Montana, Grinnell Glacier, Glacier National Park

The most-studied glacier in the park lets you see global warming in action.

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Glacier’s namesake ice masses are melting faster than soft-serve on Phoenix blacktop. Well, not really, but if temperatures increase as rapidly as most models predict, these colossal chunks of ice will disappear by 2030. Even if temperatures remain stable, they’ll melt by 2070. Worldwide glacial melt rates have doubled in the last 10 years, and America’s favorite wilderness park is a showcase for this disturbing phenomenon.

But there’s more to it than that. Receding glaciers lift the curtain on new, untouched land every year, opening acres of rugged terrain for off-trail hiking and scrambling. One of the best places to get close to the action is the extensively studied Grinnell Glacier, reached via its 5.5-mile namesake trail, beginning near the Many Glacier Lodge complex. In 1850, Grinnell Glacier covered approximately 576 acres. By 1993, the glacier had receded 62 percent to about 216 acres. Sperry Glacier is also on the retreat, and can be seen via the 10.4-mile trail starting at Sperry trailhead across from Lake McDonald.

Contact:Glacier National Park, (406) 888-7800;