It’s that time of the year when many of us start thinking about the global annual average temperature. As time goes on I am increasingly thinking about what such a global average means, especially since warming (or lack of it) across the globe is very patchy. Of course, we haven’t got the full data in yet, but here are some thoughts before the statistics are spun.
The RSS AMSU satellite temperatures are in for November. It was 0.033 deg C above the average for the past 30 years. Given the errors that’s indistinguishable from zero. Indeed, if you just look at the first 11 months of each year in the AMSU database 2011 comes 12th out of the 33 annual datapoints. In the past ten years, only one year, 2008, has been cooler up to November. I expect that according to this database 2011 will remain the 12th warmest year.
The Met Office said last year that for 2011 they were expecting another very warm year, with a global anomaly forecast of +0.44 deg C (HadCrut3) above the 1961-1990 average. That would make 2011 the equal 6th warmest year on record.
It won’t be. Whilst we wait for the November and December data 2011 has a temperature anomaly of 0.356 and is the 11th warmest year.
Just last month the Met Office revised their assessment to say 2011 would indeed be the 11th warmest in the 150-year database. They say 2011 continues the long- term trend, which it does, but that does not alter the fact that we now have to look back more than a decade to find comparable temperatures to 2011. Each year is not inexorably warmer than the previous one under conditions of global warming, as there is noise and errors to be taken into account, but surely, the global temperatures must start to rise soon!
2011 saw a moderate cooling La Nina effect that was responsible to lowering global temperatures. This is no doubt something that will be mentioned several times, especially by those who trumpet 2010 as the warmest year on record (in NasaGiss database) and who forget that was because of a strong ELNO effect that year (and the greater incidence of ENSOs than La Ninas in the past decade.)
The only other database that has released November 2011 data is Noaa, and therein lies a curiosity.
November 2011 was cooler than; 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002, 2001.
And warmer than; 2000, 1999, 1998, 1997, 1996, 1995, 1994, 1993, 1992, 1991, 1990.
Months are, of course, very variable, but you see the pattern.
Not long to go now before we have all the data required to put 2011 in its place.