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.

For spurring the transformation to a low-carbon economy, the federal and state governments, universities, and the private sector must join together to create a network of energy research institutes that could speed development of everything from advanced batteries to biofuels.

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 global warming pushing some animals and plants to the brink of extinction, conservation biologists are now saying that the only way to save some species may be to move them.

Kelly Brownell has long studied the relationship between rising levels of obesity in the U.S. and the way our food is grown, processed, packaged, and sold. In an interview with Yale Environment 360, he discusses the common marketing and lobbying tactics employed by the food and tobacco industries.

Mostly conceived by international architects, China’s eco-cities were intended to be models of green urban design. But the planning was done with little awareness of how local people lived, and the much-touted projects have largely been scrapped.

Two decades after the Exxon Valdez spilled 11 million gallons of crude oil into Alaska’s waters, the Prince William Sound, its fishermen, and its wildlife have still not fully recovered.

They’re calling it “global weirding” the way in which rising temperatures are causing species to change their ranges, the timing of their migrations, and the way they interact with other living things. And the implications of all this are only beginning to be understood.

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.

For nearly a decade, The New Yorker’s Elizabeth Kolbert has been reporting on climate change. In an interview with Yale Environment 360, she talked about the responsibility of both the media and scientists to better inform the public about the realities of a warming world.

Aided by new access to remote regions, researchers have been discovering new species at a record pace — 16,969 in 2006 alone. The challenge now is to preserve threatened ecosystems before these species, and others yet unknown, are lost.

The number of vehicles worldwide is expected to reach two billion in the next two decades. Surprisingly, China where the demand for cars has been skyrocketing just may offer the best hope of creating a new, greener transportation model.

Long an isolated land with abundant forests and biodiversity, Laos is rapidly developing as China and other Asian nations exploit its resources. One of the first casualties has been the wildlife, now being rapidly depleted by a thriving black-market trade.

Julienne Stroeve, a research scientist at the National Snow and Ice Data Center at the University of Colorado, has been closely monitoring the rapid loss of sea ice in the Arctic. In an interview with Yale Environment 360, she explains how the repercussions of that disappearance will be felt throughout the far north and, eventually, the entire hemisphere.

On March 2, environmentalist Bill McKibben joined demonstrators who marched on a coal-fired power plant in Washington D.C. In this article for Yale Environment 360, he explains why he was ready to go to jail to protest the continued burning of coal.

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.

Issued less than two years ago, the report from the Intergovernmental Panel on Climate Change was a voluminous and impressive document. Yet key portions of the report are already out of date, as evidence shows the impacts of warming intensifying from the Arctic to Antarctica.

NASA’s Robert Bindschadler, a leading expert on glaciers and ice sheets, is part of an international team monitoring a large and fast-moving glacier in West Antarctica. In an interview with Yale Environment 360, he explains the dramatic impact this unstable mass of ice could have on global sea levels.

In the last few decades, urban sprawl, once regarded as largely a U.S. phenomenon, has spread across Europe. Now an emerging group of planners is promoting a new kind of development — mixed-use, low-carbon communities that are pedestrian-friendly and mass-transit-oriented.

If crucial climate negotiations later this year in Copenhagen are to have any chance of success, the U.S. must take the lead. To do that, President Obama needs to act boldly in the coming months.

Key developing countries have long been exempt from efforts to reduce greenhouse gas emissions. Now, as global climate talks move forward, that policy must change.