The Earth today stands in imminent peril
Pastor Dale Morgan
The Earth today stands in imminent peril
*
...and nothing short of a miraculous planetary rescue will save it from
the environmental cataclysm of dangerous climate change. Those are not
the words of eco-warriors but the considered opinion of a group of
eminent scientists writing in a peer-reviewed scientific journal.
By Steve Connor, Science Editor
Published: 19 June 2007
Six scientists from some of the leading scientific institutions in the
United States have issued what amounts to an unambiguous warning to the
world: civilisation itself is threatened by global warming.
They also implicitly criticise the UN's Intergovernmental Panel on
Climate Change (IPCC) for underestimating the scale of sea-level rises
this century as a result of melting glaciers and polar ice sheets.
Instead of sea levels rising by about 40 centimetres, as the IPCC
predicts in one of its computer forecasts, the true rise might be as
great as several metres by 2100. That is why, they say, planet Earth
today is in "imminent peril".
In a densely referenced scientific paper published in the Philosophical
Transactions of the Royal Society A some of the world's leading climate
researchers describe in detail why they believe that humanity can no
longer afford to ignore the "gravest threat" of climate change.
"Recent greenhouse gas emissions place the Earth perilously close to
dramatic climate change that could run out of control, with great
dangers for humans and other creatures," the scientists say. Only
intense efforts to curb man-made emissions of carbon dioxide emissions
and other greenhouse gases can keep the climate within or near the range
of the past one million years, they add.
The researchers were led by James Hansen, the director of Nasa's Goddard
Institute for Space Studies, who was the first scientist to warn the US
Congress about global warming.
The other scientists were Makiko Sato, Pushker Kharecha and Gary
Russell, also of the Goddard Institute, David Lea of the University of
California, Santa Barbara, and Mark Siddall of the Lamont-Doherty Earth
Observatory at Columbia University in New York.
In their 29-page paper, "Climate Change and trace gases", the scientists
frequently stray from the non-emotional language of science to emphasise
the scale of the problems and dangers posed by climate change.
In an email to The Independent, Dr Hansen said: "In my opinion, among
our papers this one probably does the best job of making clear that the
Earth is getting perilously close to climate changes that could run out
of our control."
The unnatural "forcing" of the climate as a result of man-made emissions
of carbon dioxide and other greenhouse gases threatens to generate a
"flip" in the climate that could "spark a cataclysm" in the massive ice
sheets of Antarctica and Greenland, the scientists write.
Dramatic flips in the climate have occurred in the past but none has
happened since the development of complex human societies and
civilisation, which are unlikely to survive the same sort of
environmental changes if they occurred now.
"Civilisation developed, and constructed extensive infrastructure,
during a period of unusual climate stability, the Holocene, now almost
12,000 years in duration. That period is about to end," the scientists
warn. Humanity cannot afford to burn the Earth's remaining underground
reserves of fossil fuel. "To do so would guarantee dramatic climate
change, yielding a different planet from the one on which civilisation
developed and for which extensive physical infrastructure has been
built," they say.
Dr Hansen said we have about 10 years to put into effect the draconian
measures needed to curb CO2 emissions quickly enough to avert a
dangerous rise in global temperature. Otherwise, the extra heat could
trigger the rapid melting of polar ice sheets, made far worse by the
"albedo flip" - when the sunlight reflected by white ice is suddenly
absorbed as ice melts to become the dark surface of open water.
The glaciers and ice sheets of Greenland in the northern hemisphere, and
the western Antarctic ice sheet in the south, both show signs of the
rapid changes predicted with rising temperatures. "
The albedo flip property of ice/water provides a trigger mechanism. If
the trigger mechanism is engaged long enough, multiple dynamical
feedbacks will cause ice sheet collapse," the scientists say. "We argue
that the required persistence for this trigger mechanism is at most a
century, probably less."
The latest assessment of the IPCC published earlier this year predicts
little or no contribution to 21st century sea level from Greenland or
Antarctica, but the six scientists dispute this interpretation. "The
IPCC analyses and projections do not well account for the nonlinear
physics of wet ice sheet disintegration, ice streams and eroding ice
shelves, nor are they consistent with the palaeoclimate evidence we have
presented for the absence of discernible lag between ice sheet forcing
and sea-level rise," the scientists say.
Their study looked back over more than 400,000 years of climate records
from deep ice cores and found evidence to suggest that rapid climate
change over a period of centuries, or even decades, have in the past
occurred once the world began to heat up and ice sheets started melting.
It is not possible to assess the dangerous level of man-made greenhouse
gases.
"However, it is much lower than has commonly been assumed. If we have
not already passed the dangerous level, the energy infrastructure in
place ensures that we will pass it within several decades," the
scientists say in their findings.
"We conclude that a feasible strategy for planetary rescue almost surely
requires a means of extracting [greenhouse gases] from the air."