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Date: Thu, 4 Mar 1999 13:27:43 EST
From: C
Subject: GL: UCAR News-Indian Ocean
----------------------------Original message----------------------------
1999-6
March 4, 1999
Contact:
Anatta
UCAR Communications
Telephone: 303-497-8604
E-mail: anatta@ucar.edu
NCAR Scientists, Aircraft, Instruments Head to Indian Ocean
for Climate Change Experiment; UCAR Directs Operations
BOULDER--How much do sulfate aerosols--a form of pollution--cool the
climate? That's one of the most pressing questions for understanding
global climate change. To help find the answer, the National Center for
Atmospheric Research (NCAR) has sent researchers, instruments, and a C-
130 research aircraft owned by the National Science Foundation (NSF) to
the $25-million Indian Ocean Experiment (INDOEX). NSF is NCAR's primary
sponsor and a partial sponsor of INDOEX.
INDOEX is based in the Republic of the Maldives, an archipelago
southwest of India's southern tip. There, NCAR scientists are working
alongside more than 70 researchers from a dozen nations to observe the
tropical oceans and atmosphere from January to April. The University
Corporation for Atmospheric Research, NCAR's parent organization, is
overseeing operations from its support office for logistics and data
management, headed by Richard Dirks of the UCAR Office of Programs. The
highly instrumented C-130 aircraft will be based through March 27 at
Mal=E9 airport, which occupies its own island in the archipelago.
According to NCAR's Jeffrey Kiehl, a principal investigator for INDOEX,
"In the future, pollution in the tropics will increase, so we'd better
understand it now. The chemistry in the tropics is severely
undersampled." The Indian subcontinent and surrounding nations are rich
sources for many kinds of aerosols, including those produced from
industrial and auto emissions, biomass burning, and soil dust. With
Asia's population rising at a dramatic rate, the amount of sulfur
dioxide released into the atmosphere is expected to increase. Sulfur
dioxide is converted into sulfate aerosol in the atmosphere.
The ability of sulfate aerosols to reflect the sun's radiation may be
one reason that increasing greenhouse gases have not warmed the earth as
much as some climate models have predicted. Sulfates also contribute to
local pollution and acid rain.
Kiehl helped design INDOEX to ensure that the project collects the data
needed to advance global climate modeling. Some physical and chemical
processes in the earth system are so complicated that modelers cannot
simulate each detailed step. "With INDOEX data, we can actually test the
way we treat aerosols in computer models against observations."
The observation region is downwind of the Indian subcontinent during the
spring and extends into the pristine Southern Hemisphere. With a
forecast of pleasant weather--calm, with little rain--the investigators
should be able to sample both polluted and clean air in clouds and clear
sky.
"It's a natural laboratory for studying direct and indirect effects of
aerosols," says NCAR's Andrew Heymsfield, another INDOEX researcher. The
direct effect of aerosols is the scattering that occurs when solar
radiation bounces off particles in clear air. The indirect effects have
to do with sulfates' interactions with clouds.
Globally, aerosols are an important source of nuclei around which cloud
droplets can condense, and in the tropics they are the chief source. The
more cloud condensation nuclei, the brighter the cloud, that is, the
more solar radiation reflected back into space before it reaches the
earth's surface. This radiative effect is what makes clouds, and the
indirect effects of aerosols, so important in climate change research.
However, indirect effects are now so little understood that estimates in
global climate models vary from almost no effect to more than enough
cooling to offset global warming resulting from greenhouse gas
increases.
"A host of changes in cloud physical and microphysical properties are
lumped under the term 'indirect effects,' " says NCAR scientist William
Collins. Collins is using satellite measurements to estimate optical
depths in clouds and the sizes of aerosol droplets.
The Maldives archipelago runs in a north-south line from about 500 miles
southwest of the tip of the Indian subcontinent to the equator. The
personnel and observing systems are spread across several islands, with
all transport by boat. Resources include five aircraft, two research
ships, and a host of ground-based systems. Satellite data will be used
for real-time weather forecasting, monitoring the motion of pollutants,
and measuring radiation at different altitudes. This combination of
ground, airborne, and satellite data is expected to vastly increase
scientists' understanding of the nature and scope of aerosols' indirect
effects.
Heymsfield and NCAR colleague Gregory McFarquhar are studying some of
the cloud microphysical changes using a scanning aerosol backscatter
lidar, developed at NCAR and mounted on the C-130. From the aircraft the
lidar can characterize cloud top and bottom. The scientists will observe
the optical depth of clouds in both clear and cloudy aerosol-laden
skies.
"The government of the Maldives has been extraordinarily cooperative and
accommodating," says Dirks. "They're deeply concerned with climate
change research." The Maldives islands are vulnerable to rising sea
levels due to climate change.
INDOEX is coordinated by the Center for Clouds, Chemistry and Climate
(C4), an NSF Science and Technology Center at the Scripps Institution of
Oceanography. Paul J. Crutzen, director of the Max Planck Institute for
Chemistry and a 1995 Nobel Laureate in Chemistry, and C4 director V.
Ramanathan will serve as INDOEX chief scientists.
-The End-
Note to Editors: Please contact Anatta (information above) to
interview INDOEX participants or to fly on the C-130 aircraft.
For more information, see the INDOEX Web site: http://www-indoex.ucsd.edu=tm.htmltmlmd/index.htmll
/
------------------------------
Date: Thu, 4 Mar 1999 14:09:37 EST
From: C
Subject: GL: 1990's Warmest Decade of Millenium, Climate Researchers Report
3 MARCH 1999
Contact: Harvey Leifert hleifert@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
unprecedented,"said Bradley.
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
Andes mountains.
"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
perspective.
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.
###
http://www.eurekalert.org/releases/agu-nww030399.html
Notes:
University of Massachusetts contact: Elizabeth Luciano --
413-545-2989 -- luciano@journ.umass.edu
University of Arizona contact: Lori Stiles -- 520-626-4402 --
lstiles@u.arizona.edu
For further information on the science in this paper, journalists
may contact: Raymond Bradley at 413-545-2120,
rbradley@geo.umass.edu (through March 5). Michael Mann at
413-545-9573, mann@geo.umass.edu (from March 4). Malcolm Hughes at
520-621-2191, mhughes@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:
http://www.umass.edu/newsoffice/press/99/0303climateimages.html .
FAQ will be at:
http://www.umass.edu/newsoffice/press/99/0303climatefaq.htmltml .
Journalists and science public information officers (only) may also
obtain copies of the Mann et. al. paper upon request to Daryl Tate
dtate@agu.org . Please include your fax number.