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Tuesday, January 21, 2014

James Hansen et al: Global Temperature Update Through 2013

http://www.columbia.edu/~jeh1/mailings/2014/20140121_Temperature2013.pdf

 Summary. Global surface temperature in 2013 was +0.6 °C (~1.1 °F) warmer than the 1951-1980 base period average, thus the seventh warmest year in the GISS analysis. The rate of global warming is slower in the past decade than in the prior three decades. Slower growth of net climate forcings and cooling in the tropical Pacific Ocean both contribute to the slower warming rate, with the latter probably the more important effect. The tropical Pacific cooling is probably unforced variability, at least in large part. The trend toward an increased frequency of extreme hot summer anomalies over land areas has continued despite the Pacific Ocean cooling. The “bell curves” for observed temperature anomalies show that, because of larger unforced variability in winter, it is more difficult in winter than in summer to recognize the effect of global warming on the occurrence of extreme warm or cold seasons. It appears that there is substantial likelihood of an El Niño beginning in 2014, and as a result a probable record global temperature in 2014 or 2015. 

 The update through 2013 of the GISS (Goddard Institute for Space Studies) global temperature analysis[1]  (Fig. 1), available in detail on the GISS web site (www.giss.nasa.gov/gistemp), reveals 2013 as slightly warmer than the preceding two years and nominally the 7th warmest year in the GISS analysis. 

 Although there are several sources of error in the estimated temperature, the biggest error in comparing global temperature for nearby years is from the incomplete spatial coverage of data. Uncertainty between nearby years is a few hundredths of a degree Celsius[1]. Thus, accounting for this uncertainty, we say that 2005 and 2010 tie for warmest year, 1998, 2002, 2003, 2006, 2007, 2009 and 2013 tie as the 3rd through 9th warmest, and 2012 is the 10th warmest. The 14 warmest years all occurred since 1998 (including 1998). Large year-to-year temperature fluctuations in Fig. 1are caused mainly by natural oscillations of 
tropical Pacific sea surface temperatures as summarized by the Niño index (lower part of Fig. 1), which we illustrate with higher resolution in a later figure.

 [Please see the rest at the link above.]
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2 comments:

Anonymous said...

I am curious, do the temperature readings used to measure the global temperature add in the additional planetary heat absorbed to allow the polar ice melts? Because it takes much more heat absorption to melt ice than to raise the temperature of water. So, I suspect that the ocean temperature will rise much faster as planetary ice melts. Is this not a correct assumption?

January 21, 2014 at 12:48 PM
Tenney Naumer said...

If you are referring to global average surface temperatures, I believe they are calculated from instruments that measure at a height of 2 meters. There are some extrapolations made and some measuring stations' data is eliminated if considered faulty.

The extra energy you are referring to may be something that is used in climate models, however. Although, I think modeling of the Arctic is not very good, and we can see from the newest CMIP5 modeling results. CMIP5 models are better than CMIP3, but not by much.

Ocean temperatures are measured and stated by depth. Latest data shows the depth of 700 meters is retaining a lot of the extra heat, but the ocean is so very large that this amounts to about a 0.1 degree Celsius increase. However, much of the heat is going into the deep ocean. But worse, some heat is not passing from the surface to depth and is heating up a lot in the western Pacific, causing a 20 cm rise in sea level and increasing storm frequency, intensity, and rainfall, with all the attendant consequences, none good.

January 22, 2014 at 2:05 PM

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