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Four years ago the Intergovernmental Panel on Climate Change (IPCC) concluded
that humans are at least partly responsible for global warming: "The balance
of evidence suggests a discernible human influence on global climate,"
IPCC said.[1] IPCC is an international group of 2500 meteorologists gathered
under the auspices of the United Nations, trying to figure out why the Earth
is warming up and what it might mean for human civilization.

The mechanism of warming is called the "greenhouse effect." Sunlight
streams in from outer space, strikes the surface of the planet, turns to heat
and then is radiated back out toward outer space. But some of the heat cannot
escape because it is reflected back to Earth by "greenhouse gases"
in the atmosphere. These "greenhouse gases" (water vapor, carbon dioxide
and methane) allow sunlight to pass through but they block heat, thus acting
like the glass roof on a greenhouse, producing warmth within.

The greenhouse effect is natural -- without it the Earth would be a frozen
rock spinning through space. But over the past few hundred years, humans have
contributed substantially to an increase in greenhouse gases. Burning coal,
oil and natural gas (so-called fossil fuels), plus deforestation, have increased
the atmospheric content of carbon dioxide by 31% (from 275 parts per million
[ppm] to 360 ppm) during the past few hundred years, a trend that continues
today. Fossil fuel combustion and deforestation now add about 7.7 billion tons
(7 billion metric tonnes) of carbon dioxide to the atmosphere each year. Other
human activities have increased the methane content of the atmosphere -- growing
cattle, growing rice, and landfilling garbage.

Since 1995, much new evidence has come to light indicating that the Earth is
indeed warming and that human activities are at least partly responsible. A
recent summary article by Bette Hileman in CHEMICAL & ENGINEERING NEWS,
voice of the American Chemical Society, describes some of the new evidence indicating
that the planet is warming at an accelerating pace:

** The Earth's average temperature has been rising for at least 100 years,
but in recent decades the rate of increase has speeded up. Eleven of the past
16 years have been the hottest of the century. The average global temperature
in 1998 was higher than it had been at any other time during the previous 1000

** The polar regions of the planet are heating up much more rapidly than the
average. Alaska is now as much as 10 degrees Fahrenheit (F.) (6 degrees Celsius
[C.]) warmer than it was 35 years ago. As the frozen north warms and thaws,
peat buried in the tundra decays, releasing carbon dioxide. This is a positive
feedback mechanism that could speed up the rate of increase of greenhouse gases
in the atmosphere -- the warmer the tundra becomes, the more carbon dioxide
it releases, in turn warming the tundra further. According to Walter C. Oechel,
director of the Global Change Research Group at San Diego State University (California),
the arctic tundra has been a sink (or storage place) for carbon for the last
9000 years, but since 1982 its role has reversed and now it has become a source
of carbon to the atmosphere.

Some far-northern (boreal) forests also seem to be shifting their role from
that of a carbon sink to a carbon source for the atmosphere as warmer temperatures
thaw frozen soils.[2] Whether the entire boreal forest belt, which encircles
the Earth, has become a net source of carbon remains unknown.

Bette Hileman does not say so, but the warming arctic tundra will likely also
release methane gas which, pound for pound, is about 20 times as powerful as
carbon dioxide at creating a greenhouse effect.[3] The quantity of carbon locked
in arctic soils is huge and the positive feedback loop that has begun to release
it to the atmosphere is ominous.

** Average summertime temperatures in Antarctica have risen 4.5 degrees F.
(2.5 degrees C.) since the 1940s. According to members of the British Antarctic
Survey, ice shelves along the coast of the Antarctic Peninsula have been breaking
up for 50 years, having lost 7000 square kilometers (2703 square miles) during
that time. The loss of 3000 square kilometers (1158 square miles) within just
the last year indicates that the breakup of ice shelves has accelerated.

The Greenland Ice Sheet, the world's second largest glacier, is growing thinner
at the rate of a meter (39 inches) per year. However, snowfall may be increasing
in polar regions, so no one is yet sure whether the overall amount of ice at
the poles is changing.

** The bleaching and loss of corals in the world's warm oceans (Indo-Pacific,
western Atlantic, and Caribbean) provide further evidence of accelerated global
warming. Corals are showing signs of stress in areas of human habitation and
in uninhabited regions. In uninhabited regions, the main causes are likely to
be increased ultraviolet light penetrating through the Earth's damaged ozone
shield, and global warming. Coral bleaching occurs when water temperatures rise,
and coral bleaching has been increasing worldwide since the 1970s as Earth's
temperature has risen most steeply.

Furthermore, recent work shows that, as the carbon dioxide content of the atmosphere
increases, so does the carbon dioxide content of ocean water. This in turn lowers
the concentration of carbonate ion, reducing the ability of corals to build
their skeletons.[4] The future for coral reefs looks grim.

Coral reefs are economically important -- they provide food, coastal protection,
and new medications for drug-resistant diseases. And they attract tourists by
the millions: Caribbean countries derive half their income from coral reefs.
The coral reefs of southeast Asia provide homes for one-quarter of the world's
fish species.

** Annual precipitation over the continental U.S. has increased about 10% during
this century, much of it during the winter, and much of it in heavy events.
For example, the number of days with rainfall exceeding 2 inches has increased
about 10% during the past century. Similar trends are observable in Canada,
Japan, Russia, China, and Australia.

Other consequences of global warming include:

** Moisture in the lower atmosphere has increased about 10% during the past
20 years.

** The annual number of intense storms over the North Atlantic and the North
Pacific has doubled since 1900.

** There have been more, and longer-lasting, El Nino events since the 1970s.
El Nino is a huge but localized warming in the eastern Pacific Ocean that gives
rise to violent storms along the U.S. Pacific coast, devastating droughts in
Africa and Australia, and often a failure of the monsoon rains in Asia.

** New computer models have been able to mimic past climate changes, and they
predict future warming of the atmosphere. Skeptics used to say that computer
models had done such a poor job of mimicking past events that their predictive
ability must also be flawed. That argument has been put to rest by better models
that track past events properly and which now predict an average global temperature
rise somewhere between 1.2 degrees C. (2.2 degrees F.) and 4 degrees C. (7.2
degrees F.) in the next century. Even a 1 degree C. (1.8 deg. F.) average temperature
rise could have important consequences because of exaggerated effects already
evident at the poles, though not all scientists agree with this assessment.

** Rather than diminish production of carbon dioxide, the U.S. government favors
a technical fix: U.S. global warming policy relies on the ability of forests
and agricultural soils to sop up excess carbon dioxide from the atmosphere.
A 1998 paper by U.S. government scientists seemed to show that North American
forests and soils were absorbing all of the carbon dioxide being emitted by
the burning of fossil fuels in North America.[5] Based on that study, the U.S.
demanded that forests-as-carbon -sinks be written into the Kyoto Treaty, an
international agreement intended to slow the production of greenhouse gases.
(See REHW #577.) At the meeting in Kyoto (Japan), the European Union remained
skeptical of the U.S. approach, but the U.S. threatened to walk out if its approach
was rejected. Now, according to Bette Hileman, two additional studies -- one
from France and the other from Australia -- have challenged the findings of
the original U.S. study, but these new studies remain unpublished and therefore
outside the debate.

This issue of forests as "sinks" for excess carbon has paralyzed
Kyoto Treaty negotiations since the Kyoto meeting because the issue is not fully
resolvable with present-day science and the U.S. continues to insist that its
viewpoint is defensible. Paralysis suits many U.S. leaders just fine -- key
members of Congress have indicated that the Kyoto Treaty will be ratified over
their dead bodies because they say the Kyoto Treaty will harm the U.S. economy.
But what if global warming will harm the economy for our children in the future?
Let the unborn speak now or forever hold their peace.

Independent U.S. scientists who have examined the ability of forests to absorb
carbon dioxide are not optimistic that the U.S. "sinks" plan has much
merit. Under ideal conditions, forests may be able to absorb as much as 50%
of excess carbon dioxide from the atmosphere, but to achieve that level of absorption
would require all trees to be young and all trees to be as responsive to carbon
dioxide as the most responsive, the loblolly pine. And of course when the trees
die, they will release the excess carbon back into the ecosystem. To prevent
global warming, trees would have to keep excess carbon out of the atmosphere

Cleaner sources of energy are already available and affordable. Adopting them
in the U.S. alone would create 770,000 jobs, save $530 per household per year,
and significantly reduce the threat of global warming.[6] Why can't we make
the shift? A recent report from the Natural Resources Defense Council (NRDC),
U.S. Public Interest Research Group, and the Union of Concerned Scientists points
out that 80% of greenhouse gases are produced by only 122 corporations,[7] which
act as "carbon pushers" comparable to drug pushers. The authors of
the report do not express it quite this way, but the conclusion is obvious:
these 122 corporations are jeopardizing the integrity of the entire global ecosystem,
endangering the future for all children, and holding the world's people and
their governments hostage by a combination of bribery and brute force. A simple
question: Why do we allow such antisocial -- even sociopathic -- behavior to
go unrewarded by prison sentences for culpable executives and boards of directors?
Please give it some thought.

--Peter Montague (National Writers Union, UAW Local 1981/AFL-CIO)


[1] Bette Hileman, "Case Grows for Climate Change," C&EN [CHEMICAL
& ENGINEERING NEWS] (August 9, 1999), pgs. 16-23.

[2] M. L. Goulden and others, "Sensitivity of Boreal Forest Carbon Balance
to Soil Thaw," SCIENCE Vol. 279 (January 9, 1998), pgs. 214-216.

[3] Jeff Hecht, "Shallow Methane Could Turn on the Heat," NEW SCIENTIST
(July 8, 1995), pg. 16. And: Jeff Hecht, "Baked Alaska," NEW SCIENTIST
(October 11, 1997), pg. 4. And: Fred Pearce, "Methane: The Hidden Greenhouse
Gas. Coming out of cattle, rubbish tips and rice fields, is warming the earth.
Yet methane from the Arctic could be the most damaging of all," NEW SCIENTIST
(May 6, 1989), pg. 37.

[4] Joan A. Kleypas and others, "Geochemical Consequences of Increased
Atmospheric Carbon Dioxide on Coral Reefs," SCIENCE Vol. 284 (April 2,
1999), pgs. 118-120.

[5] S. Fan and others, "A Large Terrestrial Carbon Sink in North America
Implied by Atmospheric and Oceanic Carbon Dioxide Data and Models," SCIENCE
Vol. 282 (October 16, 1998), pgs. 442-446.

D.C.: American Council for an Energy-Efficient Economy [1001 Connecticut Ave.,
NW, Suite 801, Washington, D.C. 20036; phone (202) 429-0063], June 1997. Available
for $25. See http://www.tellus.org/ei/eireport.html.

(New York: Natural Resources Defense Council and others, July 1999). Tel. (212)
727-1773. Available at: http:- file://www.nrdc.org/nrdcpro/fppubl.html .

Descriptor terms: global warming; greenhouse effect; fossil fuel; coral; precipitation
increases; tundra; forests; carbon sinks; carbon sources; methane gas; glaciers;

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  [Posted by Peter Montague on 12/2/2004]