Global cooling

Ever so slightly, January finished just below long-term averages in the satellite data, according to the monthly temperature report released this afternoon.

The global temperature was a mere 0.02 Fahrenheit below the 30-year January average, but of significance is that it ended a run of 18 consecutive months of above-normal readings, according to the University of Alabama's John Christy, keeper of the data for NASA.

It also was only the second month in the last 2 1/2 years in which temperatures finished below normal.

The big factor, says Christy, is the obvious one -- the La Nina cooling event in the equatorial Pacific.

This is one of the strongest ever, and it covers an area of millions of square miles.

The cooling supplanted last year's impressive El Nino, which helped drive the 2010 temperature to record heights.