Washington: The sensitivity of earth`s
atmosphere is greater than previously thought and even slow
changes such as melting ice sheets amplify the initial warming
caused by greenhouse gases, a new study claimed.
A team of American scientists, studying a period of
high carbon dioxide levels and warm climate several million
years ago, have found that short-term changes like changes in
atmospheric water vapor, clouds, and sea ice amplify the
initial warming caused by greenhouse gases.
The study, published in the journal Nature Geoscience,
found that a relatively small rise in atmospheric carbon
dioxide levels was associated with substantial global warming
about 4.5 million years ago during the early Pliocene.
Coauthor Christina Ravelo at the University of
California said, "The study indicates that the sensitivity of
earth`s temperature to increases in carbon dioxide in the
atmosphere is greater than has been expected on the basis of
climate models that only include rapid responses".
"Carbon dioxide and other greenhouse gases trap heat in
the atmosphere, leading to increased atmospheric and
sea-surface temperatures," Ravelo said.
She added, "Relatively rapid feedbacks include changes
in atmospheric water vapor, clouds, and sea ice. These
short-term changes probably set in motion long-term changes in
other factors-- such as the extent of continental ice sheets,
vegetation cover on land, and deep ocean circulation--that
lead to additional global warming".
PTI
