The inland Niger delta of Mali is a unique wetland ecosystem that supports a million farmers, fishermen, and herders and a rich diversity of wildlife. But now, the country’s president and Libyan leader Moammar Gaddafi have begun a major agricultural project that will divert much of the river’s water and put the delta’s future at risk.

The sludge spill in Hungary dominated world news for days, as horrific images of red-mud rivers appeared nonstop on the Internet, newspaper front pages, and TV screens. Yet other environmental threats — less visible, but potentially more devastating — often go largely unnoticed.

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.

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.

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.

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.

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.

In Africa and elsewhere, burgeoning population growth threatens to overwhelm already over-stretched food supply systems. But the next agricultural revolution needs to get local — and must start to see rising populations as potentially part of the solution.

Hydro fracturing is a profitable method of natural gas extraction that uses large quantities of water and chemicals to free gas from underground rock formations. But New York City’s concerns that the practice would threaten its water supply have slowed a juggernaut that has been sweeping across parts of the northeastern United States.

In recent months, protests over the severe illnesses caused by China's heavy industries have resulted in a crackdown on polluters. Leading the charge has been the state-run media, which the central government is now using to gain control over corrupt local authorities and powerful commercial enterprises.

Living on shifting land formed by river deltas, the people of Bangladesh have a tenuous hold on their environment, with cyclones buffeting coastal zones and rising seas posing a looming threat. But, as this Yale Environment 360 video report by Jonathan Bjerg Møller makes clear, many Bangladeshis already are suffering as a growing population occupies increasingly vulnerable lands.

In the last two decades, network theory has emerged as a way of making sense of everything from the World Wide Web to the human brain. Now, as ecologists have begun applying this theory to ecosystems, they are gaining insights into how species are interconnected and how to foster biodiversity.

The way that climate scientists have handled the fallout from the leaking of hacked e-mails is a case study in how not to respond to a crisis. But it also points to the need for climate researchers to operate with greater transparency and to provide more open access to data.