One of the current casualties of global warming is the size and scope of many of the world’s glaciers. From the Arctic to the Andes, many of these moving tongues of ice are melting faster than at any time in the past 10,000 years, when they were formed during the last Ice Age. While glaciers have been shrinking since the middle of the 19th century, the pace of their dissolution has accelerated dramatically in the last couple of decades. Glaciers in the Alps, in particular, are disappearing very rapidly, and some glaciologists predict that the Alps’ glaciers will be gone entirely by 2050. James Balog, a photographer for National Geographic, has been providing stark documentation of this trend through his Extreme Ice Survey (extremeicesurvey.org), a project that seeks to capture glacial retreat in a series of time-release photographs shot during every daylight hour from December 2006 through fall 2009 at locations around the world. Already the results are stunning. Glaciers are shrinking so quickly that one scientist I met at the National Center for Atmospheric Research in Boulder, Colo., was planning to take his kids to Alaska’s Glacier Bay now, since he wasn’t confident they could have the same experience once they are adults and could afford to go themselves. I’m feeling a similar compulsion to re-visit some of the spectacular glaciers I encountered while I was a tour director in Alaska during the 1980s and early ‘90s, while I still can. If you, too, would like to experience the cold majesty of these far-north frozen realms, consider a summer visit to this sampling in our 49th state: Columbia Glacier, Prince William Sound Among the world’s fastest-moving glaciers, Columbia has shrunk in length more than 9 miles since 1980. One of Alaska’s 51 tidewater glaciers, it winds down from the austere heights of the Chugach Range, discharging a mind-boggling amount of ice into the sea in a single day. Day boat cruises from Valdez or Whittier bring visitors to the terminal moraine. Harding Ice Field, Kenai Fjords National Park Covering 300 square miles, this massive ice cap spawns multiple tidewater glaciers that can be viewed on small boat cruises out of Seward. Exit Glacier, lying inland, is accessible from trails off Exit Glacier Road, which intersects the Seward Highway just north of Seward. (Note: Natural Habitat has a fabulous trip called Hidden Alaska that includes a small-boat cruise on the Fjords as part of a 13 day adventure). Portage Glacier, near Girdwood About an hour’s drive south of Anchorage, Portage Glacier pours into Portage Lake, filling it with bobbing icebergs. While the glacier was previously visible from the Begich, Boggs Visitor Center next to the lake, it is now best seen on a boat cruise across the lake on the mv Ptarmigan. The one-hour cruise takes visitors within 300 yards of the glacier’s face. Glacier Bay National Park and Preserve Glacier Bay lies about 50 air miles west of Juneau and encompasses 12 tidewater glaciers that disgorge giant bergs into the bay. It’s also home to a host of marine life, including whales, sea lions, seals and otters. While the bay is renowned for kayaking, the park service also offers a daily high-speed catamaran trip from Glacier Bay Lodge. At the head of the bay, you’ll experience life at its most primal, where barren bedrock has been newly uncovered by the receding ice and brand-new life is just beginning to take hold. Mendenhall Glacier, Juneau Just north of Alaska’s capital of Juneau, this 12-mile-long glacier is the most easily accessed portion of the 1,500-square-mile Juneau Icefield. Though often crowded with cruise ship day-trippers, it doesn’t take much to get close to the glacier in a more intimate way. Easy hikes to the face begin at the visitors center, or opt for an organized tour: options include a helicopter landing atop the ice, with a chance to walk on its surface wearing special foot gear, or a float trip on the placid Mendenhall River flowing from the edge of the glacier, punctuated with drifting chunks of ice.