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2010: An Even More Unexceptional Year

Dr David Whitehouse

Following my analysis of 2010 based on Met Office temperature data it has been suggested that I perform my analysis on other global temperature data sets that are more comprehensive. It has also suggested that when I do I will arrive at a different result, and that all of the months in 2010 have been anomalously warm.

Well, here it is.The first data set, from the UK Met Office, is here.

January was cooler than January in 2007, 2005, 2004, 2003, 2002 and 1998. SAME.

February was cooler than February in 2007, 2004, 2002, and 1998. SAME.

March was exceptionally warm. However it was, given the errors, statistically comparable with March 2008 and March 1990. SAME.

April was cooler than April 2007, 2005, and 1998. SAME.

May was cooler than May 2003 and 1998. SAME.

June was exceptionally warm though statistically identical to June 2005 and 1998.SAME.

July, when things started to cool, was cooler than July 2006, 2005 and 1998. SAME.

August was cooler than August 2009, about the same as 2005, and cooler than 2001 and 1998. REVISED. August was now cooler than 2006 as well.

September was cooler than September 2009, 2007, 2005, 2001 and 1998.REVISED. September was cooler than 2009, 2007, 2005.

October ­ the last month for which there are records was cooler than October 2009, 2008, 2007, 2006, 2005, 2004, 2003 and 1998. SAME.

The same analysis can be performed on the other two commonly used global temperature datasets.

Firstly, NOAA.

January was cooler than 2007, 2003 and 2002.

February was cooler than 2003, 2002, 1999, and 1998.

March was exceptionally warm, statistically equal to 2002.

April was exceptionally warm, statistically equal to 1998.

May was roughly equal to 2005 and cooler than 1998.

June was roughly equal to 2005 and cooler than 1998.

July was roughly equal to 2005 and cooler than 1998.

August was cooler than 2009, 2007, 2006, 2005, 2003, 2001, and 1998.

September was cooler than 2009, 2007, 2006, 2005, 2004, 2003, 2002 and 2001.

October was cooler than 2009, 2008, 2006, 2005, 2004, 2003, 2002, and 2001.

November was cooler than 2004 and about the same as 2005 and 2001.

It is possible that 2010 will tie with 1998, or possible exceed it in this database (though it would not be statistically significant.) If it does so it would be due to the warm months March – June due to the El Nino and not the sign of AGW.

Using the NASA dataset the results are:

January was cooler than 2007, 2005 and 2002.

February was cooler than 1998.

March was cooler than 2002.

April was the warmest on record.

May was cooler than 1998.

June was cooler than 2009, 2006, 2005, and 1998.

July was cooler than 2009, 2008, 2007, 2005, 2003, and 1998.

August was cooler than 2009, 2006, 2005, 2003, and 1998.

September was cooler than 2009, 2006, 2005 and 2003.

October was cooler than 2005 and 2003.

November is the warmest November on record. Although the temperature increases more often than not between October and November in this dataset (in the past decade at least) the 2010 jump is larger than usual making November comparable to January, February and April 2010, but cooler than March 2010. Curiously this increase is all in the Northern Hemisphere, whilst the Southern Hemisphere has cooled. The November data takes the reading for the year to 0.57, the same as 2009, and statistically identical to 2006, 2003 and 1998 in total, but less than 2007 and 2005 in total.

These databases give the monthly temperature to thousandths of a degree which is superfluous. When rounded up to a more physically sensible 0.1 deg almost all of the differences between the years of the past decade go away, but that is another story, and not the subject of this post.

The suggestion that all the months this year in the CRU, NOAA and NASA global datasets for which data has been collated (January – October) were anomalously warm is incorrect, as even the most cursory examination of the datasets shows. They are, of course, warm when compared to years before about 2000. But in the context of the past decade they are not unusual.

Placing months in rank order like this is an instructive exercise, but not an infallible indication of 2010’s position. It is clear however that with the months of 2010 so well mixed with the months of the past decade that there is no trend in this decade showing again that the data of the recent warming spell that began about 1980 is not linear and that many more years of data are required to put the past decade’s temperature standstill into perspective.

Clearly looked as a whole 2010 is a very warm year and, given the El Nino, it is not impossible that in the NASA dataset the months might average out as the warmest. But it would be misleading to take this as significant given the errors will certainly make it a statistically insignificant increase over the years of the past decade. It is also more an artifact of the variation in temperature seen during previous years. The fact is that the individual months of 2010 are, with the exception of the El Nino Spring, well mixed with years of the previous decade. This is testimony to the fact that whilst we live in a warm decade, it has not gotten any warmer for a decade. We are on a somewhat noisy plateau of temperature that makes the trend in the data of the past decade or so flat.  For a year to go against this trend most of its years would have to exceed the temperature of all previous years and as once can see with eleven months data available for NASA nine of them are cooler or the same as previous years (ten each for the CRU and NOAA with data to October).

The result of using the different databases is even more stark than my original analysis.

The conclusion is therefore even more solid about 2010 being an even more unexceptional (in the context of the past decade) El Nino year with a warm Spring.