2004 Was Fourth-Warmest Year Ever Recorded
February 10, 2005
By ANDREW C. REVKIN, NY Times
Last year was the fourth warmest since systematic temperature measurements
began around the world in the 19th century, NASA scientists said yesterday.
Particularly high temperatures were measured over Alaska, the Caspian Sea
region of Europe and the Antarctic Peninsula, while the United States was
unusually cool. But the global average continued a 30-year rise that is "due
primarily to increasing greenhouse gases in the atmosphere," said Dr. James
E. Hansen, director of NASA's Goddard Institute for Space Studies, in
The main source of such gases is smokestack and tailpipe emissions from
burning coal and oil.
The highest global average was measured in 1998, when temperatures were
raised by a strong cycle of El Niņo in the Pacific Ocean; 2002 and 2003 were
second and third warmest.
Dr. Hansen said a weak Niņo pattern was likely to make 2005 at least the
second warmest year and could push it beyond 1998 and set a record.
The unusual nature of the recent warming was corroborated separately
yesterday by a new analysis of 2,000 years of indirect temperature records
in tree rings, stalagmites, seabed layers, and other evidence from around
the Northern Hemisphere.
That study, published in the journal Nature, found that previous peaks of
warming, particularly during medieval times about 1,000 years ago, were as
warm as the 20th-century average but that no spikes in the last 2,000 years
matched the warming since 1990.
It is one of several recent studies challenging a longstanding view that
temperatures in the Northern Hemisphere were relatively unvarying until the
recent warming, a pattern enshrined in a graph scientists have taken to
calling the hockey stick for its long horizontal "shaft" and upward-hooking
The lead author of the new paper, Anders Moberg of Stockholm University in
Sweden, said it was important to recognize that natural influences on
climate could either amplify or mask human-caused warming in years to come.
But his paper "should not be a fuel for greenhouse skeptics in their
arguments," Mr. Moberg said, adding that there were ample signs that the
warming was now outside nature's recent bounds.