Hampered by a slow-moving Congress, the Obama administration is offering only modest greenhouse gas reduction targets at the Copenhagen conference. But limited federal action does not mean the U.S. is standing still: More than half of the 50 states are already taking steps to reduce emissions on their own.

Twelve years ago in Kyoto, the world was poised to act on a climate treaty but looked for a clear signal from the United States. Now, with the Copenhagen talks set to begin, the outcome once again hinges on what the U.S. is prepared to do.

On the eve of the Copenhagen conference, a group of scientists has issued an update on the 2007 report of the Intergovernmental Panel on Climate Change. Their conclusions? Ice at both poles is melting faster than predicted, the claims of recent global cooling are wrong, and world leaders must act fast if steep temperature rises are to be avoided.

For months, hopes that a climate treaty would be signed at the upcoming Copenhagen conference have been raised, then dashed, then raised again. Now, with prospects waning that a binding accord on reducing greenhouse gas emissions can be reached this year, ten environmental leaders and climate experts outline for Yale Environment 360 what they believe can still be accomplished at Copenhagen.

With skepticism growing about the chances of reaching a climate agreement next month in Copenhagen, Rajendra Pachauri, chairman of the Intergovernmental Panel on Climate Change, says he is “cautiously optimistic” that a treaty can still be signed. But in an interview with Yale Environment 360, Pachauri says the global community may have to move ahead without any commitment from the United States.

The U.S. can build all the wind turbines and solar arrays it wants, but until it does something about improving its outmoded electricity grid, renewable energy will never reach its potential. What we need is a new electricity transmission system, with the costs shared by all.

If a cap-and-trade bill passes Congress this year, it may include weak emissions targets and will likely need to be strengthened in the years to come. One way to guide future policy: create a Global Climate Change Index that could be used to track global warming’s impacts.

In the Yaak Valley of Montana, environmentalists have been talking to loggers, snowmobilers and other longtime opponents of wilderness protection about the future of public lands. Their accord is part of a cooperative effort that could lead to the first wilderness-area designation in the state in a quarter century.

John Holdren, the president’s top science adviser, is playing a key role in shaping the Obama administration’s strategy to combat global warming. In an interview with Yale Environment 360, Holdren discusses the prospects for achieving key breakthroughs on climate change, both in Congress and at upcoming talks in Copenhagen.

In an interview with Yale Environment 360, John Kerry praises the carbon cap-and-trade legislation now being debated in the U.S. Senate, describes its importance to upcoming climate talks in Copenhagen, and explains how he plans to help the landmark legislation clear the Senate and become law.

Wildlife biologists and climate scientists overwhelmingly agree that the disappearance of Arctic sea ice will lead to a sharp drop in polar bear populations. But some skeptics remain unconvinced, and they have managed to persuade the Canadian government not to take key steps to protect the animals.

Tighter restrictions on mountaintop removal mining are simply not enough. Instead, a leading climate scientist argues, the Obama administration must prohibit this destructive practice, which is devastating vast stretches of Appalachia.

As carbon cap-and-trade legislation works it way through Congress, the environmental community is intensely debating whether the Waxman-Markey bill is the best possible compromise or a fatally flawed initiative. Yale Environment 360 asked 11 prominent people in the environmental and energy fields for their views on this controversial legislation.

The United States powered its rise to affluence with fossil fuels, and China resents being told it should not be free to do the same. So as negotiators prepare for crucial climate talks this December, the prospects for reaching agreement remain far from certain.

As Congress struggles over a bill to limit carbon emissions, a cap-and-trade program is already operating in 10 Northeastern states. But the regional project's mixed success offers a cautionary warning to U.S. lawmakers on how to proceed.

Two prominent — and iconoclastic — environmentalists argue that current efforts to tax or cap carbon emissions are doomed to failure and that the answer lies not in making dirty energy expensive but in making clean energy cheap.

The days of freely dumping greenhouse gases into the atmosphere are coming to an end, but how best to price carbon emissions remains in dispute. As the U.S. Congress debates the issue, Yale Environment 360 asked eight experts to discuss the merits of a cap-and-trade system versus a carbon tax.

In an interview with Yale Environment 360, Bill McKibben explains why he’s now focused on organizing a citizens movement around climate change — and why he believes this effort is critical for spurring world leaders into action.

With carbon cap-and-trade legislation now on Washington’s agenda, companies and interest groups have been hiring lobbyists at a feverish pace. For every member of Congress, there are now four climate lobbyists, many of them hoping to derail or water down the effort to reduce greenhouse gas emissions.

Secretary of State Hillary Clinton’s trip to China could be the first step in forging a partnership between the world’s largest emitters of greenhouse gases. A leading China expert sets forth a blueprint for how the U.S. and China can slow global warming and strengthen their crucial relationship.