Global warming "plateau?"

The world has warmed just under 1 degree Fahrenheit -- 0.86 -- since the late 1970s, based on NASA satellite measurements, according to John Christy at the University of Alabama.

But Christy said this afternoon that since the waning of a powerful El Nino -- the warming of surface waters in the tropical Pacific -- in 1998, world temperatures have been "relatively stable."

Satellites profile the bottom 25,000 feet of the atmosphere, and the database is maintained by Christy and Roy Spencer, viewed as environmental pariahs by some of their critics.

In the surface database maintained by the National Climatic Data Center, in Asheville, N.C., the years 2005 and 2010 tied for the warmest globally in the period of record, dating to 1880.

Last year was the 11th warmest.

Christy says that the warming in the last 34 years "is consistent with the low-end of global climate change predictions made by some climate models."

In an addendum almost sure to draw fire, he added, "It is also within the potential range of natural climate variability."

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