The treeless ecosystem of mosses, lichens, and berry plants is giving way to shrub land and boreal forest. As scientists study the transformation, they are discovering that major warming-related events, including fires and the collapse of slopes due to melting permafrost, are leading to the loss of tundra in the Arctic.

In the past dozen years, three new diseases have decimated populations of amphibians, honeybees, and — most recently — bats. Increasingly, scientists suspect that low-level exposure to pesticides could be contributing to this rash of epidemics.

When the founder of the Whole Earth Catalog embraces nuclear power, genetically engineered crops, and geoengineering schemes to cool the planet, you know things have changed in the environmental movement. In an interview with Yale Environment 360, Stewart Brand explains how the passage of four decades — and the advent of global warming — have shifted his thinking about what it means to be green.

Much was left undone in Copenhagen, and the many loopholes in the climate accord could lead to rising emissions. But the conference averted disaster by keeping the UN climate negotiations alive, and some expressed hope that the growth of renewable energy technology may ultimately save the day.

The Copenhagen summit turned out to be little more than a charade, as the major nations refused to make firm commitments or even engage in an honest discussion of the consequences of failing to act.

As the world weighs how to deal with warming, the idea of human manipulation of climate systems is gaining attention. Yet beyond the environmental and technical questions looms a more practical issue: How could governments really commit to supervising geoengineering schemes for centuries?

Governments from the developed world will never come up with enough money to help poorer nations adapt to global warming and implement renewable energy technologies. The solution may lie in using a modest allocation of government funds to spur private sector investment in green energy projects in Africa, Asia, and Latin America.

As the UN conference enters its second and decisive week, the calls for strong global action to deal with climate change do not appear to be penetrating inside Copenhagen’s Bella Center.

The way that climate scientists have handled the fallout from the leaking of hacked e-mails is a case study in how not to respond to a crisis. But it also points to the need for climate researchers to operate with greater transparency and to provide more open access to data.

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.

The recent controversy over hacked e-mails in the climate science community has emboldened global warming skeptics who dismiss the notion that humanity is dangerously heating up the planet. But James Hoggan, founder of the Desmogblog, is taking on the deniers, accusing them of cynically obfuscating an issue long ago settled by mainstream science.

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.

Even as the climate science becomes more definitive, polls show that public concern in the United States about global warming has been declining. What will it take to rally Americans behind the need to take strong action on cutting carbon emissions?

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.

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.