Energy Imbalance Behind Global Warming
Climate change has been looked at from many angles. Here's another twist: Scientists have determined that more energy is being absorbed from the Sun than our planet reflects back to space.
This energy imbalance, the researchers said today, confirms other predictions that Earth's climate will warm by about 1 degree Fahrenheit (0.6 Celsius) by the end of this century.
The study is based on satellite data and computer models. It precisely measured ocean heat content over the past decade. The imbalance is due to increased air pollution, especially carbon dioxide and other greenhouse gases that act like a see-through blanket, letting sunlit in but trapping the heat it generates.
In scientific terms, the imbalance is 0.85 watts per square meter. It's equal to nature shining an extra 1-watt light bulb on every desk-sized patch of the planet.
It all adds up. If the imbalance were maintained for 10,000 years, it would melt enough ice to raise the oceans by six-tenths of a mile (1 kilometer), the scientists said.
The analysis lends support to the contentious idea that humans are contributing to the warming trend by burning gas, coal and other fossil fuels that generate greenhouse gases.
"This energy imbalance is the 'smoking gun' that we have been looking for," said lead researcher James Hansen, director of
NASA's Goddard Institute for Space Studies, part of the Earth Institute at Columbia University. "It shows that our estimates of the human-made and natural climate forcing agents are about right, and they are driving the Earth toward a warmer climate." The study is detailed in the online version of the journal Science.
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