A brief update on global warming.  As expect 2010 came in high – the equal-hottest year ever, tying with 2005, according to both NOAA and NASA.  This is despite a strong La-Niña condition developing in the second half of 2010, and low solar irradiance, both of which tend to cool the planet.

As an alternative to plots shown in previous posts, here is NASA’s compilation of annual mean temperatures compiled by four separate institutions.  They show the overall strong agreement among the estimates.  Japan Met’s recent estimates are a little below the others, but the others are in rather close agreement.

NASA's comparison of global mean temperature estimates from four institutions.

Another development is James Hansen’s use of a 12-month running mean, rather than calendar-year means, shown below (only up to June 2010).  This has the advantage of not artificially dividing high or low segments, thus reducing their apparent significance.  It also shows the effect of the El Niño – La Niña cycle much more clearly, along with the cooling effects of some major volcanic eruptions..

12-month running mean temperature, compared with El Niño and volcanic eruptions.


As I posted recently, the case for this warming being due to human activity is becoming more compelling all the time.  It is past time critics could complain that their was no direct evidence for what they call Anthropogenic Global Warming.

It is also past time anyone tried to argue global warming stopped in 1998.  The second plot above clearly shows how the strongest El Niño on record correlates with an unusually high temperature anomaly, compared with the overall warming trend.

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