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.

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.

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.

With 20 percent of the world’s population but just 7 percent of its available freshwater, China faces serious water shortages as its economy booms and urbanization increases. The government is planning massive water diversion projects, but environmentalists say conservation — especially in the wasteful agricultural sector — is the key.

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.

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.

In the wake of the failed Copenhagen summit, prospects for cutting global CO2 emissions are worse than they’ve been in years. With talk of mandated cuts now fading and with countries exploiting loopholes, the world appears headed toward a flawed agreement based not on science but on politics.

Even after the failure to reach agreement on binding CO2 cuts in Copenhagen last December, the United Nations’ outgoing chief climate negotiator is confident that the world is making progress on global warming. The key, he says, is convincing all nations, particularly developing ones, that tackling climate change is in their long-term economic interest.

As utilities seek to build new nuclear power plants in the U.S. and around the world, the latest generation of reactors feature improvements over older technologies. But even as attention focuses on nuclear as an alternative to fossil fuels, questions remain about whether the newer reactors are sufficiently foolproof to be adopted on a large scale.

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.

For years, free-market fundamentalists opposed to government regulation have sought to create doubt in the public’s mind about the dangers of smoking, acid rain, and ozone depletion. Now they have turned those same tactics on the issue of global warming and on climate scientists, with significant success.

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.

As global warming intensifies, demands for human manipulation of the climate system are likely to grow. But carrying out geoengineering plans could prove daunting, as conflicts erupt over the unintended regional consequences of climate intervention and over who is entitled to deploy climate-altering technologies.

In response to the widening disaster in the Gulf of Mexico, government officials have approved a plan to intercept the oil by building a 45-mile sand berm. But scientists fear the project is a costly boondoggle that will inflict further environmental damage and do little to keep oil off the coast.

Environmentalist David Orr says the easy part of helping the United States live within its ecological limits may be passing laws, such as one that puts a price on carbon. The hard part, he maintains in an interview with Yale Environment 360, is changing a culture of consumption that causes extensive environmental damage — and unhappiness.