World Record Myopia

Nature 438, 1062 (22 December 2005) | doi:10.1038/4381062a
The heat was on in 2005
Robert Henson

As 2005 draws to a close, climate scientists are making their annual pronouncements on how its temperatures compare to historical records. And although this year is among the warmest ever recorded, small differences in the claims highlight the uncertainty of such rankings.

Depending on whom one believes, 2005 will end up just above or below 1998 as the hottest year on record. Most significant, climate scientists say, is that this year's readings occurred without the help of a major El Niño event. "In just seven years, the background global temperature has increased to a level equal to the peak in the 1997–98 El Niño," says James Hansen, a researcher at NASA's Goddard Institute for Space Studies in New York City.

That record-breaking El Niño slathered the tropical Pacific with anomalously warm sea water. There was no such event this year, but many other regions were notably warm — including the North Atlantic, where an unprecedented number of tropical cyclones formed.

Hansen says that NASA is likely to dub 2005 as the warmest year on record, but a team at the University of East Anglia in Norwich, UK, is poised to rate it as number two, behind 1998. And a preliminary report from the National Oceanic and Atmospheric Administration (NOAA) shows a photo finish between the two years, with 1998 ahead by a nose (see 'Sources of disagreement'). Final rankings will be released over the next few weeks.

This year's heat was not a total surprise — NASA predicted early in 2005 that it would be one of the warmest years on record. Over the past century, says NASA, Earth's average surface temperature has risen 0.8 °C, with three-quarters of that occurring since the 1970s. Nine of the ten warmest years on record have occurred since 1995.

Hansen, who compiles the annual rankings for NASA, says the recent warming is consistent with the increase in heat-trapping greenhouse gases in the atmosphere. "Climate change is real and should begin to be noticed by real people," he says.

Although differing rankings for 2005 might puzzle the public, it is less of an issue for the scientists who compile them. Most of the time, the ratings agree. "People sometimes make too much of whether a year is ranked warmest or second warmest," says Jay Lawrimore, who oversees month-to-month tracking for NOAA...

There is one crucial difference between 1998 and 2005.

In 1998, we were approaching the maximum peak of the 11 year solar activity cycle. In 2005, we should be near the minimum.



In other words, we are now having record or near record global temperature averages at a time when the earth should be the coolest in the solar cycle.

Shorter Dear Leader: Pass the Kool-Aid.