Enlarge / Wolf Point Creek is likely the most-well-studied glacier-fed stream in the world. (credit: Elizabeth via Flickr (CC BY-NC 2.0) )

Pushing off from the dock on a boat called the Capelin , Sandy Milner’s small team of scientists heads north, navigating through patchy fog past a behemoth cruise ship. As the Capelin slows to motor through humpback whale feeding grounds, distant plumes of their exhalations rise from the surface on this calm July morning. Dozens of sea otters dot the water. Lolling on backs, some with babes in arms, they turn their heads curiously as the boat speeds by. Seabirds and seals speckle floating icebergs in this calm stretch of Alaska’s Glacier Bay.

Some two hours later, the craft reaches a rocky beach where Wolf Point Creek meets the sea. The creek is a relatively new feature on the landscape: Land at its mouth first became ice-free in the 1940s due to the melting and retreat of a glacier. It took shape through the 1970s, fed by a mountain lake that slowly formed as an isolated chunk of glacier ice slowly melted. Wolf Point Creek is special because almost its entire life span — from the first, sparse trickles melting out under the ice edge to a mature stream ecosystem teeming with aquatic life, from tiny midge larvae to small fish, and with willows and alder weaving along its edges — is known in intimate detail, its history painstakingly documented.

Milner, a stream ecologist at the University of Birmingham in the UK, has returned almost annually to this spot since the 1970s to catalog how life — particularly aquatic invertebrates — has arrived, thrived and changed over time. He was here to observe meager midges in 1977 and to spot a hundred prospecting pink salmon in 1989. A decade later, his team cataloged 10,000 of the fish spawning in Wolf Point Creek.

Enlarge / Past shorelines left deposits that are still visible on the hills near the Missoula Valley. (credit: Richard Forbes)

Had the city of Missoula, Montana, existed thousands of years ago, it would have been under water.

During the last Ice Age, a sheet of ice 20 miles wide got stuck in the Idaho panhandle and blocked the Clark Fork River, creating glacial Lake Missoula. At its highest, the water level reached 4,250 feet above sea level—over 1,000 feet above the present city’s altitude. The ice sheet ultimately gave way to the pressure of the water, and glacial Lake Missoula drained catastrophically.

It’s estimated that the biggest flood discharge reached 386 million cubic feet per second . At that rate, it took the lake only a few days to drain, with its waters eventually reaching the Pacific Ocean.

Enlarge (credit: De Agostini Picture Library | Getty Images)

Lake Whillans is a strange body of water, starting with the fact that there is liquid to fill it at all. Though buried under more than 2,000 feet of Antarctic ice, its temperatures climb to just shy of 0° Celsius, thanks to a combination of geothermal warmth, intense friction from ice scraping rock, and that thick glacial blanket protecting it from the polar air. Given the immense pressure down there, that’s just balmy enough to keep the lake’s water watery. Stranger still, Lake Whillans is also teeming with life. One survey a decade ago found thousands of varieties of microscopic critters, thought to be feeding on nutrients left by seawater that sloshed into the basin several millennia ago, when the glaciers last pulled back.

More recently, Chloe Gustafson, a geophysicist at Scripps Institution of Oceanography, arrived on the remote stretch of ice above Lake Whillans with a different mystery in mind: What’s happening underneath that lake? Antarctic researchers had long suspected the plumbing below the glacier went much deeper than they could see. Any groundwater beneath the lake would have implications for how the ice up above moves oceanward, and thus for how quickly it might contribute to rising seas . But they couldn’t definitively prove what groundwater was there. It was too deep, too ice-covered to map with the traditional tools of glaciology, like bouncing radar signals off the ice or setting off explosives and listening to the shockwaves .