Will ice floating within the Arctic Ocean move faster or slower over the approaching a long time? The reply to this query will tell us whether marine transportation will be expected to get roughly hazardous. It may additionally have necessary implications for the speed of ice cover loss, which is hugely consequential for Northern Indigenous communities, ecosystems, and the worldwide climate system.
While observational data suggest the trend has been towards faster sea ice speeds, climate models project that those speeds will decelerate through the summer season. This contrast has led to some questions across the plausibility of the model projections.
In a brand new paper published today in The Cryosphere, Lassonde School of Engineering Associate Professor Neil Tandon and Postdoctoral Visitor Jamie Ward found that, while the mechanisms driving the ice slowdown remain plausible, questions remain regarding the timing of the slowdown.
“Understanding how sea ice motion goes to vary is clearly of interest, and yet we didn’t really know if what the models were projecting was reasonable,” says Tandon, who can also be with the Centre for Research in Earth and Space Science (CRESS) at York University. “Plainly we will expect sea ice to proceed to hurry up for a while, but there will likely be a degree in the approaching a long time when the dynamics will shift.”
Floating sea ice presents a selected hazard for marine transportation, says Tandon, pointing to a dramatic example from 2017 when sea ice trapped and sunk two fishing boats around Newfoundland. And the faster the ice, the more hazardous the conditions.
To know why sea ice has been speeding up, Tandon says a spring is usually a useful analogy. As temperatures warm and the ice thins, it might probably expand and contract more readily, just as a spring product of thinner metal can expand and contract more easily in comparison with a spring product of thicker metal.
“Because the thinner sea ice expands and contracts more, it generates more momentum for the ocean ice, similar to certainly one of those spring-loaded toy cars goes faster the farther back you pull it,” explains Tandon.
Nonetheless, this is just not the one force acting on the ice, and when the ice gets thin enough, the inner stresses that produced “springiness” begin to fade and other forces begin to dominate.
“As ice enters what they call a free drift state, the inner stress becomes negligible, and the external forces of wind and the ocean surface tilt begin to dominate. The models suggest that changes within the wind and ocean surface tilt will drive a slowdown of the ocean ice through the summer season.”
Tandon says that while the models generally agree that this summertime slowdown will occur, they don’t agree on when this slowdown will start. Some models suggest that the slowdown will start inside the following decade while others suggest it’ll start toward the tip of this century.
Faster ice drifts can create hazardous conditions for marine transport, so in that sense an ice slowdown might be seen as a positive, but Tandon says there are greater considerations.
“It doesn’t change the incontrovertible fact that sea ice cover is steadily declining, right? This can be a concern due to impact on ecosystems, the Indigenous populations that depend on with the ability to hunt certain animals, the animals’ ability to survive the changing habitat, and the general effect on the worldwide climate,” says Tandon. “But, I might say it’s marginally excellent news in that the models are suggesting that among the worst points we were expecting about ice cover decline will not be being projected.”
