The major oil companies in the U.S. have not had to pay a price for the contribution their products make to climate change. But internal accounting by the companies, along with a host of other signs, suggest that may soon change — though the implications of a price on carbon are far from clear.

The prime cod fishing grounds of North America have been depleted or wiped out by overfishing and poor management. But in Arctic waters, Norway and Russia are working cooperatively to sustain a highly productive — and profitable — cod fishery.

The third-place winner of the Yale Environment 360 Video Contest focuses on a herd of bighorn sheep in Montana and features remarkable scenes of lambs as they gambol along the slopes of the northern Rockies. Produced by Jeremy Roberts, the video follows a field biologist as he monitors the sheep and talks about the possible impact of climate change on the animals’ future.

Chef  Dan Barber says the farm-to-table movement that he helped build has failed to support sustainable agriculture on a large scale. To do that, he says in a Yale Environment 360 interview, we need a new way of looking at diverse crops and the foods we eat.

The second-place winner of the Yale Environment 360 Video Contest examines the legacy of pollution in Anniston, Alabama, the former home of a Monsanto chemical factory. Produced by Spenser Gabin, the video tells the story of how PCBs from the Monsanto plant contaminated the town’s waterways and continue to taint the fish that are popular with local anglers.

"Badru’s Story," which documents the work of researchers in Uganda’s Bwindi Impenetrable National Park, is the first-place winner of the Yale Environment 360 Video Contest. Filmmakers Benjamin Drummond and Sara Joy Steele trek along with scientist Badru Mugerwa and his team as they monitor the impact of climate change on one of Africa’s most diverse forests and its extraordinary wildlife.

This September 1 marks the 100th anniversary of the death of Martha, the last known passenger pigeon on earth. The extinction of this once-abundant North American bird still stands as a cautionary tale.

Lian Pin Koh believes drones can be a key part of conservation efforts, particularly in remote regions. In a Yale Environment 360 interview, he talks about how his project, ConservationDrones, is promoting the use of drones for everything from counting orangutans to stopping poaching.

Hydraulic fracturing is about to move into the Canadian Arctic, with companies exploring the region's rich shale oil deposits. But many indigenous people and conservationists have serious concerns about the impact of fracking in more fragile northern environments.

Vultures are being killed on an unprecedented scale across Africa, with the latest slaughter perpetrated by elephant poachers who poison the scavenging birds so they won’t give away the location of their activities.

As president of the Humane Society of the United States, Wayne Pacelle has pushed the animal welfare group into areas that directly impact the environment. In an interview with Yale Environment 360, he talks about how what we eat, how we raise our food, and how we treat farm animals are basic conservation issues.

Along the Delaware River estuary, efforts are underway to restore wetlands lost due to centuries of human activity. With sea levels rising, coastal communities there and and elsewhere in the U.S. and Europe are realizing the value of wetlands as important buffers against flooding and tidal surges.

A Colombian conservationist has been locked in a contentious legal fight against a leading researcher who uses wild monkeys in his search for a malaria vaccine. A recent court decision that banned the practice is seen as a victory in efforts to restrict the use of monkeys in medical research.

Sea stars on both coasts of North America are dying en masse from a disease that kills them in a matter of days. Researchers are looking at various pathogens that may be behind what is known as sea star wasting syndrome, but they suspect that a key contributing factor is warming ocean waters.

From the Columbia River basin in the U.S. to the Prairie Provinces of Canada, scientists and policy makers are confronting a future in which the loss of snow and ice in the Rocky Mountains could imperil water supplies for agriculture, cities and towns, and hydropower production.

Long known as China’s granary, Hunan Province has been a major rice producer for the nation’s growing and increasingly urban population. But toxic pollution from Hunan’s mines and heavy metal plants has contaminated large tracts of its once-fertile farmland and put China's staple food supply at risk.

The 20th-century re-engineering of the Mississippi River wreaked havoc on natural systems and devastated once-abundant populations of native river shrimp. Biologist Paul Hartfield has focused his work on studying these creatures, which were known for making one of the world’s great migrations.

One of the world’s most polluting industries is the textile-dyeing sector, which in China and other Asian nations releases trillions of liters of chemically tainted wastewater. But new waterless dyeing technologies, if adopted on a large scale, could sharply cut pollution from the clothing industry.

Scientists in the U.S. and elsewhere are conducting intensive experiments to cross hardy weeds with food crops such as rice and wheat. Their goal is to make these staples more resilient as higher temperatures, drought, and elevated CO2 levels pose new threats to the world’s food supply.

Dairy operations in the U.S. are consolidating, with ever-larger numbers of cows concentrated on single farms. In states like Wisconsin, opposition to some large operations is growing after manure spills and improper handling of waste have contaminated waterways and aquifers.

For two decades, Jack Macy has spearheaded San Francisco’s efforts to become a global leader in recycling. In an interview with Yale Environment 360, he talks about how San Francisco has engaged the public in a recycling crusade that has resulted in the city reusing or composting 80 percent of its garbage.