EEE会議（地球温暖化と人間活動の関係：米国科学者の最新報告）..........................................031206


ブッシュ政権は、あるいはブッシュ大統領自身は、地球温暖化と人間活動は無関係と
の立場に立っているようですが、最近発表された米国政府機関の責任ある科学者たち
（Dr. Thomas Karl, director of NOAA's National Climatic Data
Center, and Dr. Kevin Trenberth, head of the Climate Analysis Section at the
National Center for Atmospheric Research (NCAR)の研究報告によれば、「人間活
動が地球温暖化に影響を与えていることはもや疑問の余地がない」ということで、例
えば、1990〜2100　の期間に、地球の温度が1.7 〜 4.9 度Ｃ上昇する確率は 90 ％
あるということです。
その結果南北極、グリーンランド等の氷や氷河が溶けて地球が水浸しになり、うんう
ん。　これは、今まで何度も聞かされてきたことで今更という気がしますが、ブッ
シュ政権下の米国政府機関の研究者による最新の研究成果として注目に値すると思い
ます。　詳細は次の国務省発表（在日米国大使館提供）でどうぞ。
--KK

*******************************************

Text: No Doubt of Human Impact on Global Climate, Scientists Say

(Industrial emissions are dominant influence on climate change, research
shows)

Two U.S. atmospheric scientists, citing atmospheric observations and
computer model experiments by climate scientists, say there is no longer
any doubt that human activities are having measurable -- and increasing --
impacts on global climate.

A December 2 press release from the National Center for Atmospheric
Research (NCAR) says their study, which appears in the December 5 issue of
the journal Science, paints a detailed picture of climate changes likely
to buffet Earth in coming decades, including rising temperatures and an
increase in extreme weather events such as flooding and drought.

"There is no doubt that the composition of the atmosphere is changing
because of human activities, and today greenhouse gases are the largest
human influence on global climate," write Thomas Karl, director of the
National Oceanic and Atmospheric Administration's National Climatic Data
Center, and Kevin Trenberth, head of the Climate Analysis Section at NCAR.

The scientists conclude that industrial emissions have been the dominant
influence on climate change for the past 50 years, overwhelming natural
forces. Levels of carbon dioxide, a major greenhouse gas that traps solar
radiation and warms the planet, have risen by 31 percent since
pre-industrial times -- from 280 parts per million by volume (ppmv) to
over 370 ppmv today.

Other human activities, such as emissions of sulfate and soot particles
and the development of urban areas, have significant but more localized
climate impacts, the authors report.

They estimate that, between 1990 and 2100, there is a 90 percent
probability that global temperatures will rise by 1.7 to 4.9 degrees
Celsius. Such warming would have widespread impacts on society and the
environment, including continued melting of glaciers and the great ice
sheets of Greenland, inundating the world's coasts.

Karl and Trenberth say more research is needed to pin down both the global
and regional impacts of climate change. This, in turn, will require
considerable international cooperation and the establishment of a global
climate monitoring system to collect and analyze data.

Following is the text of the press release:

(begin text)

National Center for Atmospheric Research
December 2, 2003

"No Doubt" Human Activity Is Affecting Global Climate, Top Scientists
Conclude

BOULDER   Two of the nation's premier atmospheric scientists, after
reviewing extensive research by their colleagues, say there is no longer
any doubt that human activities are having measurable and
increasing impacts on global climate. Their study cites atmospheric
observations and multiple computer models to paint a detailed picture of
climate changes likely to buffet Earth in coming decades, including rising
temperatures and an increase in extreme weather events, such as flooding
and drought. The study appears December 5 in Science as part of the
journal's "State of the Planet" series.

The coauthors--Thomas Karl, director of NOAA's National Climatic Data
Center, and Kevin Trenberth, head of the Climate Analysis Section at the
National Center for Atmospheric Research (NCAR)--conclude that industrial
emissions have been the dominant influence on climate change for the past
50 years, overwhelming natural forces. The most important of these
emissions is carbon dioxide, a greenhouse gas that traps solar radiation
and warms the planet.

"There is no doubt that the composition of the atmosphere is changing
because of human activities, and today greenhouse gases are the largest
human influence on global climate," they write. "The likely result is more
frequent heat waves, droughts, extreme precipitation events, and related
impacts, e.g., wildfires, heat stress, vegetation changes, and sea-level
rise which will be regionally dependent."

The article cites research indicating that, between 1990 and 2100, there
is a 90 percent probability that global temperatures will rise by 1.7 to
4.9 degrees Celsius (3.1 to 8.9 degrees Fahrenheit), because of human
influences on climate. Such warming would have widespread impacts on
society and the environment, including continued melting of glaciers and
the great ice sheets of Greenland, inundating the world's coasts. The
authors base their estimate on computer model experiments by climate
scientists, observations of atmospheric changes, and recorded climate
changes over the past century.

However, there is still large uncertainty in understanding the global
climate and how it will change, says Karl. If temperatures rise 1.7
degrees, the expected changes would be relatively small, whereas a
4.9-degree increase could bring drastic impacts, some of which may be
unforeseen.

Carbon dioxide levels in the atmosphere have risen by 31 percent since
pre-industrial times, from 280 parts per million by volume (ppmv) to over
370 ppmv today. Other human activities, such as emissions of sulfate and
soot particles and the development of urban areas, have significant but
more localized climate impacts. Such activities may enhance or mask the
larger-scale warming from greenhouse gases, but not offset it, according
to the authors.

If societies could successfully cut emissions and stabilize carbon dioxide
levels in the atmosphere, temperatures would still increase by an
estimated 0.5 degree C (0.9 degree F) over a period of decades, Karl and
Trenberth warn. This is because greenhouse gases are slow to cycle out of
the atmosphere. "Given what has happened to date and is projected in the
future, significant further climate change is guaranteed," the authors
state.

If current emissions continue, the world would face the fastest rate of
climate change in at least the last 10,000 years. This could potentially
alter ocean current circulations and radically change existing climate
patterns. Moreover, certain natural processes would tend to accelerate the
warming. For example, as snow cover melts away, the darker land and water
surface would absorb more solar radiation, further increasing
temperatures.

Karl and Trenberth say more research is needed to pin down both the global
and regional impacts of climate change. Scientists, for example, have yet
to determine the temperature impacts of increased cloud cover or how
changes in the atmosphere will influence El Ni�o, the periodic warming of
Pacific Ocean waters that affects weather patterns throughout much of the
world. The authors call for multiple computer model studies to address the
complex aspects of weather and climate. The models must be able to
integrate all components of Earth's climate system用hysical, chemical, and
biological. This, in turn, will require considerable international
cooperation and the establishment of a global climate monitoring system to
collect and analyze data.

Because of the broad range of potential change in temperature, it's
extremely important to ensure that we have a comprehensive observing
system to track unforeseen changes and variations, says Karl.

"Climate change is truly a global issue, one that may prove to be
humanity's greatest challenge," the authors conclude. "It is very unlikely
to be adequately addressed without greatly improved international
cooperation and action."

(end text)

(Distributed by the Bureau of International Information Programs, U.S.
Department of State. Web site: http://usinfo.state.gov)
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