As Congress continues debating climate change legislation, our leaders are faced with a choice: build on the progress we have made to curb emissions, grow clean energy companies and stop climate change, or stick our heads in the sand and delusionally hope the problem solves itself.

[IMGCAP(1)]New data from the Department of Energy should tip the scales dramatically in favor of strong, near-term action to contain emissions and expand clean energy. Put simply, U.S. carbon emissions have dropped by 9 percent since 2007. While the larger share of this drop is recession-driven, part of it is due to efficiency gains and an increasing movement to natural gas, wind, solar and geothermal energy.

This is a startling decline, considering that our national addiction to coal and oil had been growing steadily for over a century. Last year, oil use dropped 5 percent, coal 1 percent and overall carbon emissions 3 percent. Projections for this year, based on DOE data through September, show oil use down by an additional 5 percent and coal down by an impressive 10 percent, contributing to the 9 percent drop in overall emissions.

While the use of coal is falling, renewable energy deployment is rising. Last year, 102 wind farms came online, providing 8,400 megawatts of electricity-generating capacity — the equivalent of eight coal-fired power plants. U.S. solar cell installations are expanding at 40 percent per year and are poised to grow even faster. In the deserts of California, Arizona and Nevada, some 15 utility-scale solar thermal power plants that use mirrors to concentrate sunlight and generate electricity are under development. And 131 geothermal power plants are under development in the western states.

Utilities are facing falling demand for electricity not only because of the economic slump, but also because of advances in energy efficiency. The Rocky Mountain Institute calculates that if the 40 least efficient states were to achieve the electrical efficiency of the 10 most efficient ones, national electricity use would be reduced by one-third. This would allow the equivalent of 62 percent of the country’s 617 coal-fired power plants to be closed.

Oil use is declining and will drop further as the Obama administration’s new standards raise the fuel efficiency of new cars by 42 percent and light trucks by 25 percent by 2016. The really big gains in fuel efficiency will come with the shift to plug-in hybrids and all-electric cars. Electric motors are three times more efficient than gasoline engines and make it possible to run cars on domestic wind-generated electricity at a gasoline-equivalent cost of 75 cents per gallon.

Those Members of Congress who insist that America cannot make the transition from fossil fuels to renewable energy sources should realize that it is already happening, but that its pace right now is far too slow either to stave off the worst effects of climate change or to ensure that American companies and workers secure the economic benefits of the emerging global clean energy economy. China and the EU are creating incentives for clean energy companies to base operations within their borders, and huge solar and wind projects on a scale previously unimaginable are being announced on a regular basis in these regions.

Congress is considering legislation that would cut emissions from 2005 levels only 17 percent or 20 percent by 2020, but we have already cut them 9 percent in just two years. These Congressional targets are not nearly enough if the United States is to lead the world into the new energy era.

As we prepare for Copenhagen, we need a far more ambitious goal for cutting carbon emissions — the kind of emissions cuts the science tells us would be necessary to avoid “dangerous— climate change. More and more, that is looking like a cut of 80 percent from today’s levels by 2020, not 2050, a reduction that would halt the rise in the atmospheric carbon dioxide at 400 parts per million.

Momentum is building in the scientific community for much steeper cuts than Congress is considering. James Hansen, a leading U.S. government climate scientist, and Rajendra Pachauri, the head of the Nobel Prize-winning Intergovernmental Panel on Climate Change, are pushing for cuts that would lower atmospheric carbon dioxide concentrations, which are now 387 parts per million and climbing fast, to 350 parts per million as soon as possible.

We have both the technology and the wealth of wind, solar and geothermal resources needed to lead the world into the new energy era. We need to restore U.S. economic and political leadership to the level we showed when we restructured the U.S. industrial economy in a matter of months in 1942 as we mobilized for war and when we entered the race to put a man on the moon in 1961. This is a challenge we can meet, and the time to start is right now.

Lester R. Brown is president of the Earth Policy Institute and author of “Plan B 4.0: Mobilizing to Save Civilization.—