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.

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.

Coffee production has long been vulnerable to drought or excess rains. But recently, a tiny insect that thrives in warmer temperatures — the coffee berry borer — has been spreading steadily, devastating coffee plants in Africa, Latin America, and around the world.

The Yangtze has been carved up by dams, used as an open sewer, and subjected to decades of overfishing. Now, Chinese scientists — alarmed by the disappearance of the Yangtze river dolphin and other creatures — are calling for a 10-year moratorium on fishing in the world’s third-longest river.

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.

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.

The polar bear has long been a symbol of the damage wrought by global warming, but now biologist Andrew Derocher and his colleagues have calculated how long one southerly population can hold out. Their answer? No more than a few decades, as the bears’ decline closely tracks that of the Arctic’s disappearing sea ice.

Primatologist Patricia Wright has spent the past 25 years studying — and protecting — Madagascar’s rich yet highly threatened biodiversity. Now, as many of the island’s remaining forests are being felled in the wake of a 2009 coup, Wright describes how she is helping organize the local residents and international conservation organizations to fight back.

Large corporations, not small-scale farmers, are now the major forces behind the destruction of the world’s tropical forests. From the Amazon to Madagascar, activists have been directing their actions at these companies — so far with limited success.

The images of pelicans and other Gulf of Mexico seabirds drenched in oil have stirred sadness and outrage around the world. But, says conservationist Melanie Driscoll, the unseen effects are probably far greater, with some birds perishing out of sight, far from shore, and others facing spill-related declines in the fish on which they depend.

The massive oil spill in the Gulf of Mexico is a warning, conservationists say, of what could happen in the Arctic as melting sea ice opens the Arctic Ocean to oil and gas drilling. Many experts argue that the time has come to adopt an Arctic Treaty similar to the one that has safeguarded Antarctica for half a century.

A prominent marine biologist says the impacts of the oil gushing into the Gulf of Mexico will persist for years, no matter when the flow finally stops. What’s more, scientist Thomas Shirley says that most of the damage remains out of sight below the surface, as creatures succumb to the toxic effects of the rapidly spreading tide of oil.

Within the planet’s oceans and soils are trillions of bacteria that store and release far more carbon dioxide than all of the Earth’s trees and plants. Now, scientists are attempting to understand how the world’s bacteria will influence — and be influenced by — a warming climate.

The tropical forest conservation plan, known as REDD, has the potential to significantly reduce deforestation and carbon dioxide emissions worldwide. But unless projects are carefully designed and monitored, the program could be undercut by shady dealings at all levels, from the forests to global carbon markets.

Is human activity altering the planet on a scale comparable to major geological events of the past? Scientists are now considering whether to officially designate a new geological epoch to reflect the changes that homo sapiens have wrought: the Anthropocene.

Among the natural treasures at risk from the oil spill in the Gulf of Mexico is the Breton National Wildlife Refuge, created by Theodore Roosevelt to halt a grave threat to birds in his era — the lucrative trade in plumage. Now, oil from the BP spill is starting to wash up on beaches where Roosevelt once walked.

Insecticides such as DDT have long been used to combat the scourge of malaria in the developing world. But with the disease parasite becoming increasingly adept at resisting the chemical onslaught, some countries are achieving striking success by eliminating the environmental conditions that give rise to malarial mosquitoes.

Our high-tech products increasingly make use of rare metals, and mining those resources can have devastating environmental consequences. But if we block projects like the proposed Pebble Mine in Alaska, are we simply forcing mining activity to other parts of the world where protections may be far weaker?