Fwd: 1998 was Warmest Year of Millenium
kmorrisd at aol.com
Thu Mar 4 18:43:47 EST 1999
Some good research is being done at UMass. KMD
Activist Mailing List - http://users.westnet.gr/~cgian/
3 MARCH 1999
Contact: Harvey Leifert hleifert at agu.org 202-939-3212
American Geophysical Union
1998 Was Warmest Year Of Millenium, Climate Researchers Report
WASHINGTON, D.C. -- Researchers at the Universities of
Massachusetts and Arizona who study global warming have released
a report strongly suggesting that the 1990s were the warmest decade
of the millennium, with 1998 the warmest year so far. Researchers
have also found that the warming in the 20th century counters a
1,000-year-long cooling trend. The study, by Michael Mann and
Raymond Bradley of the University of Massachusetts and Malcolm
Hughes of the University of Arizona, appears in the March 15 issue
of Geophysical Research Letters, published by the American
Geophysical Union. The research was supported by the U.S.
Department of Energy and the National Science Foundation.
"Temperatures in the latter half of the 20th century were
The study involved a close examination of natural archives, such
as tree rings and ice cores, which record climate variations each
year. These natural archives are called "proxy indicators" by
scientists and allow researchers to consider the short instrumental
record of climate in a longer-term perspective. Using proxy
information gathered by scientists around the world during the past
few decades, the team used sophisticated computer analysis and
statistics to reconstruct yearly temperatures and their statistical
uncertainties, going back to the year AD 1000.
Specifically, they relied on three sets of 1,000-year-long
tree-ring records from North America, plus tree rings from northern
Scandinavia, northern Russia, Tasmania, Argentina, Morocco, and
France. Additionally, they studied ice cores from Greenland and the
"As you go back farther in time, the data become sketchier. One
can't quite pin things down as well," noted Mann, "but, our results
do reveal that significant changes have occurred, and temperatures
in the latter 20th century have been exceptionally warm compared
to the preceding 900 years. Though substantial uncertainties exist
in the estimates, these are nonetheless startling revelations."
Research published by the same team last year reconstructed yearly
global surface temperature patterns going back 600 years. That
study and the current report both relied on natural archives, and
determined that human-induced greenhouse gases were a major factor
in 20th century global warming.
The year 1998 was found to be the warmest year on record in
separate reports released by National Aeronautics and Space
Administration (NASA) and the National Oceanic and Atmospheric
Administration (NOAA). The reports were issued in January 1999,
reviewing climatic conditions for the previous year, but the
studies examined records only going back 120 years. The new study
puts the conclusions from NASA and NOAA in a much longer
According to the researchers, the 1,000-year reconstruction reveals
that temperatures dropped an average of 0.02 degrees Celsius per
century prior to the 20th century. This trend is consistent with
the "astronomical theory" of climate change, which considers the
effects of long-term changes in the nature of the Earth's orbit
relative to the Sun, which influence the distribution of solar
energy at the Earth's surface over many millennia.
"If temperatures change slowly, society and the environment have
time to adjust," said Mann. "The slow, moderate, long-term cooling
trend that we found makes the abrupt warming of the late 20th
century even more dramatic. The cooling trend of over 900 years was
dramatically reversed in less than a century. The abruptness of the
recent warming is key, and it is a potential cause for concern."
The latest reconstruction supports earlier theories that
temperatures in medieval times were relatively warm, but "even the
warmer intervals in the reconstruction pale in comparison with
mid-to-late 20th-century temperatures," said Hughes.
University of Massachusetts contact: Elizabeth Luciano --
413-545-2989 -- luciano at journ.umass.edu
University of Arizona contact: Lori Stiles -- 520-626-4402 --
lstiles at u.arizona.edu
For further information on the science in this paper, journalists
may contact: Raymond Bradley at 413-545-2120,
rbradley at geo.umass.edu (through March 5). Michael Mann at
413-545-9573, mann at geo.umass.edu (from March 4). Malcolm Hughes at
520-621-2191, mhughes at ltrr.arizona.edu .
An on-line press kit, including photos of the researchers,
graphics, and a link to the report, is available at:
http://www.umass.edu/newsoffice/press/99/0303climate.html . The
images will be at:
FAQ will be at:
Journalists and science public information officers (only) may also
obtain copies of the Mann et. al. paper upon request to Daryl Tate
dtate at agu.org . Please include your fax number.
Director, Climate Action NOW!
P.O. Box 324
Redway, CA 95560
can at asis.com
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