WEATHER A record year for warmth

Most of the rise in average global temperature has been over the past three decades.
SCRIPPS HOWARD
It's not over yet, but already 2003 appears destined to be the planet's third-warmest year on record, the National Oceanic and Atmospheric Administration said Tuesday.
The average global temperature for this year will likely be 58 degrees Fahrenheit, just a fraction of a degree under the averages for 1998 and 2002, the warmest and second-warmest years since modern record-keeping began in the late 19th century, according to NOAA's National Climatic Data Center in Ashville, N.C.
The 10 warmest years have all occurred since 1990. In the past century, average global surface temperatures have increased by 1 degree Fahrenheit, but most of the increase has occurred in the last three decades.
Through November, temperatures for the year were as much as 3 degrees F above average across large parts of Asia, Europe and the U.S. West. Higher temperatures and shifts in atmospheric circulation patterns in 2003 also contributed to a second straight year of extremely low Arctic sea ice.
At the extremes
This year has been notable for extreme weather events in the United States and around the world. Europe suffered an extraordinary heat wave in late July and August that broke temperature records across the continent. The United Kingdom broke its maximum temperature record Aug. 10, when the mercury reached 100.6 degrees F at Gravesend-Broadness in Kent. More than 14,000 people died of heat-related causes during the peak of the European heat wave.
Continued drought plagued the western United States, parts of which have been in almost continuous drought for over five years. As of the end of November, 11 states in the West were experiencing moderate-to-extreme drought, and reservoirs were well below normal in many places.
In the East, unusually wet conditions prevailed. This year is already the wettest on record for Richmond, Va., and Baltimore and Washington are within striking distance of setting new annual precipitation records. The present record for both cities dates back to 1887.
What's the cause?
Most scientists attribute the warming over the past century primarily to atmospheric increases in carbon dioxide, a greenhouse gas caused by human burning of fossil fuels.
The string of record warm years and Europe's heat wave are "consistent with what is expected with climate change," said Jay Lawrimore, the data center's chief of climate monitoring. "However, while you certainly expect to see more extreme events, you can't attribute [any] one event itself to climate change."
Earlier this month, two of the government's top atmospheric scientists -- Thomas Karl, director of the climatic data center, and Kevin Trenberth, director of the climate analysis section at the National Center for Atmospheric Research in Boulder, Colo. -- said there is no doubt that human activity is already having a measurable impact on global climate.
Karl and Trenberth predicted, in an article published in the journal Science, that if current trends continue, the world would face the fastest rate of climate change in at least the past 10,000 years. This could radically change weather patterns, including more frequent heat waves, droughts, floods and extreme storms.
"Climate change is truly a global issue, one that may prove to be humanity's greatest challenge," the scientists wrote.