Hans Joachim Schellnhuber, the director of the Potsdam
Institute for Climate Impact Research in Germany, says that if the
buildup of greenhouse gases and its consequences pushed global
temperatures 9 degrees Fahrenheit higher than today — well below the
upper temperature range that scientists project could occur from global
warming — Earth's population would be devastated.
"In a very cynical way, it's a triumph for science because at last
we have stabilized something –- namely the estimates for the carrying
capacity of the planet, namely below 1 billion people.”
Schellenhuber’s comments at the COP 15 Copenhagen Conference on Climate Change underscore that, given high rates of observed
emissions, the worst-case IPCC scenario trajectories are unfolding. For many key parameters, the climate system is
already moving beyond the patterns of natural variability within which
our society and economy have developed and thrived. These parameters
include global mean surface temperature, sea-level rise, ocean and ice
sheet dynamics, ocean acidification, and extreme climatic events. There
is a significant risk that many of the trends will accelerate, leading
to an increasing risk of abrupt or irreversible climatic shifts.
Recent observations show
that societies are highly vulnerable to even modest levels of climate
change, with poor nations and communities particularly at risk.
Temperature rises above 2°C will be very difficult for contemporary
societies to cope with, and will increase the level of climate
disruption through the rest of the century.
It is important for people to understand that the warming the IPCC
talks about is not hypothetical. Eleven of the last 12 years
(1995-2006) rank among the warmest years in global surface temperature
since 1850. Glaciers and snow cover have declined, and ice sheets from
Greenland and parts of Antarctica are melting. The ocean has been
absorbing more than 80% of the heat added to the climate system, yet
the average temperature of the ocean has increased up to a depth of
3,000 meters, causing seawater to expand and contributing to sea level
rise.
Schellnhuber, citing his own research, said that at certain "tipping
points," higher temperatures could cause areas of the ocean to become
deoxygenated, resulting in what he calls "oxygen holes" between 600 and
2,400 feet deep. These are areas so depleted of the gas that they would
badly disrupt the food chain.
Unabated warming would also lead to "disruption of the monsoon,
collapse of the Amazon rain forest and the Greenland ice sheet will
meltdown," he said.
Scientists must make clear the disastrous effects of climate change so
the world takes action now to cut carbon emissions, leading economist
Nicholas Stern said on told the gathering of
2,000 scientists.
“You have to tell people very clearly and strongly just how difficult
(a temperature rise of) four, five, six or seven degrees Celsius is,”
he said.
“Billions of people would have to move and there would be very severe
conflict,” said Stern, a professor at the London School of Economics
and a former British Treasury economist.
“That’s a story that must be told to persuade people it’s a very bad
idea to go anywhere near five degrees. This is not a black swan, this
is a big probability of a devastating outcome,” he
Posted by Casey Kazan
Sources:
http://dotearth.blogs.nytimes.com/2009/03/13/scientist-warming-could-cut-population-to-1-billion/
http://www-ramanathan.ucsd.edu/dai/Schellnhuber-PNAS-2008.pdf
http://www.copenhagenclimatecouncil.com/get-informed/news/scientists-deliver-politicians-key-messages-for-copenhagen-climate-talks.html
http://www.copenhagenclimatecouncil.com/get-informed/news/clear-and-present-danger-a-conversation-with-nobel-laureate-steve-chu-on-the-risks-of-climate-change.html
http://in.reuters.com/article/environmentNews/idINTRE52B37Q20090312?pageNumber=2&virtualBrandChannel=0
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