Using satellites, data from buoys and computer models to study the Earth's oceans, scientists from NASA, Columbia University in New York, and Lawrence Berkeley National Laboratory in Berkeley, California, took precise measurements of increasing ocean heat content over the past 10 years. Their results confirmed the suspected energy imbalance.

According to the study, Eart has an energy imbalance of 0.85 watts per meter squared -- large by standards of the planet's history. It will cause an additional warming of 0.6 degrees Celsius (1 degree Fahrenheit) by the end of this century, the researchers predict.

Consequence of Increasing Pollution

The research team offers this illustration as an aid to understanding the global warming trend: Think of a one-watt light bulb shining over an area of one square meter (10.76 square feet). Although that may not seem like much, adding up the number of feet around the world creates a big effect.

To put this number into perspective, an imbalance of one-watt per square meter, maintained for the past 10,000 years, is enough to melt ice equivalent to one kilometer (.6 mile) of sea level -- if there were that much ice.

"The energy imbalance is an expected consequence of increasing atmospheric pollution, especially carbon dioxide, methane, ozone and black carbon particles," said Jim Hansen of NASA's Goddard Institute for Space Studies, New York.

"These pollutants block the Earth's heat radiation from escaping to space, and they increase absorption of sunlight," he added. Hansen is the lead author of the new study, which appears in this week's Science Express.

Rate of Increase Doubled

As the Earth warms, it emits more heat. Eventually the Earth will be back in balance, if the greenhouse gas emissions are kept at the same level that exists today.

Scientists know it takes the ocean longer to warm than the land, and the lag in the ocean's response has practical consequences. It means there is an additional global warming of about one degree Fahrenheit that is already in the pipeline.

Even if there were no further increase of human-made gases in the air, climate would continue to warm by that amount over the next century.

Warmer worldwide water temperatures have many effects. "Warmer waters increase the likelihood of accelerated ice sheet disintegration and sea level rise during this century," Hansen said.

Since 1993, sea levels have been measured by satellite altimeters. Data has shown they have risen by approximately 3.1 centimeters or 1.26 inches per decade.

Although 3.1 centimeters is a small change, the rate of increase is twice as large as in the preceding century. Positive feedback comes into play, however, as the area of ice melt increases. The researchers agree that monitoring ice sheets and sea level is necessary to best ensure the global energy system is in balance.