Global weather: 2010 in running to be warmest year on record

This year is on track to enter the almanac as one of the three warmest years on record globally, along with 1998 and 2005, according to a preliminary analysis by the World Meteorological Organization.

Not only that, but 2010 stands a decent chance of capturing the record, depending on temperature data from November and December, according to Michel Jarraud, secretary-general of the WMO. Global average temperatures for the first 10 months of the year are running slightly ahead of those for the same period in '98 and '05, he noted during a press briefing Thursday at UN-sponsored climate talks under way in Cancun, Mexico.

Preliminary temperature data for November are comparable to temperatures seen in November 2005, indicating they have remained near record levels as the year winds down.

Even if 2010 fails to capture the top spot, the first decade of the 21st century already has gone into the books as the warmest since 1850, when the instrument record began.

The data are part of the WMO's annual roundup of global weather activity, especially extreme events such as floods, heat waves, deep cold snaps, and severe storms.

Some climate scientists caution that any one year's worth of events is driven more by natural variability than by long-term warming triggered by the released of carbon dioxide from burning fossils fuel. But when 2010's extreme events are seen in that broader context, they appear to fit long-term patterns the climate models have generally projected for a climate system responding to increasing atmospheric concentrations of greenhouse gases.

A range of studies have documented an increase in extreme heat events, a decrease in extreme cold events, and an increase in rainfall and snowfall intensity globally during the past 50 years, atmospheric scientist Gerald Meehl, with the National Center for Atmospheric Research in Boulder, told the House Energy and Environment subcommittee last month.

On the basis of physical principles alone, "we could expect to see just these kinds of changes in extremes in a warming climate," he testified.

In the US alone, he noted, the past decade saw high temperature records being set twice as often as low-temperature records, whereas in a climate without the additional greenhouse gases humans have pumped into the atmosphere, the ratio would average over the long term about 1 to 1. So far in 2010, the ratio was closer to 3 to 1, he said. Meanwhile, precipitation intensity has increased over the past 50 years, traced to the additional moisture the atmosphere can hold when it warms.

Some of the events in 2010 the WMO found noteworthy:

• Unusually heavy monsoons in Pakistan that brought the worst flooding in that country's history. The floods forced 20 million people to leave their homes and covered a significant portion of the country's farmland. At least 1,500 people were killed in the flooding, according to international relief groups.

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