FW: Global warming, was RE: marxism-digest V1 #5242 #2
markjones011 at tiscali.co.uk
Mon Dec 9 08:22:03 MST 2002
(12/04/1995) Scientists confirm anthropogenic greenhouse gases as cause of
global warming trend, worry positive feedback processes could lead to
"runaway" global warming. The contents of the premier scientific journals in
the months immediately following the Berlin Climate Summit in April 1995
reveal a pronounced decrease in the level of uncertainty top climate-change
researchers were prepared to ascribe to the view that the warming in recent
decades might be due to reasons other than greenhouse warming. On April 7,
1995, a researcher from AT&T's Bell Labs published a statistical treatment
of the twentieth-century warming record showing correspondence between
warming and a decreasing amplitude of the annual temperature cycle - the
temperature difference between winter and summer. Had changes in incoming
solar radiation been solely or largely responsible for observed warming, as
greenhouse skeptics tend to argue, the reverse should have been the case.
Solar variability, AT&T researcher David Thomson concluded, "is at most a
minor factor." Thomson said "you almost have to invoke magic if it is not
carbon dioxide. It's the only logical explanation."
On April 21, 1995, scientists at the US National Climatic Data Center
reported they had found a pattern suggesting that the US climate has turned
towards a greenhouse regime in the last 15 years. They compiled data on
climatic extremes expected to arise under greenhouse warming, including
higher-than-normal daily minimum temperatures, extreme or severe droughts in
warm months, and much-above-normal precipitation in cool months. Using this
data, they calculated a Greenhouse Climate Response Index in order to
express any persistent trends. The index has been consistently high since
the late 1970s, in marked contrast to the pattern in earlier decades. Thomas
Karl, the lead researcher, concluded that the probability that this can be
natural fluctuation in a stable climate is only about 5%.
In June 1995 came two other high-powered studies similarly dismissive of
natural climatic variability as an explanation for the hot years of the
1980s and 1990s, this time in the global record. A team from Germany's
leading climate lab, the Max Planck Institute for Meteorology, concluded
that there is only one chance in forty that natural variability can explain
the warming seen over the last 30 years. "At the moment there is no other
convincing explanation than carbon dioxide for such a big change in
temperature," a member of the German team, Gabriele Hegerl, reported.
A second team at the USA's Lawrence Livermore Laboratory factored the
cooling influence of sulphate aerosols (largely derived from coal burning)
into the temperature record, leaving a clear greenhouse fingerprint since
about 1950, when the growth of carbon dioxide emissions took off. Commenting
on this in Science magazine, Thomas Karl said "you're seeing a shift in the
overall scientific view".
Then, on August 10, 1995, the results of the most sophisticated
climate-model experiments yet performed were reported in Nature magazine.
Researchers at the UK's Meteorological Office effectively simulated past
climate variations using a coupled model (one linking both the atmospheric
and oceanic components of the climate system) which also factored in the
sulphate aerosol effect. This breakthrough significantly boosted confidence
in the accuracy of the models used for forecasting climate change in the
future. Leading IPCC climatologist Tom Wigley wrote in a commentary that
"these results mark a turning point both in our ability to understand past
changes and predict the future".
The impression of a significant stiffening of scientific opinion on the
question of "the signal" was reinforced at a conference of leading
climatologists in Colorado, reported in Nature on August 24, 1995.
Rapporteur Michael MacCracken, summarizing many presentations, concluded
that the evidence for an anthropogenic signal was becoming "quite
compelling. Although greenhouse gases and aerosols are not yet convicted
beyond all reasonable doubt (in the warming of recent decades), the case is
becoming steadily stronger".
And at the same time, the drip of worrying evidence that the feedbacks may
be preparing to kick in, stoking up an amplifying effect for future warming,
did not abate. In Science magazine on August 25, 1995, a team of researchers
at the US National Oceanographic and Atmospheric Administration reported
that they had found isotopic evidence for a large sink for carbon dioxide on
land in the northern hemisphere during 1992 and 1993. "Because carbon
storage on land is likely to be more transient and vulnerable to
anthropogenic and climatic perturbations than storage in the oceans," they
concluded, "the current partitioning of CO2 uptake between the oceans and
the land biosphere may well have significant implications for future
increases in atmospheric CO2".
Within a week, as though to abate hopes that even the oceanic sink would
hold up, came evidence in Nature magazine that the oceans may be losing
fixed nitrogen. Fixed nitrogen, as the nutrient nitrate, is a major control
on the abundance of phytoplankton. Denitrification - the degradation of
nitrate by bacteria in areas of oxygen-deficient surface waters in the
oceans - converts fixed nitrogen to free nitrogen or nitrous oxide, of no
use to most plants. Studying nitrogen balances, Canadian and American
oceanographers found evidence that warmer oceans will lose nitrate, thereby
depleting phytoplankton, which will in turn increase the amount of
atmospheric carbon dioxide.
On September 10, 1995, the stiffening of scientific opinion reached the
front page of the New York Times. The headline referred to a leaked draft
copy of the IPCC's Second Assessment report, due to be published in
December. It read: "Experts confirm human role on global warming."
Against the march of this kind of evidence and events, soon to be codified
in the IPCC Second Assessment, the arguments of the small but vocal
community of so-called "global warming skeptics" are beginning to look
increasingly flimsy. (Sources)
(09/01/1990) Geologists fear Arctic warming could lead to release of vast
amounts of methane hydrates, leading to runaway global warming. One
explanation of rapid climate change at the end of the last glaciation,
argues Dr. Euan Nisbet of the University of Sakatchewan, is that it was
initially driven by methane released from natural gas fields and gas
hydrates during a period of extreme insolation. Methane is an even more
potent greenhouse gas than carbon dioxide.
Methane hydrates are solids which lock methane gas up under pressure in an
ice-like lattice of water molecules. They are present under the oceans and
permafrost in vast quantities. In the offshore Arctic, the cold allows their
formation at sufficiently shallow depths that warming can reach them and
Nisbet is one of a number of geologists who fear methane hydrates as a
potentially major positive feedback mechanism that could be released by
global warming. He wrote in a 1989 paper that "any slight warming of the
Arctic water will release hydrate from the sea floor almost immediately. A
temperature change of a few degrees will liberate methane from the uppermost
sea-floor sediments at this depth within a few years."
The worst-case analysis is grim indeed: "the danger of a thermal runaway
caused by methane release from permafrost is minor, but real ... even if
there is only a 1 per cent chance that such events will occur, the social
implications are profound," says Nisbet. (Sources)
(10/29/1999) In research with potentially critical implications for current
climate change study, scientists find that a catastrophic release of methane
hydrate deposits due to warming oceans led to melting of the polar ice caps
during the Cenozoic era and the mass extinction of species. Fifty-five
million years ago, during the Cenozoic era, geologic evidence shows that
Earth's polar ice caps did not exist. They had melted because the Earth was
on average 4 to 6 degrees Celsius warmer than it is today, and temperatures
at the poles may have been two times or more warmer than the global average
at the time. But climatologists have had difficulty explaining that fact
using models that rely solely on the effects of greenhouse gases. Now new
research presented at the 1999 meeting of the Geological Society of America
points to methane gas as a possible reason why the paleoclimate in the
Cenozoic era was so warm.
Lisa Sloan, an Earth scientist at the University of California at Santa Cruz
(UCSC), said new climate models she and her colleagues have generated
indicate that the indirect effects of high concentrations of methane gas in
the atmosphere probably played a major role in warming the Earth,
particularly the polar regions.
An overly warm ocean triggered the methane release. When the ocean reached a
certain temperature, a critical threshold was crossed that allowed a
catastrophic release of methane hydrates in the sea floor.
The released methane, a byproduct of abundant bacteria thriving on an
already warm and wet Earth between 50 and 60 million years ago, in turn
produced stratospheric clouds of water vapor that can only form in the
shadowy polar regions. This held in solar heat, warmed and melted ice at the
poles and, in turn, warmed the Earth, Sloan said.
The 150,000-year-long epoch of climate warming during the Cenozoic era had
profound effects on countless marine and terrestrial organisms, including
the mass extinction of species, according to research by William C. Clyde of
the Department of Earth Sciences at the University of New Hampshire.
(06/28/1999) Scientist calls unprecedented appearance of noctilucent clouds
over Colorado and Utah a global warming "canary in the coal mine." A
luminescent meteorological phenomenon rarely seen in the contiguous United
States, noctilucent clouds, has made a surprise visit recently and one
expert says increased carbon dioxide may be to blame. Noctilucent clouds are
usually seen only in the far northern and southern latitudes. Occurring
about 52 miles (85 kilometers) above the Earth, in the upper atmosphere,
they are so high that they reflect the sun's rays even at night.
Scientists have had trouble explaining the clouds' existence over Colorado
and Utah, but at least one researcher believes he may now have the key. Gary
Thomas, a professor at the University of Colorado at Boulder's Laboratory
for Atmospheric and Space Physics, is an expert on noctilucent clouds. The
recent appearance came as quite a surprise to him. "I had predicted [in
1994] that we wouldn't see noctilucent clouds [south of] the latitude of 40
degrees until the 21st century. I guess I was wrong on that one." Most of
the U.S.-Canadian border lies at 49 degrees latitude.
Thomas believes that the clouds form as methane gas rises unimpeded through
the natural cold trap, an area of very cold temperatures about nine miles
(15 kilometers) above the Earth. The rising methane may react with sunlight
to form large quantities of water vapor that eventually freeze and circulate
to the top of the atmosphere.
Thomas believes that noctilucent cloud formation is being hastened by
increased amounts of carbon dioxide (CO2) in the Earth's atmosphere. While
carbon dioxide is thought to contribute to global warming in the lower
atmosphere, it has the opposite affect on the middle and upper atmospheres,
where it causes cooling, he said. "This could be a natural cycle that we
don't understand, it could be a fluke or a freak, but it's my opinion that
increased CO2 is playing a major role in this. It is just something we don't
know much about and requires more study."
The mesosphere, located between 31 and 56 miles (50 and 90 kilometers) above
the Earth, right above the stratosphere, has been cooling by as much as one
degree Celsius every year for the past 30 years, according to an article in
New Scientist. That is ten times faster than anyone had predicted, said
Thomas. "What we're seeing are some dramatic (upper atmospheric cooling)
effects that are far greater than what the models are predicting," he said.
For Thomas, the cooling of the mesosphere is the canary in the coal mine. It
is the most recent, biggest, and most unequivocal signal that the global
climate really is changing, he says. "This is a big event," said Thomas.
"While they are a beautiful phenomenon, these clouds may be a message from
Mother Nature that we are upsetting the equilibrium of the atmosphere."
The first sighting of noctilucent clouds from the continental United States
was on July 1, 1993, by Jay Brausch, an amateur sky watcher in Glenn Ullen,
North Dakota. The recent sighting was reported by Richard Keen, a
meteorology instructor at the University of Colorado at Boulder, and Mike
Taylor, a physics professor at Utah State University. Keen's was the most
southerly sighting of noctilucent clouds in the contiguous United States. "I
saw silvery clouds to the northwest that were distinctly brighter and higher
than the other clouds," he said. "My first thought was: It can't be. But I'd
seen them before in Alaska, so I know what they look like. They have a
distinctive color and features [they are silvery blue and form bands]."
(09/30/2000) World famous physicist Stephen Hawking says he's worried
runaway global warming could could destroy human life on Earth. World
renowned physicist Stephen Hawking fears the human race may not survive
another millennium. "I am afraid the atmosphere might get hotter and hotter
until it will be like Venus with boiling sulfuric acid," the physicist said.
"I am worried about the greenhouse effect."
To ensure the survival of humans, he adds, efforts must be made to colonize
other planets. Space travel would not solve every problem, but at least it
would ensure that people don't become extinct. "It takes too many resources
to send each person into space," he said. "But unless the human race spreads
into space, I doubt it will survive the next thousand years."
Hawking, 58, holds the Cambridge University post once held by Sir Isaac
Newton and is the author of the best-selling "A Brief History of Time."
(NOTE: Original news source(s) will open in a new window. Links were good on
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(09/30/2000) Nando Times: Hawking says greenhouse effect threatens human
(10/29/1999) Nando Times: Methane Gas Research Could Help Scientists
Understand Global Warming.
(07/19/99) San Francisco Examiner: Warning of more global warming.
(06/28/1999) National Geographic: Glow-in-the-Dark Clouds: A Global Warning?
(12/04/1995) Center for Environmental Information/U.S. Global Change
Research Program: An Environmentalist's Perspective on the Current State of
the Climate Debate.
(06/01/1992) Bulletin of Atomic Scientists: Global warming: The worst case.
(09/01/1990) Greenpeace Climate News Database: Methane hydrates could
strongly amplify global warming.
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