The U.S. has invested billions of dollars trying to create a controlled form of nuclear fusion that could be the energy source for an endless supply of electricity. But as a federal laboratory prepares for a key test, major questions remain about pulling off this long-dreamed-of technological feat.

How significant would it be if America’s 29 million small businesses increased their energy efficiency and reduced their emissions? Judging from the example of one California entrepreneur, the impact could be far greater than you might expect.

Energy companies are rushing to develop unconventional sources of oil and gas trapped in carbon-rich shales and sands throughout the western United States and Canada. So far, government officials have shown little concern for the environmental consequences of this new fossil-fuel development boom.

Last spring, conservation groups and timber companies signed an historic agreement to protect a large swath of Canada’s boreal forest. In an interview with Yale Environment 360, the Pew Environment Group's Steven E. Kallick, a key player in the agreement, explains why the accord is integral to a larger plan to eventually preserve half of Canada’s extensive boreal forests.

When officials gather for an international summit on biodiversity next month, they might look to remind the world why species matter to humans: for producing oxygen, finding new drugs, making agricultural crops more productive, and something far less tangible — a sense of wonder.

Across the Far North, populations of caribou — an indispensable source of food and clothing for indigenous people — are in steep decline. Scientists point to rising temperatures and a resource-development boom as the prime culprits.

One of the more contentious issues facing climate scientists is whether rising ocean temperatures will cause more frequent and powerful hurricanes. In an interview with Yale Environment 360, Kerry Emanuel, of the Massachusetts Institute of Technology, says that amid the uncertainty, one thing seems likely: an increase in the most potent — and destructive — storms.

Ecuador's Yasuni National Park is one of the most biodiverse places on Earth and is home to remote Indian tribes. It also sits atop a billion barrels of oil. Now, Ecuador and the United Nations are forging an ambitious plan to walk away from drilling in the park in exchange for payments from the international community.

An activist caravan to bring one of Jimmy Carter’s solar panels back to the White House symbolizes the time that the U.S. has lost in developing new energy technologies ”“ and the urgent need for taking action on climate.

The freshwater eel, which spawns in the middle of the ocean, was once abundant in much of the world. But the proliferation of dams, coastal development, and overfishing have drastically reduced eel populations, with few defenders coming to the aid of these fascinating — though still not fully understood — creatures.

As climate scientists wrestle with the complexities of how the planet will react to rising greenhouse-gas levels, no variable is more difficult to decipher than the impact of clouds. But thanks to new satellite data and other technologies, clues are emerging that may help solve the puzzle.

Consumers now have little information about the true ecological impacts of what they buy. But that may be about to change, as new technologies that track supply chains are emerging and companies as diverse as Unilever and Google look to make their products more sustainable.

LEED certification has emerged as the green standard of approval for new buildings in the United States. But the criteria used for determining the ratings largely ignore factors relating to human health, particularly the use of potentially toxic building materials.

Earlier this year, 38-year-old environmental activist Michael Brune was named the unlikely choice to take over as head of the Sierra Club, the largest U.S. conservation organization. In an interview with Yale Environment 360, Brune says it’s time to move beyond overly accommodating strategies like those that failed to win passage of U.S. climate legislation.

The Gulf of Mexico’s capacity to recover from previous environmental assaults — especially the 1979 Ixtoc explosion — provides encouragement about the prospects for its post-Deepwater future. But scientists remain worried about the BP spill's long-term effects on the health of the Gulf and its sea life.

As warming intensifies, scientists warn, the oxygen content of oceans across the planet could be more and more diminished, with serious consequences for the future of fish and other sea life.

While some studies have suggested that frequent use of cell phones causes increased risk of brain and mouth cancers, others have found no such links. But since cell phones are relatively new and brain cancers grow slowly, many experts are now recommending taking steps to reduce exposure.

Ample blame exists for the demise of climate legislation in the U.S. Senate, from President Obama’s lack of political courage, to the environmental community’s overly ambitious strategy, to Republican intransigence. A way forward exists, however, to build on the rubble of the Senate’s failure to cap carbon emissions.

Environmentalists in the U.S. are increasingly trying to use the Endangered Species Act to ease the impact of global warming on numerous animals and plants, including the American pika. The goal is not only to protect the habitat of at-risk species but also to force reductions in greenhouse gas emissions.

A dispute between Egypt and upstream African nations has brought to the fore a long-standing controversy over who has rights to the waters of the Nile. The outcome could have profound consequences for the ecological health of the river and for one of the world’s largest tropical wetlands.

New technologies, feed-in tariffs, and tax credits are helping propel the small wind industry, especially in the United States. Once found mostly in rural areas, small wind installations are now starting to pop up on urban rooftops.