Global warming rate less than feared
High levels of carbon dioxide in the atmosphere may have less of an
impact on the rate of global warming than feared, a study revealed.
The authors of the study funded by the US National Science Foundation
stressed that global warming is real, and that increases in atmospheric
CO2, which has doubled from pre-industrial standards, will have multiple
serious impacts.
But the more severe estimates, such as those put forth by the United
Nations’ Intergovernmental Panel on Climate Change, are unlikely, the
researchers found in their study published in the journal Science.
Melting glaciers, a result of global warming.
Pic.courtesy: Google |
The 2007 IPCC report estimated that surface temperatures could rise
by as much as 2.4 to 6.4 degrees Celsius (4.3 to 11.5 Fahrenheit).
“When you reconstruct sea and land surface temperatures from the peak
of the last ice age 21,000 years ago -- which is referred to as the Last
Glacial Maximum - and compare it with climate model simulations of that
period, you get a much different picture,” said lead author Andreas
Schmittner, an Oregon State University researcher.
“If these paleoclimatic constraints apply to the future, as predicted
by our model, the results imply less probability of extreme climatic
change than previously thought.”
Scientists have long struggled to quantify ‘climate sensitivity,’ or
how the Earth will respond to projected increases in carbon dioxide, the
main greenhouse gas.
Schmittner noted that many previous studies only looked at periods
spanning from 1850 to today, thus not taking into account a fully
integrated paleoclimate date on a global scale.
The researchers based their study on ice age land and ocean surface
temperature obtained by examining ices cores, bore holes, seafloor
sediments and other factors.
When they first looked at the paleoclimatic data, the researchers
only found very small differences in ocean temperatures then compared to
now.
“Yet the planet was completely different - huge ice sheets over North
America and northern Europe, more sea ice and snow, different
vegetation, lower sea levels and more dust in the air,” said Schmittner.
“It shows that even very small changes in the ocean's surface
temperature can have an enormous impact elsewhere, particularly over
land areas at mid- to high-latitudes.”
He warned that continued, unabated use of fossil fuels could lead to
similar warming of sea surfaces today.
AFP |