Photo Gallery: Earth Day in a Disappearing Wonderland

Great Barrier Reef

Photograph by Paul Sutherland

Brightly colored fish swim near sea fans and corals in the Great Barrier Reef. According to the environmental nonprofit WWF, 25 percent of marine life lives on coral reefs, and the Great Barrier Reef is home to thousands of species of coral, fish, mollusks, sea turtles, and mammals.

The United Nations Intergovernmental Panel on Climate Change has estimated that the Great Barrier Reef, and the nearly $5 billion tourist industry built around it, could be “extinct” by 2050.

Chihuahua Desert Landscape

Photograph by George Grall

Joshua trees and barrel cacti grow in the Chihuahuan desert, which straddles the border between the United States and Mexico. It is the largest desert in North America.

Despite its dry climate, the desert relies on the Rio Grande. But the river often runs dry before it hits the Gulf of Mexico due to irrigation withdrawals and recently erratic snowmelts at the river’s source in the Colorado mountains.

According to WWF, the construction of dams, groundwater extraction, deforestation, and agricultural pollution also threaten the Chihuahuan’s water sources.

Hawksbill Turtle

Photograph by George Grall

An endangered hawksbill sea turtle swims over a reef in the Caribbean Sea. Hawksbill turtles are threatened by destruction of their coral reef and shallow water feeding grounds due to ocean acidification and sea-level rise, which affect the habitats of the invertebrates they feed on. But the most immediate threats to hawksbills are illegal poaching for tortoiseshells—once openly traded in Japan and other countries—and coastal development that destroys habitat.

Rising sea levels and warming temperatures also have an effect on the turtles' breeding habits. More water means smaller beaches where female turtles lay their eggs. And the temperature of the eggs affects the sex of the hatchlings. The WWF estimates there are 8,000 nesting female hawksbill turtles left in the world.

Wild Salmon Run

Photograph by Michael S. Quinton

Alaskan salmon depend on clean, cold water, and face a slew of issues as global temperatures rise. Warmer water tends to fire up a fish’s metabolism so that it needs more food and takes longer to grow.

As less snow falls in the mountains, and melts earlier in the spring, there is less cool water along spawning runs.

By some estimates, nearly 40 percent of the Northwest salmon population could disappear by 2050.

Tibetan Glacier

Photograph by Xidong Luo, My Shot

Spring and summer runoff from glaciers in the Himalaya, like this one in Tibet, provide freshwater to hundreds of millions of people downstream through the Ganges, Yangtze, Mekong, and other major Asian rivers.

However, the glaciers are at risk of melting permanently as Earth warms and dramatic weather events become more frequent, potentially causing major spring flooding downriver and then summer droughts.  The WWF estimates that some glaciers in the Himalaya have been receding 33 to 49 feet (10 to 15 meters) a year, although some experts say glaciers there aren’t melting at such a fast clip.

Bengal Tigers

Photograph by Andrew Parkinson, Getty Images

A female tiger and her cubs rest in a national park in the Mahdya Pradesh province of India.

The coastal habitat of tigers (and people) in the Sundarbans—part of the largest remaining mangrove forest in the world near the Indian border with Bangladesh—are disappearing as sea levels rise. According to the WWF, there could be as few as 3,200 tigers left in the wild, and 15 percent of the islands that make up the Sundarbans could disappear by 2020.

Tour Boats on Yangtze River

Photograph by Justin Guariglia

Tourist boats wait for passengers in the Yangtze River, China. The Yangtze is longest river in Asia and the third-longest river in the world.

But the river is imperiled because shrinking Tibetan glaciers could cause massive flooding as they melt faster than normal.

The Three Gorges Dam, the world's largest, creates disruptions to wildlife habitat and human settlements.

Alerce Tree, Chile

Photograph by Fabian Gonzales, Getty Images

A hiker admires an alerce tree in the Valdivian rain forest, in southern Chile and Argentina.

Alerce can live to be 3,600 years old, and their rings show climate change over the course of their lives. Tree-ring studies show that rain has been less frequent and drought periods have been increasing, threatening the area with more frequent fires. Despite an international ban on trading its wood, the tree continues to be logged illegally, according to the WWF.