INQUIRY IN THE POLAR SCIENCE ELECTIVE

It’s Friday afternoon, and Christian Hagenlocher begins his Polar Science class with a classic gambit. “Imagine that aliens from outer space have demanded a drink of the coldest water on the planet,” Christian says. “Where do you think they should go?”

Students group together to discuss the question then bunch up at the front of the classroom to tally their results. Most students think the coldest water will be found in the South or North Poles, though there were also votes for Baffin Bay, the Mariana Trench, and a laboratory at Cornell.

Even after the votes are tallied, however, Christian doesn’t reveal the answer. Rather, in true inquirybased fashion, he has students conduct an experiment in water density that uses differing levels of salinity to create layers of colored water. The students team up, filling beakers with water, sharing the salt cannister, and trading bottles of food coloring. There’s a lot of laughter — and a lot of interest in the project.

You might wonder where all this is leading. It turns out that the coldest water on the planet is found in Antarctica, and that salinity plays a big role. “When sea water turns into sea ice, it releases the salt back into the water,” Christian explains. The result is that increasingly salty, dense, and very cold water — with temperatures lower than 32°F — accumulates below Antarctic glaciers.

“We’re going to take this exploration of temperature and salinity into a discussion about how melting freshwater glaciers impact ocean chemistry and, eventually, the food web,” says Christian. “Arctic and Antarctic ecosystems are both affected by these changes.”