For years we've heard environmental scientists and researchers tell us how climate change is having a profound effect on glaciers across the globe. In many parts of the planet, increased temperatures have caused the giant sheets of ice to dramatically recede or disappear altogether. That process has now begun to take place in one of America's most iconic landscapes - Yosemite National Park.

Last week, the National Park Service announced that Lyell Glacier, the largest inside the park, has stopped advancing and is losing substantial mass. The NPS, working in conjunction with the University of Colorado, conducted a four-year study of the glacier, measuring its movement by placing stakes along the ice and recording their positions. Over that four-year period, those stakes didn't move at all. The study also conducted research on the nearby Maclure Glacier, which runs adjacent to Lyell. The findings indicate that it is still advancing at a rate of about one inch per day, despite the fact that it has lost nearly 60% of its mass as well.

Glaciers build up over thousands of years due to the accumulation of ice and snow in mountainous areas. When they grow large enough their mass, combined with melt water, causes them to slide down hill at a generally very slow, but powerful, pace. When they stop moving altogether or start to retreat, it is because they no longer have the mass or moisture to push them downhill. This has increasingly been the case with some of the largest glaciers across the planet.

Research will continue over the next few years as scientists will record a host of climate data in and around both the Lyell and Maclure Glaciers. They'll monitor the thickness of the snowpack, range in temperatures and rate of ice melt in an effort to further understand the effects of climate change on the two bodies of ice. It seems clear, however, that warming temperatures have already begun to have an effect.

[Photo Credit: Greg Stock]

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