Biodiversity is everywhere on Earth. It encompasses all living things as they interact with each other and their surroundings. The diversity of the environment creates unique communities of plants, animals and microorganisms, called ecosystems.

Biodiversity in extreme ecosystems has been first to feel the impact of global warming. Some species migrate to new, more comfortable terrain. Others, such as those specially adapted to live on ice floes, could become extinct if their environment changes too much, too fast.

Scientists reporting for the Intergovernmental Panel on Climate Change have found greenhouse gas emissions from human activities to be a significant factor in the rapid rise of global temperature. Immediate reduction in those emissions is essential to avoid extinctions, they say.

This wildlife corridor near Pound Ridge, New York, is a rich ecosystem with resources that support many levels of life and a wide variety of species. In contrast, deserts are inhabited only by species adapted to environments with little water. Life forms in such extreme ecosystems can be threatened by the smallest changes.

A newborn leatherback sea turtle crawls to the sea across a North Carolina beach. Its nest produced about 200 turtles, but only about 10 percent will survive. It can grow to 900 kilos and is the largest living turtle. Chief threats to this turtle, listed as endangered worldwide by the U.S. Fish and Wildlife Service (USFWS), are entanglement in fishing nets and ingestion of plastic bags.

A Mexican gray wolf roams the Sevilleta National Wildlife Refuge in New Mexico. A subspecies of the endangered gray wolf, it was nearly extinct in the 1970s but a successful USFWS reintroduction program, in cooperation with state, local and tribal agencies in the Southwest, has revived the population.

A female polar bear and her cubs rest on pack ice in northern Alaska’s Beaufort Sea. The bears evolved to live on ice, and do not thrive on land. With their habitat rapidly melting, they are seriously threatened. “As far as rescuing polar bears before their habitat disappears, there really is no rescue,” expert Steven Amstrup says. Scientists say reduction of greenhouse gas emissions is urgent to save their habitat.

Changing Arctic temperatures also affect the caribou, called reindeer in Europe. Warming causes more rain, which then freezes hard, preventing caribou from foraging for food. Other threats to caribou are snowmobiles, mining and oil-drilling operations.

Elephants have strong social bonds and look after each other in their herds. Besides habitat degradation and human encroachment, elephants in Asia and Africa are victims of poachers, who kill thousands of animals annually for their ivory tusks. The small South Asian herds, living in shrinking ranges, are especially vulnerable. The United States works with governments and international nongovernmental groups to stop the illegal ivory trade in Africa and Asia.

Tusks of Asian and African elephants fetch a high price in China, Japan and Thailand, where they are used for ornamental carvings. Poachers are depleting wildlife preserves that are home to elephants in India and Africa to feed the illegal trade. These tusks and ivory carvings were confiscated in Hong Kong.

A tiger hunts in the Siberian Tiger Park in Harbin, China. Once plentiful throughout Asia from the Caspian Sea to the islands of Indonesia, only a few thousand tigers remain in the wild, living in isolated swaths of habitat. The United States supports tiger conservation and opposes trade in tiger parts, which are used in traditional Oriental medicine. Tiger skins are status symbols in Tibet.

A mountain gorilla holds her infant son at the Kahuzi-Biega Nature Park near Bukavu, Democratic Republic of the Congo. All species of gorillas are endangered, the mountain gorillas critically so. They number in the hundreds. The United States is a member of the Congo Basin Forest Partnership, working to conserve gorillas, chimpanzees and their habitats. The populations have been decimated by hunting and disease — or simply eliminated by local militias to clear forests for mining or charcoal production.

A honeybee collects pollen from a daisy in Centralia, Washington. Bee populations, essential to American agriculture, are in crisis after mysterious and widespread die-offs over the past several years. The U.S. Department of Agriculture is taking a lead, working with other government agencies and universities to determine causes of colony collapse disorder. Without bees to pollinate them, certain fruits, nuts, vegetables and other crops are jeopardized.

A northern spotted owl roosts in the Tahoe National Forest in California. This owl has been the focus of controversy and lawsuits between environmental groups that wish to conserve old-growth forest habitat where the owls live and developers or loggers whose operations will disrupt it.

The monarch butterfly migrates between Canada and central Mexico. Disappearance of habitat on their migration routes has worried conservationists. The World Wildlife Fund (WWF) actively promotes restoring and preserving forest habitats where the butterfly hibernates.

Two giant pandas play in the forest at Wolong National Nature Reserve in Sichuan, China. Pandas have suffered from severe loss and fragmentation of habitat and poaching. WWF estimates there are only about 1,600 left in the wild. American scientists from the Smithsonian National Zoological Park and other U.S. institutions have ongoing programs with China to help conserve the pandas.

A bald eagle soars over the Lower Klamath National Wildlife Refuge in Oregon. The national bird of the United States, the eagle was critically endangered by hunting and pesticide poisoning. Its recovery from the 417 nesting pairs in 1963 to an estimate of more than 10,000 pairs is a conservation success. It was taken off the U.S. endangered species list in June 2007, but continues to be protected and monitored.

Biodiversity is at risk all over the world, but there’s a lot each of us can do to help protect the world’s ecosystems

All photos © AP Images