July hot all over the world

Worldwide, last month just missed becoming the warmest July in the satellite dataset, according to John Christy, keeper of the satellite archive.

It did tie for the second-warmest July and was the 17th-warmest month overall in the monthly satellite records, which date to December 1978.

What was puzzling about the July warmth, said Christy, director of the Earth System Science Center at the University of Alabama, in Huntsville, was that it coincided with a rapid cooling of the tropical Pacific.

During the winter, that region was in a state of El Nino, an anomalous warming of the sea-surface temperatures, but the waters have cooled rapidly and radically.

Of the overall world temperature rise, Christy said, "No one would have predicted this."

That said, the warmest July on record, 1998, occurred as the Pacific was cooling off after one of the strongest El Ninos ever.

July 2010 was a mere 0.05 degrees Fahrenheit cooler than July 1998, Christy said.

The temperature readings are derived from microwave sounding units on government satellites that measure temperatures from the Earth's surface to 5 miles deep into the atmosphere.