Arctic Circle Ice
Photograph by Paul Nicklen
The Arctic Ocean's sea ice is in a "death spiral" due to rising temperatures, scientists said in 2008. Many marine species, such as these narwhals swimming through a bay in Nunavut, Canada, depend on the ice throughout their life cycles. Experts predict that summer Arctic ice may completely disappear within a few decades.
Polar Bear in Svalbard
Photograph by Ralph Lee Hopkins
Polar bears—like this one leaping between ice floes in Svalbard, Norway's Hinlopen Strait—live on the Arctic ice, hunting seals and other fatty marine mammals. But as the ice vanishes, some experts predict this predator will also disappear from the Arctic by 2050.
Alaska Permafrost Meltwater
Photograph courtesy Goddard Space Flight Center
Permafrost—the frozen soil that forms the backbone of the Arctic tundra—is melting due to climbing global temperatures. In Alaska, the mercury may rise by 1 to 5 degrees Celsius (1.8 to 9 degrees Fahrenheit) by 2100. In this false-color image of Alaska's North Slope, taken by NASA's Terra satellite, the blue-black color shows the many ponds of meltwater that collected on the coast in July 2007.
Alaska Permafrost Collapse
Photograph by Christine Dell'Amore
Thermokarst failures occur when permafrost—a layer of frozen soil in Earth's polar regions—thaws and becomes unstable, possibly releasing greenhouse gases into the atmosphere. Though the features occur naturally in some parts of the Arctic, many scientists suspect that rising temperatures are causing more to form. Until 2003, thermokarsts—such as this one, located about 155 miles (about 250 kilometers) north of the Arctic Circle—were unheard of in northern Alaska.
Photograph by Bernhard Edmaier
Freezing water from beneath Earth's surface forces the ground upward in Canada's Mackenzie River delta. Much of the basin is made up of permafrost, a layer of frozen soil in Earth's polar regions. Loss of permafrost due to climate change in Canada's Northern Territories may increase runoff and sediment flowing into rivers and make some slopes more unstable and vulnerable to landslides.
Caribou and Northern Lights
Photograph by Alaska Stock Images
Caribou—such as this large-antlered specimen silhouetted by Alaska's northern lights—are being affected as global warming accelerates in the Arctic. In Greenland, caribou time their births to coincide with the blooming of tundra vegetation. But as climate change causes plants to peak earlier, caribou newborns that eat the plants face tougher odds for survival.
Alaska Spruce Trees
Photograph courtesy Peter Essick/Getty Images
A forest of dead spruce trees near Homer, Alaska, is the victim of a tiny beetle that has boomed in the state's milder winters. Since the mid-1970s, about 50 percent, or 1 million acres (400,000 hectares), of the Kenai Peninsula's adult spruce trees have succumbed to the spruce bark beetle. The swaths of downed trees may actually turn forests from carbon sinks to sources, according to an April 2008 study. For instance, when dead trees decompose, they release the greenhouse gas carbon dioxide into the atmosphere.
Burned Alaskan Tundra
Photograph by Jason Stuckey
Fires are rare in the tundra, where "fuel"—in the form of tall plants or trees—is scarce. But as temperatures rise, thicker, taller shrubs are spreading throughout the region, raising the likelihood for more fires in coming years. Tundra burning may also release more organic carbon, a greenhouse gas currently stored in the soil, into the atmosphere.
Alaska Inuit Child
Photograph by Joel Sartore
The Inuit, a group of indigenous people living in the Arctic, are finding their land and cultures rapidly changing as climate change deepens its grip. As ice declines, so does the number of days available for Inuit to hunt for animals such as seals and walrus. Shifting winds are also reshaping ice formations used as landmarks for generations, making navigation more difficult. But, as Theo Ikummaq of Canada's Nunavut Province said, "We have lived in this region for centuries and we will continue to. As the climate changes, we will adapt."
@NatGeoGreen on TwitterTweets by @NatGeoGreen
NG's new Change the Course campaign launches. When individuals pledge to use less water in their own lives, our partners carry out restoration work in the Colorado River Basin.
The National Geographic Society aims to be an international leader for global conservation and environmental sustainability. Learn more about the Society's green philosophy and initiatives.