February 2nd, 2006
Hazel Barton’s teammate collects chunks of ice from the cave wall. The sample may contain an ice-dwelling oreanism — like the tardigrade shown above.
Hazel Barton awakens to the sound of a thundering crack. She realizes that the morning sun has warmed the ice near her tent, causing it to split. Barton unzips her tent and steps outside, shivering. She is in Greenland, a large island mostly north of the Arctic Circle where temperatures can plunge to a chilly -40°Celsius (-40°Fahrenheit) at night. For Barton — a scientist at Northern Kentucky University — it’s a far cry from home.
Why chill out in such a freezing scene? Barton has a cool reason. She’s here to explore one of Greenland’s many ice caves.
Deep Freeze
About 85 percent of Greenland is coated with moving sheets of ice called glaciers. In summertime, temperatures creep above freezing and melt the top layers of these glaciers. This melt-water flows along the glacier with the force of a raging river. Sometimes, the water flows into cracks in a glacier’s ice. As the forceful water pours into the cracks, it carves A out caves in the ice.
Barton and her team are about to explore one of these magnificent caves before it disappears. Unlike caves that are carved out of rock and last millions of years, ice caves last only one year. Why? There are two reasons. When air temperatures rise, the ice melts, turning the caves into liquid. Second, as the sun’s rays shine down on the glacier throughout the year, they heat the upper layer of ice, but the deeper layers remain unaffected. This difference in temperature within a glacier can cause the ice to split. And when this happens, an ice cave can collapse. Because of these factors, there are only two weeks a year for scientists to explore caves safely. “It has to be warm enough for you to comfortably be in the cave, but cold enough that the caves aren’t filled with water,” says Barton.
Understanding the risks, Barton and her teammates lower them selves more than 183 meters (600 feet) inside the cave. Once grounded, they notice bands of blue and white along the cave’s walls. The white bands are made of packed snow from Greenland’s winters. The blue bands are ice that has formed after snow melted in the summertime and refroze.
Hazel Barton (far right) and her teammates share a meal in a tent before exploring an ice cave. The group’s trip was filmed for an IMAX movie called Journey into Amazina Caves.
Cool Discovery
Barton runs her hand along one of these brightly colored walls. She wonders if they contain any organisms. To find out, she pulls an axe from her pack and chips away at a section of the wall. Before making her way out of the cave, she collects several chunks of ice to study.
Back in her tent, Barton melts the ice chunks and examines the water under a microscope. Peering closer, she spots a microscopic insect called a tardigrade. It looks like a six-legged gummy bear!
Tardigrades can survive freezing and thawing, and they can live up to 100 years! Barton and other scientists hope to learn how these animals thrive in such low temperatures.
Dripping Away
To learn more about such organisms, Barton believes that scientists must collect and study as many samples as possible from Greenland’s ice caves — before all these frosty structures are gone. What could possibly cause all the ice caves to disappear? According to many scientists, Greenland might not stay frozen forever. They believe that global warming may be increasing Earth’s temperatures.
Global warming occurs when gases such as carbon dioxide collect in a planet’s atmosphere. This buildup of gases traps the sun’s heat on Earth, and the world gets warmer as a result. Eventually, this heat could melt all the ice in Greenland, along with that at the North and South Poles. “There wouldn’t be any more ice caves,” says Barton.
Scientists are currently looking for ways to stop or slow global warming so that ice in Greenland and other places will stick around far into the future. According to Barton, “When more people start paying attention to global warming, they may find ways to prevent it.”
Words to Know
Glacier — a large sheet of ice flowing very slowly through a valley or spreading outward from a region
Meltwater — water that comes from melting snow or ice
Global warming — an increase in Earth’s average temperature overtime
Carbon dioxide — a colorless, odorless gas that is present in the layers of Earth’s atmosphere
Atmosphere — layers of gas that surround a planet
By: Brownlee, Christen, Scholastic SuperScience, Feb2006