctic ended up with a negative anomaly in February.  The dramatic change in Arctic anomaly played a big role in the drop of the global anomaly in February.

The rate of energy loss is a self-correcting mechanism.  Physics don’t allow it to operate in any other way.  As a whole the Earth lost ~ 4 W/m^2 more than average over the entire surface in the month of January.  Data for February is not yet available, but it will be close to average because the anomaly was closer to average.  The higher rate of energy loss in January resulted in a more average February.  That is how the climate operates.

Finally I have to get a dig in at CO2.  In January of 2013 it was 395 ppm and in 1985 it was 50 points lower at 345 ppm.  So despite the fact that CO2 was higher, the Earth was losing energy at a higher rate to space.  CO2 was not blocking the energy from escaping despite all the claims that increased CO2 prevents heat from escaping the Earth.  The Earth 30 years later was losing a significantly larger amount of energy to space than it was in the past.

Science, ignore at your own peril.