Science warms to the cause -- Global Warming, Climate Change
From: Psalm 110 (Melchizedek_at_USA.com)
Date: 06/20/04
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Date: 19 Jun 2004 17:23:51 -0700
http://www.theaustralian.news.com.au/common/story_page/0,5744,9884327%255E30417,00.html
Science warms to the cause
If scientists disagree on the greenhouse effect, how do laymen find
the truth, asks science writer Leigh Dayton
June 19, 2004
IN 1990, the largest consortium of climate scientists ever gathered
delivered a clear, if not uniformly welcome, message. Global warming
was real and significant changes to Earth's climate were inevitable.
Three assessment reports down the track, the Intergovernmental Panel
on Climate Change -- established in 1988 by the UN Environment Program
and the World Meteorological Organisation -- went further. After
sifting, sorting and analysing all the scientific clues they could
gather, in their 2001 report the IPCC experts pointed the finger of
blame squarely at Homo sapiens.
"There is new and stronger evidence that most of the warming observed
over the past 50 years is attributable to human activities," they
concluded in the three-volume report, covering the science along with
the effects of the resulting climate change. The report also canvassed
steps that nations could take to reduce global warming and set out
information for decision-makers.
The climate-changing activities cited in the most recent report
include humanity's propensity to burn fossil fuels, clear land and
engage in intensive agriculture. Such practices release a host of
greenhouse gases into the atmosphere, particularly carbon dioxide,
methane and artificial chemicals called halocarbons.
The gases prevent heat from escaping into space, thereby turning up
the planet's average temperature and triggering a cascade of
atmospheric, meteorological and oceanographic changes. The result,
claim the scientists, will be extensive destabilisation of Earth's
climate system.
Referring to the report, UNEP executive director Klaus Topfer wrote:
"[It] presents a compelling snapshot of what the Earth will probably
look like in the late 21st century, when a global warming of 1.4C to
5.8C will influence weather patterns, water resources, the cycling of
the seasons, ecosystems, extreme climate events and much more. Even
greater changes are expected in the more distant future."
Although, as Topfer notes, the IPCC process engages hundreds of the
world's leading experts in reviewing the most up-to-date,
peer-reviewed literature on the scientific and technical aspects of
climate change, it is not without detractors.
Early critics, such as meteorologist Richard Lindzen of the
Massachusetts Institute of Technology, pointed to disagreement between
computer simulations of future climate. If scientists couldn't agree
on details, their findings should be discounted, the argument ran.
Such reasoning has, and continues, to miss the point, counter IPCC
participants, including Penny Whetton, a climatologist with the CSIRO
atmospheric research division in Melbourne. All three reports have
clearly outlined the nature and magnitude of uncertainty and sketch
alternative futures based on scientific knowns and unknowns, as well
as developments in areas such as technology, government action and
population growth.
Whetton says the nature of criticism has shifted. "We hear less than
we did a few years ago that the science is all wrong and climate
change isn't happening," she says. "The critics seem to accept global
warming much better."
Today, critics such as self-proclaimed environmental sceptic and
statistician Bjorn Lomborg focus on the magnitude of expected change
and the social and economic value of countering change. Additionally,
a small group of geologists claim the IPCC has ignored the geological
record.
For instance, the University of Melbourne's Ian Plimer and Bob Carter
of James Cook University and the University of Adelaide have argued in
The Australian that cores drilled deep into the ocean, the Antarctic
and Greenland show that climate change occurred repeatedly in the
geological past. According to Whetton, this is exactly the sort of
data that will be included in the next assessment report, which is
just getting under way. "But just because there have been changes in
the geological past, that doesn't make it any easier for us to deal
with now and it [didn't happen] with 6 billion people on the planet,"
she says.
A goal of the fourth assessment, due in 2007, will be to tighten up
regional climate change forecasts and the rates of predicted change,
areas of the greatest uncertainty. At least eight Australian experts,
including Whetton, have signed on to the IPCC team.
Meanwhile, observations cited in the third IPCC report suggest that
global climate is indeed changing. Some examples are that the warmest
decade of the millennium was the 1990s and 1998 the warmest year; the
mean sea level rose 10cm to 20cm; snow cover in the northern
hemisphere declined about 10 per cent since the late '60s; rainfall
increased from 0.5 per cent to 1 per cent per decade during the 20th
century; the concentration of carbon dioxide increased by about 30 per
cent over pre-industrial levels; and recent El Ninos are more intense,
frequent and persistent than those of 100 years ago.
Despite more and better science, one enormous climate change
uncertainty remains: what -- if anything -- humanity will do about it.
Not even the best and biggest scientific panel can predict that
outcome with 100 per cent certainty.
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