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?

The chairman of the Intergovernmental Panel on Climate Change acknowledges it has been a rough few months for his organization. But, he argues, no amount of obfuscation and attacks by conspiracy theorists will alter the basic facts — global warming is real and intensifying.

With nearly $800 billion in drugs sold worldwide, pharmaceuticals are increasingly being released into the environment. The “green pharmacy” movement seeks to reduce the ecological impact of these drugs, which have caused mass bird die-offs and spawned antibiotic-resistant pathogens.

This April marks the 40th anniversary of Earth Day, an event that has attracted millions to environmental causes. But winning passage of meaningful legislation on climate change requires more than slogans and green talk — it demands intense, determined political action.

Once, on both sides of the Atlantic, fish such as salmon, eels, and, shad were abundant and played an important role in society, feeding millions and providing a livelihood for tens of thousands. But as these fish have steadily dwindled, humans have lost sight of their significance, with each generation accepting a diminished environment as the new norm.

The pronghorn, a close relative of the antelope, is the fastest mammal in North America and an iconic creature in the American West, where an estimated 700,000 roam the high desert and plains. In recent years, however, intensive development has begun to eat away at the pronghorn’s territory. In a video report for Yale Environment 360, journalists Daniel Glick and Ted Wood examine the fate of a herd of pronghorn that has migrated for more than 6,000 years from the Grand Teton Mountains to their wintering grounds.

During a half-century of studying Central American forests, Daniel Janzen has witnessed the steady destruction of tropical woodlands. In an interview with Yale Environment 360, the noted conservation biologist discusses his ambitious plans to use 21st-century technology to engage the public and halt forest loss.

Across western North America, huge tracts of forest are
dying off at an extraordinary rate, mostly because of outbreaks of insects.
Scientists are now seeing such forest die-offs around the world and are linking
them to changes in climate.

The obscenely profitable market for bluefin tuna in Japan has led to years of overfishing and left the world’s bluefin population badly depleted. A ban on the bluefin trade, if adopted at international talks this month, would go a long way toward giving this magnificent fish a chance to recover.