April 6, 2010 – Original Source: Yahoo Green
Melting glaciers have become a well-known symbol of climate change.
Why? “It’s one of the simplest indicators of climate change,” says Eric Rignot, a senior research scientist at NASA’s Jet Propulsion Laboratory and a professor at the University of California, Irvine. “Glaciers melt when temperatures are increasing. It’s just basic physics.”
We also have access to numerous images of disappearing glaciers. Yet sometimes it’s hard to know exactly what the pictures are showing.
Below are some of the best photos that glaciologists say illustrate what they are seeing — a worldwide retreat in glaciers due to warming temperatures. The photos represent what is happening both in an individual glacier and in the various regions around the world.
“You don’t need to be a scientist to appreciate the magnitude of change of these glaciers,” says Rignot. “There shouldn’t be any doubt about these images.”
Left: Summer 1938. Right: Summer 2005. (Photo: U.S. Geological Survey)
Grinnell Glacier, Glacier National Park, Montana
These photos accurately reflect what is happening at Grinnell Glacier, which has been reduced by nearly 90 percent over the past century, and elsewhere in Glacier National Park, according to glaciologists. “When Glacier National Park was formed back in 1912 there were 100 glaciers in the park,” says Lonnie Thompson, a professor at the Ohio State University. “This year there are 26 glaciers, and those are expected to disappear within the next 30 years.”
August 1941. (Photo: U.S. Geological Survey)
August 2004. (Photo: US Geological Survey)
Muir Glacier, Glacier Bay National Park and Preserve, Alaska
Some of the largest glacial losses are happening in Alaska. Glaciologists say the above photos reflect real change that is taking place. “Alaskan glaciers are really shrinking a lot,” according to Marco Tedesco, an assistant professor at the City College of New York. “There is no debate about Muir Glacier. It’s a dramatic change to liquid water.”
Left: Summer 1917. Right: Summer 2005. (Photo: The Glacier Photograph Collection, National Snow and Ice Data Center/World Data Center for Glaciology.)
Pedersen Glacier, Kenai Fjords National Park, Alaska
Pedersen Glacier is another example of the massive glacial retreat taking place in Alaska. Glaciologists like the above photos because they are taken from the same spot and the perspective is the same.
Left: July 1978. Right: July 2004. (Photo: Glacier Photograph Collection of the National Snow and Ice Data Center/World Data Center for Glaciology.)
Qori Kalis Glacier, Peru
Professor Lonnie Thompson has been mapping the retreat of Qori Kalis Glacier up the valley since 1978. In fact, he took the photo on the right. “In our first 15 years of observation it was retreating at a rate of 6 meters per year and in the last 15 years it’s been averaging 60 meters per year,” says Thompson. “It is the world’s largest tropical ice cap and it has lost about 25 percent of its area since we started observing it.”
(Photo: NASA) Jakobshavn Isbrae, Greenland
Glaciologists agree that Jakobshavn is a good example of what’s happening with glaciers because it has a longer record than most glaciers. There is data going back as far as 1850. Jakobshavn was retreating slowly for a long time, but then in 2000 the glacier started retreating much more rapidly.
What’s more, three of the biggest glaciers in Greenland changed dramatically in the same time period, according to Leigh Stearns, an assistant professor at the University of Kansas. “These glaciers are really dynamic and they are changing much faster than we thought ice sheet glaciers could change,” she says.