Sunday, January 29, 2012

2011 Global Temperatures and A Look Ahead

There are three organizations that regularly analyze the global temperature record on an annual basis.  The three international global temperature data sets are from the Met Office and University of East Anglia (HadCRUT3), NOAA National Climatic Data Center (NOAA NCDC) and NASA Goddard Institute of Space Studies (NASA GISS).  Final figures from HadCRUT3 will not be available until March, 2012.  While the other two are also preliminary, the additional data yet to come will not likely change the findings.

This is what the three data sets looked like together as of October, 2011:

Image credit: UK Met Office.

NASA GISS recently released its figure for all of 2011.  The year was the ninth warmest on record according to its analysis.  Meanwhile, HadCRUT3 and NOAA NCDC listed this past year as the eleventh warmest on record.

Global temperature anomalies 1880-2011.  Image credit: NASA GISS

Why the difference?  Each dataset is slightly different in the number of stations analyzed.  In addition each one uses a different baseline for the normal temperature.  For example, GISS compares the years with normals from 1951-1980, while HadCRUT3 uses 1961-1990.  Meanwhile, NOAA NCDC uses a twentieth century mean.

NCDC compared the global temperature record with the El Nino/La Nina years.  It turns out the 2011 was a La Nina year and it was the warmest La Nina year since 1950 when the index was started.  You can see that El Nino years are often warmer than La Nina years.

The graph and map are from NOAA/NCDC.
It appears that the 5 year mean has leveled off, but this does not mean that global warming has stopped.  In fact, you can see a number of instances where it levels off, but the trend continues.  This was recently illustrated by the website Skeptical Science using the Berkeley Earth Surface Temperature (BEST) data.

La Nina is beginning to fade and will likely disappear in the spring or early summer.  What does this mean for global temperatures?  We have two outlooks, both of which are similar.

First is from Dr. James Hansen of NASA GISS.  Hansen said he expects record-breaking global average temperature in the next two to three years because solar activity is on the upswing and the next El Nino will increase tropical Pacific temperatures. The warmest years on record were 2005 and 2010, in a virtual tie.

"It's always dangerous to make predictions about El Nino, but it's safe to say we'll see one in the next three years," Hansen said. "It won't take a very strong El Nino to push temperatures above 2010."

The next is from the UK Met Office.  Adam Scaife, Head of Monthly to Decadal Forecasting at the Met Office said: "While 2010 was a record warm year, in 2011 we saw a very strong La Niña which can temporarily cool global temperatures.

"The La Niña has returned and although it is not as strong as early last year, it is still expected to influence temperatures in the year ahead. Therefore we expect 2012 to be slightly warmer than last year but not as warm as 2010."

The UK Met Office goes on to say that 2012 is expected to be around 0.48 °C warmer than the long-term (1961-1990) global average of 14.0 °C, with a predicted likely range of between 0.34 °C and 0.62 °C.  This compares with their value for 2011 of 0.36 °C.  Their forecast for 2011 was of between 0.28 °C and 0.60 °C, with a most likely value of 0.44 °C above the long term average.  If their value for 2012 is realized, that would make it the third warmest year on record.

Both agencies expect the 2010 record to be broken in the next three years.  This has been their outlook for the past couple of years.  Bottomline: global temperatures continue to rise, but exactly how they will impact this region (southeastern U.S.) is hard to say.  It is safe to say that there will be impacts.