A “lake star” that formed on a Fairbanks lake.

Tohru Saito photo.

As Alaska’s billion lakes become colder and harder, some of them will sport mysterious, spidery cracks extending from small holes in the ice. This phenomenon inspired a geophysicist to figure out what he calls “lake stars.”

“I thought something so pretty and relatively commonly observed should be understandable, so I pursued it,” said Victor Tsai, who wrote perhaps the only paper in existence on lake stars.

An American dipper on the Sanctuary River in Denali National Park.

Photo by Ned Rozell.

On the upper Chena River in the heart of a cold winter, a songbird appeared on a gravel bar next to gurgling water that somehow remained unfrozen in 20-below zero air. Then the bird jumped in, disappeared underwater, and popped up a few feet upstream.

The bird continued snorkeling and diving against the current of the stream, which is so far north that in December direct sunlight never touches it, instead bathing only the tops of spruce trees with a ruby light.

Matt Druckenmiller tows a sled over sea ice in Barrow this spring. His sled contained instruments that measured the thickness of the ice.

Photo courtesy Hajo Eicken.

As the northern end of the globe nods away from the sun at fall equinox, the amount of sea ice floating on the northern oceans is now at the lowest amount ever detected by satellites, a period that goes back to 1979. This new sea-ice minimum follows an extremely cold Alaska winter that led to the formation of thick ice off the northern coast. In spring 2012, it looked like old times for ice floating off northern Alaska.

From left, Erin McQuin of Snohomish, Washington, instructor Marijke Habermann, a graduate student at the University of Alaska Fairbanks, and Heather Gregory of Anchorage. Habermann had just helped the girls cross a Gulkana Glacier stream on their way back down the glacier after being stuck at a higher camp for an extra night due to a storm. The streams and the glacier were slippery that day after more than 36 hours of continuous rainfall.

Photo by Joanna Young.

This summer, the Girls on Ice program visited an Alaska glacier for the first time. It probably won’t be the last, said organizer Joanna Young.

“We talked about how the girls would be inspired, but we didn’t count on how much we would be inspired,” said Young, a graduate student in the College of Natural Science and Mathematics at the University of Alaska Fairbanks. In July, she, two other grad students, and a mountaineer led nine teenage girls onto Gulkana Glacier for eight days of science and life on ice.