Climate scientists and policy experts recognize the dire need to reduce the amount of greenhouse gases we dump into the atmosphere.

It's mission-critical: The threats posed by a warming planet — rising seas, melting polar ice caps, widespread destruction of coral reefs, to name a few — leave little room for equivocation.

And so far, efforts to reduce emissions from human activity, particularly carbon dioxide — the leading pollutant linked to global warming — have been alarmingly ineffective.

Emissions are actually increasing. An Energy Department report released last week showed that emissions rose in the U.S. by 1.4 percent in 2007. It reflects a longer-term trend: In 1990, about 6.2 million metric tons were released; in 2007, it was 7.2 million.

Worldwide, emissions are expected to increase by 86 percent from 2005 to 2030, the report concluded.

Clearly aggressive action is needed, both in the U.S. and globally. Stricter caps on carbon emissions are needed. And incentives for renewable energy must be a top priority.

The early signs are encouraging. President-elect Barack Obama has vowed to cut U.S. emissions to 1990 levels by 2020 and reduce them by 80 percent by 2050.

It's a good start. Not only will it reduce pollution, it will encourage the development of clean energy, providing an economic boost to the renewable-energy industry as well as the environment.

It's also a signal that the U.S. is willing to be a serious partner in global efforts to reduce greenhouse gas emissions.

Those efforts are continuing this week at an international climate change conference in Poland. Its purpose: to draft a new treaty to replace the U.N.'s much-maligned Kyoto Protocol, which expires in 2012 and which the Bush administration refused to sign.

As the world's biggest polluter, the U.S. has an obligation to play a leading role in the new treaty, to be completed in Copenhagen in 2009.

Because while the U.S. is cleaning house, it can use its growing expertise to spread the best green technology to the countries poised to replace it as the biggest greenhouse-gas polluters — poor developing nations, which still rely too heavily on cheap, dirty fuel.