From ABC News, 5/29/07:
http://abcnews.go.com/Technology/story?id=3223473&page=1

NASA: Danger Point Closer Than Thought From Warming

'Disastrous Effects' of Global Warming Tipping Points Near, According
to New Study

By BILL BLAKEMORE

Even "moderate additional" greenhouse emissions are likely to push
Earth past "critical tipping points" with "dangerous consequences for
the planet," according to research conducted by NASA and the Columbia
University Earth Institute.

With just 10 more years of "business as usual" emissions from the
burning of coal, oil and gas, says the NASA/Columbia paper, "it
becomes impractical" to avoid "disastrous effects."

The study appears in the journal Atmospheric Chemistry and Physics.

Its lead author is James Hansen, director of NASA's Goddard Institute
for Space Studies in New York.

The forecast effects include "increasingly rapid sea-level rise,
increased frequency of droughts and floods, and increased stress on
wildlife and plants due to rapidly shifting climate zones," according
to the NASA announcement.

Recent Climate Reports Underestimated How Soon

By heralding the new research paper, NASA is endorsing science that
places considerably more urgency on the need to reduce emissions to
avoid "disastrous effects" of global warming than was evident in the
recent reports from the world's scientists coordinated by the
Intergovernmental Panel on Climate Change.

The new NASA release emphasizes the danger of "strong amplifying
feedbacks" pushing Earth past "dangerous tipping points."

Scientists have been warning for several years that such tipping
points are the greatest threat from manmade global warming ÷ and what
makes it potentially catastrophic for civilization.

'Potentially Uncontrollable' Feedback Loops

As the tipping points pass, "there is an acceleration, potentially
uncontrollable, of emissions of vast natural stores of greenhouse
gas," according to Hansen, who reviewed the study for ABC News today.

Hansen explains that dangerous feedback loops are being tracked in
various regions of the planet.

Many studies have reported feedback loops already observed in thawing
tundra, seabeds and drying forests.

Hansen also points out that dark ÷ and therefore heat-absorbing ÷
forests are now expanding toward the Arctic, replacing lighter-colored
areas such as tundra and snow cover.

The NASA research also reasserts the importance of the disappearing
Arctic sea ice and snow, whose reflectivity has helped cool the planet
by bouncing warm sunlight straight back into space.

The disappearance of that bright sea ice and snow is uncovering more
and more dark water and bare ground ÷ creating another dangerous
feedback loop.

These feedbacks all produce more heat, thus all reinforcing each
other, leading to evermore thawing ÷ and thus releases of natural
greenhouse gases (including CO2 and methane) in a viciously
accelerating circle.

450 Parts Per Million

The recent IPCC summaries entertained "scenarios" of CO2
concentrations in the atmosphere ranging from 450 parts per million
(ppm) up through 550 ppm and 650 ppm.

This new research says "C02 exceeding 450 ppm is almost surely
dangerous."

Hansen told ABC News today he believes the upper limit for avoiding
dangerous climate change "could well be much lower" than 450 ppm.

In the NASA announcement, Hansen said, "'business as usual' emissions
would be a guarantee of global and regional disaster."

Earth's CO2 concentration is currently 383 ppm, up from 280 ppm at the
start of the industrial age.

Studies released earlier this month report human-made emissions now
spiraling upward at an accelerating rate much faster than scientists
expected only a few years ago.

The NASA release points out that a 1992 treaty was "signed (and
ratified) · by the United States and almost all nations of the world,"
which "has the goal to stabilize atmospheric greenhouse gases 'at a
level that prevents dangerous human-made interference with the climate
system.' "

NASA says this new study thus helps "define practical implications" of
that 1992 treaty ÷ the United Nations Framework Convention on Climate
Change.

The study says that "only moderate additional climate forcing (which
would mean only moderate additional warming from such emissions) is
likely to set in motion the disintegration of the West Antarctic ice
sheet" ÷ dubbed WAIS by polar scientists.

Many scientists say a disintegration of WAIS would mean
catastrophically rapid sea-level rise.

________________________________________________

The NASA/Columbia study is co-written by 48 scientists in the United
States and France.

Harry

From ABC News, 5/29/07:http://abcnews.go.com/Technology/story?id=3223473&page=1

NASA: Danger Point Closer Than Thought From Warming

'Disastrous Effects' of Global Warming Tipping Points Near, According
to New Study