Over the last century, the intensive use of chemical fertilizers has saturated the Earth’s soils and waters with nitrogen. Now scientists are warning that we must move quickly to revolutionize agricultural systems and greatly reduce the amount of nitrogen we put into the planet's ecosystems.

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.

As the world warms, how different societies fare in dealing with rising seas and changing weather patterns will have as much to do with political, social, and economic factors as with a changing climate.

Although it is a heavily urbanized nation, fully two-thirds of Japan remains woodlands. Yet many of the forests are timber plantations inhospitable to wildlife, especially black bears, which are struggling to survive in one of the most densely populated countries on Earth.

Green rankings in the U.S. don’t tell the full story about the places where the human footprint is lightest. If you really want the best environmental model, you need to look at the nation’s biggest — and greenest — metropolis: New York City.

Interfering with the Earth’s climate system to counteract global warming is a controversial concept. But in an interview with Yale Environment 360, climate scientist Ken Caldeira talks about why he believes the world needs to better understand which geoengineering schemes might work and which are fantasy — or worse.

Of the various geoengineering schemes being proposed to cool an overheated planet, one approach — extracting carbon dioxide from the atmosphere using “artificial trees” — may have the most potential. But both questions and big hurdles remain before this emerging technology could be widely deployed.

The average American produces three times the amount of CO2 emissions as a person in France. A U.S. journalist now living in Europe explains how she learned to love her clothesline and sweating in summer.

By the end of the century, New York’s climate could resemble that of present-day Raleigh, North Carolina and its harbor could easily rise by two feet or more. Faced with this prospect, the city is among the first urban centers to begin changing the way it builds its infrastructure — and the way it thinks about its future.

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.

Stephen Kellert, a social ecologist, is a passionate advocate for the need to incorporate aspects of the natural world into our built environment. In an interview with Yale Environment 360, he explains what we can learn from cathedrals, why flowers in a hospital can heal, and how green design can boost a business’s bottom line.

For more than 40 years, scientists have dreamed of collecting the sun’s energy in space and beaming it back to Earth. Now, a host of technological advances, coupled with interest from the U.S. military, may be bringing that vision close to reality.

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.

China is on its way to becoming the world’s largest producer of renewable energy, yet it remains one of the most polluted countries on earth. A year after the Beijing Olympics, economic and political forces are combining to make China simultaneously a leader in alternative energy — and in dirty water and air.

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.

Setting unattainable emissions targets is not a policy — it’s an act of wishful thinking, argues one political scientist. Instead, governments and society should focus money and attention on workable solutions for improving energy efficiency and de-carbonizing our economies.

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.

As the International Whaling Commission debates whether to ban all whaling or to expand the limited hunts now underway, recent research has convinced some scientists that the world’s largest mammal should never be hunted again.

It took awhile, but the U.S. Midwest finally has recognized that the industries that once powered its economy will never return. Now leaders in the region are looking to renewable energy manufacturing and technologies as key to the heartland’s renaissance.

For years, the stumbling block for making renewable energy practical and dependable has been how to store electricity for days when the sun isn't shining and the wind isn't blowing. But new technologies suggest this goal may finally be within reach.

Researchers throughout the world are working to produce biofuel from algae. But a few are trying a decidedly novel approach: Using an abundant and freely available source — human waste — to make the fuel of the future while also treating sewage.