The Mekong has long flowed freely, supporting one of the world’s great inland fisheries. But China is now building a series of dams on the 2,800-mile river that will restrict its natural flow and threaten the sustenance of tens of millions of Southeast Asians.

By 2100, the world will probably be hotter than it’s been in 3 million years. In an interview with Yale Environment 360, paleoecologist Anthony D. Barnosky describes the unprecedented challenges that many species will face in this era of intensified warming.

The magnificent creature at the heart of the Greater Yellowstone Ecosystem now confronts two grave perils: the loss of its key food source because of rising temperatures, and increased killing by humans. A renowned grizzly expert argues that it’s time to once again protect Yellowstone’s grizzlies under the Endangered Species Act.

With global warming pushing some animals and plants to the brink of extinction, conservation biologists are now saying that the only way to save some species may be to move them.

With record-setting heat waves, bush fires and drought, Australians are increasingly convinced they are facing the early impacts of global warming. Their growing concern about climate change has led to a consensus that the nation must now act boldly to stave off the crisis.

Armed with vivid images from space and remote sensing data, scientists, environmentalists, and armchair conservationists are now tracking threats to the planet and making the information available to anyone with an Internet connection.

Two decades after the Exxon Valdez spilled 11 million gallons of crude oil into Alaska’s waters, the Prince William Sound, its fishermen, and its wildlife have still not fully recovered.

They’re calling it “global weirding” the way in which rising temperatures are causing species to change their ranges, the timing of their migrations, and the way they interact with other living things. And the implications of all this are only beginning to be understood.

Aided by new access to remote regions, researchers have been discovering new species at a record pace — 16,969 in 2006 alone. The challenge now is to preserve threatened ecosystems before these species, and others yet unknown, are lost.

Long an isolated land with abundant forests and biodiversity, Laos is rapidly developing as China and other Asian nations exploit its resources. One of the first casualties has been the wildlife, now being rapidly depleted by a thriving black-market trade.

Julienne Stroeve, a research scientist at the National Snow and Ice Data Center at the University of Colorado, has been closely monitoring the rapid loss of sea ice in the Arctic. In an interview with Yale Environment 360, she explains how the repercussions of that disappearance will be felt throughout the far north and, eventually, the entire hemisphere.

Led by China, the developing world is engaged in a flurry of dam construction, touting hydropower as renewable energy in an era of global warming. But critics point out that the human and environmental costs of dams remain high.

In response to industry pressure, the U.S. Food and Drug Administration has failed to set adequate restrictions on mercury levels in fish. Now the Obama administration must move forcefully to tighten those standards and warn the public which fish are less safe to eat.

The clearing of Indonesia’s rain forest for palm oil plantations is having profound effects threatening endangered species, upending the lives of indigenous people, and releasing massive amounts of carbon dioxide into the atmosphere.

Geologist Yong Yang has serious concerns about plans for a massive Yangtze River diversion project. When he went public with them, he found out how difficult it can be to challenge a government decision in China. The third in a series on Chinese environmentalists.

Despite the creation of protected areas in the Amazon and other tropical regions, rain forests worldwide are still being destroyed for a simple reason: They are worth more cut down than standing. But with deforestation now a leading driver of global warming, a movement is growing to pay nations and local people to keep their rain forests intact.

The international commission charged with protecting the giant bluefin tuna is once again failing to do its job. Its recent decision to ignore scientists’ recommendations for reducing catch limits may spell doom for this magnificent and endangered fish.

In the last eight years, vast areas of offshore Alaska have been opened to oil drilling. Now, a conservationist argues, the Obama administration must reverse the Bush-era policies if the state is to avoid irreparable harm to Arctic wildlife and to some of the most biologically productive waters on earth.

Scientists have been trying to identify the cause of a cancer epidemic that is wiping out Australia’s Tasmanian devils. Now new research points to an alarming conclusion: because of the species’ low genetic diversity, the cancer is contagious and is spreading from one devil to another.

The commitment by Wal-Mart, McDonald’s, and other major companies to buy only sustainably-caught seafood is an encouraging sign in an otherwise bleak global fisheries picture. After decades of government inaction and ineffective consumer campaigns, corporate pressure may finally be starting to turn the tide on reckless overfishing.

With food prices skyrocketing and climate change looming, the world needs a green revolution like the one a generation ago. But many valuable seed varieties have been lost ”“ and scientists now are scrambling to protect those that remain before they vanish down the genetic drain.