- NEW YORK (AP) -- Climate
scientists armed with new data from the ocean depths and from space satellites
have found that Earth is absorbing much more heat than it is giving off,
which they say validates computer projections of global warming.
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- Lead scientist James Hansen, a prominent NASA climatologist,
described the findings on the planet's out-of-balance energy exchange as
a "smoking gun" that should dispel doubts about forecasts of
climate change. A European climate expert called it a valuable contribution
to climate research.
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- Mr. Hansen's team, reporting Thursday in the journal
Science, said they also determined that global temperatures will rise 0.6
degrees Celsius this century even if greenhouse gases are capped tomorrow.
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- If carbon dioxide and other heat-trapping emissions instead
continue to grow, as expected, things could spin "out of our control,"
especially as ocean levels rise from melting Greenland and Antarctic ice
sheets, the researchers said. International experts predict a five-degree
leap in such a worst-case scenario.
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- The NASA-led researchers were able to measure Earth's
energy imbalance because of more precise ocean readings collected by 1,800
technology-packed floats deployed in seas worldwide beginning in 2000,
in an international monitoring effort called Argo. The robots regularly
dive as much as a 1.5 kilometres under the sea to take temperature and
other readings.
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- Their measurements are supplemented by better satellite
gauging of ocean levels, which rise both from meltwater and as the sea
warms and expands.
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- With these data, the scientists calculated the oceans'
heat content and the global energy imbalance. They found that for every
square metre of surface area, the planet is absorbing almost one watt more
of the sun's energy than it is radiating back to space as heat ñ
a historically large imbalance. Such absorbed energy will steadily warm
the atmosphere.
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- The 0.85-watt figure corresponds well with the energy
imbalance predicted by the researchers' supercomputer simulations of climate
change, the report said.
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- Those computer models factor in greenhouse gases in the
atmosphere, including carbon dioxide, methane and other gases ñ
produced by everything from automobiles to pig farms. Those gases keep
heat from escaping into space. Significantly, greenhouse emissions have
increased at a rate consistent with the detected energy imbalance, the
researchers said.
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- "There can no longer be genuine doubt that human-made
gases are the dominant cause of observed warming," said Mr. Hansen,
director of NASA's Goddard Institute for Space Studies at Columbia University's
Earth Institute. "This energy imbalance is the 'smoking gun' that
we have been looking for."
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- Fourteen other specialists from NASA, Columbia and the
Department of Energy co-authored the study.
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- Scientists have found other possible "smoking guns"
on global warming in recent years, but Klaus Hasselmann, a leading German
climatologist, praised the Hansen report for its innovative work on energy
imbalance.
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- "This is valuable additional supporting evidence"
of manmade climate change, he told The Associated Press.
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- In February, scientists at San Diego's Scripps Institution
of Oceanography said their research ñ not yet published ñ
also showed a close correlation between climate models and the observed
temperatures of oceans, further defusing skeptics' past criticism of uncertainties
in modelling.
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- Average atmospheric temperatures rose about .6 degree
in the 20th century. The Intergovernmental Panel on Climate Change, a UN-organized
network of scientists, says computer modelling predicts temperatures rising
between 1.4 degrees and 5.7 degrees Celsius by 2100.
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- Besides raising ocean levels, global warming is expected
to intensify storms, spread disease to new areas, and shift climate zones,
possibly making farmlands drier and deserts wetter.
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