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GeoSigns @ National Geographic Magazine
   
 By Daniel GlickPhotographs by Peter Essick



Retreating glaciers, rising seas, and shrinking lakes are some of the global changes already under way.




Get a taste of what awaits you in print from this compelling excerpt.

"If we don't have it, we don't need it," pronounces Daniel Fagre as we throw on our backpacks. We're armed with crampons, ice axes, rope, GPS receivers, and bear spray to ward off grizzlies, and we're trudging toward Sperry Glacier in Glacier National Park, Montana. I fall in step with Fagre and two other research scientists from the U.S. Geological Survey Global Change Research Program. They're doing what they've been doing for more than a decade: measuring how the park's storied glaciers are melting.
 
So far, the results have been positively chilling. When President Taft created Glacier National Park in 1910, it was home to an estimated 150 glaciers. Since then the number has decreased to fewer than 30, and most of those remaining have shrunk in area by two-thirds. Fagre predicts that within 30 years most if not all of the park's namesake glaciers will disappear.
 
"Things that normally happen in geologic time are happening during the span of a human lifetime," says Fagre. "It's like watching the Statue of Liberty melt."
 
Scientists who assess the planet's health see indisputable evidence that Earth has been getting warmer, in some cases rapidly. Most believe that human activity, in particular the burning of fossil fuels and the resulting buildup of greenhouse gases in the atmosphere, have influenced this warming trend. In the past decade scientists have documented record-high average annual surface temperatures and have been observing other signs of change all over the planet: in the distribution of ice, and in the salinity, levels, and temperatures of the oceans.
 
"This glacier used to be closer," Fagre declares as we crest a steep section, his glasses fogged from exertion. He's only half joking. A trailside sign notes that since 1901, Sperry Glacier has shrunk from more than 800 acres to 300 acres (330 hectares to 120 hectares). "That's out of date," Fagre says, stopping to catch his breath. "It's now less than 250 acres (100 hectares)."
 
Everywhere on Earth ice is changing. The famed snows of Kilimanjaro have melted more than 80 percent since 1912. Glaciers in the Garhwal Himalaya in India are retreating so fast that researchers believe that most central and eastern Himalayan glaciers could virtually disappear by 2035. Arctic sea ice has thinned significantly over the past half century, and its extent has declined by about 10 percent in the past 30 years. NASA's repeated laser altimeter readings show the edges of Greenland's ice sheet shrinking. Spring freshwater ice breakup in the Northern Hemisphere now occurs nine days earlier than it did 150 years ago, and autumn freeze-up ten days later. Thawing permafrost has caused the ground to subside more than 15 feet (4.5 meters) in parts of Alaska. From the Arctic to Peru, from Switzerland to the equatorial glaciers of Irian Jaya in Indonesia, massive ice fields, monstrous glaciers, and sea ice are disappearing, fast.

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Interactive Image
Journey to Antarctica and enjoy the sights and sounds of penguins, seals, and other wildlife. Then download wallpaper and meet the fearless explorers of this frozen frontier.

Multimedia
VIDEO Learn about the rapid retreat of north polar ice and its repercussions for the planet.
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Courtesy of NASA
Forum
Climate change has shifted the natural rhythms and processes of our planet. What's happening to Earth's climate, and what are the implications for our future? What signs of climate change have you noticed in the flora and fauna around you?
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Drape your desktop with an ominous curtain of roiling smoke from a Fairbanks, Alaska, forest fire.

Postcards
E-greet a friend with the ice cover on Wisconsin's Lake Mendota.
Final Edit
Rescued from the cutting-room floor is this month's Final Edit, an image of Male, the island capital of the Maldives, at risk from the effects of rising sea level.


More to Explore

In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

Did You Know?
Greenhouse gases—carbon dioxide, water vapor, methane, and others—warm the Earth's surface and lower atmosphere by trapping heat radiated from Earth back to space. For thousands of years before the industrial revolution the levels of greenhouse gases in the atmosphere remained relatively stable, but since then human activity such as the burning of fossil fuels has caused those levels to rise. As the concentrations of greenhouse gases increase, they tend to intensify warming. The Intergovernmental Panel on Climate Change, a group created by the United Nations and the World Meteorological Association, concluded in its 2001 report that "most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."

The United States emits more carbon dioxide—one of those key greenhouse gases—than any other country in the world. In 2000 Oak Ridge National Laboratory ranked the world's nations by total carbon dioxide emissions from fossil fuel burning, cement production, and gas flaring as well as by per capita emissions. Their top five in total emissions  are the United States, China, Russia, Japan, and India. If you would like to see the entire list you can visit the
Oak Ridge website
 
—Abigail Tipton
Did You Know?


Find a listing of related websites and resources at Signs From Earth.

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