How does a classic bar drink illustrate the effect of climate change on melting Arctic ice?
University of Alberta professor Bruce Sutherland can explain using an analogy—with a different refreshment.
“You’re walking along with your cup of coffee and the waves are sloshing until, finally, they spill on your pants,” Sutherland says.
The situation changes with a different drink order.
“A clever person gets themselves a latte, and you can walk around all you want and it doesn’t splash.”
The difference is in the foam.
Sutherland, a professor in physics and earth and atmospheric sciences, is one of two authors of a paper recently published in the Physical Review Fluids.
The pair tested a concern held by some oceanographers that waves in the Arctic are breaking up ice and accelerating the rate of melt.
Sutherland was discussing the theory with scientists at the Woods Hole Oceanographic Institution when he thought about every time he’s gone to a bar and a cap of foam has prevented his drink from spilling.
Every time, Sutherland has said he’s been amazed at the effect of the foam to damp—or reduce—the sloshing of his beer.
So, using a water tank and floating spheres that imitate ice chunks in the ocean, Sutherland and his co-author tested the damping effect of particles in a liquid.
The researchers found that, when sloshed, empty waves of water grow smaller over time. If the water contained particles, the waves would slow down and then stop. Effectively, the floating bits took energy from the moving waves.
Their experiment suggests waves in the Arctic are not causing ice to break and therefore melt at a faster speed. It’s good news.
But, there’s still work to be put into the experiment.
“It’s a big leap to go from my ideological experiment to the actual ocean. The biggest difference is—so that we could understand this problem theoretically—the floated spheres. But in reality, the ocean has blocks of ice you see bears walk over in nature programs,” Sutherland explained.
His test also didn’t replicate the ocean’s marginal ice zone, or a slushy area between open water and the blocks of ice.
However, the early results have left him optimistic.
In the last four decades, Arctic ice has grown about 40 per cent less in the summer, and about 10 per cent less in the winter.
The change has had huge impact on Arctic species, and others that live more south but which have migrated north in search for colder habitat—and in doing so, have created new competition.
A loss of Arctic ice also means more sunlight is absorbed by the ocean, rather than being reflected by the snow—causing an even faster warming of water and rate of melt.
Sutherland will continue his research in Edmonton and at Woods Hole Oceanographic Institution this summer, where he can better replicate the scale and conditions of the real ocean environment.
