WASHINGTON (April 28, 2005) -- New research published today in the online version of the journal Science proves beyond a reasonable doubt that heat-trapping pollution is the primary cause of global warming, and warns that significant additional warming is "already in the pipeline" to occur.

In the article, "Earth's Energy Imbalance: Confirmation and Implications", scientists from NASA and the Department of Energy describe research on earth's "energy balance" -- the amount of heat absorbed by the sun versus heat emitted by the planet -- determined through precise measurements of increases in temperatures within the ocean. The researchers observed temperature increases that matched predictions of the effect of heat-trapping pollution that had been made with supercomputer-based climate models.

For the earth's climate to be stable, the amount of energy received from the sun must be balanced by the amount of energy radiated from the earth back to space. But the researchers found that the earth is now absorbing more energy than it is emitting, causing global warming.

Jim Hansen, director of the NASA Goddard Institute for Space Studies and the lead author of the study, said: "This energy imbalance is the 'smoking gun' that we have been looking for. The magnitude of the imbalance agrees with what we calculated using known climate forcing agents, which are dominated by increasing human-made greenhouse gases. There can no longer be substantial doubt that human-made gases are the cause of most observed warming."

An important implication of this finding is that there is already an additional 1 degree Fahrenheit of global warming in the pipeline, even if the amount of heat-trapping pollution in the atmosphere were stabilized at today's level.

The researchers found that the excess energy being received by the earth is 0.85 plus or minus 0.15 watts per square meter of the earth's surface. In aggregate, this is more than one-hundred times the output of all electric power plants in the world.

Daniel Lashof, science director, NRDC Climate Center, said: "While industry-funded deniers will probably continue their misinformation campaign, this study lays to rest any lingering doubts that heat-trapping pollution is responsible for global warming. There is no longer any excuse for delay in reducing global warming pollution."

The Natural Resources Defense Council is a national, nonprofit organization of scientists, lawyers and environmental specialists dedicated to protecting public health and the environment. Founded in 1970, NRDC has more than 1 million members and online activists nationwide, served from offices in New York, Washington, Los Angeles and San Francisco.