Why P.E.I.'s lack of sea ice this winter is a risk to shorelines
Clare MacKenzie | CBC News | Posted: February 3, 2023 9:07 PM | Last Updated: February 3, 2023
'Sea ice is very good at protecting against erosion'
Despite the extreme cold warning in effect for all of Prince Edward Island, it has been a relatively mild winter, and that's why Islanders may have noticed less sea ice along the province's shorelines.
P.E.I.'s ice season has decreased from 10-15 weeks to an average of nine weeks in recent years, according to Genevieve Keefe, a master's student at the UPEI School of Climate Change and Adaptation.
And since thick sea ice is effective at protecting against onshore waves and winds during storms, Keefe said the lack of ice makes the landscape particularly vulnerable to storm surge.
"Sea ice is very good at protecting against erosion, particularly landfast ice — so ice that is thicker and older and in contact with the land, so it's not moving as much," she said.
"That landfast ice can act as kind of a breakwater for incoming waves and do a really good job of protecting the shoreline against the power of the ocean."
Keefe said the more ice that builds up over the winter, the more protection it can offer the coastline.
"The seawater freezes at a temperature of about –2 C, and so we need temperatures below that and we need time," said Keefe.
"So we need kind of a prolonged period where the temperatures are below that level because water changes temperature at a slower rate than the air does."
Along with thick sea ice, dunes also offer natural protection against storm surge. But since post-tropical storm Fiona damaged many of the Island's dunes in September, they have not yet had time to properly regenerate.
"It's definitely an unfortunate situation. Not good luck by any means ... areas that were eroded by Fiona are more susceptible to further erosion in a lot of cases," said Keefe.
"The dunes which are normally dome-shaped, they look like they've been sliced off and that puts them at a greater risk because there's less vegetation ... also they've got a steeper front," she said.
"So now if the base gets washed away, the top can kind of fall down and we can have a more significant collapse."
Although Keefe can't say for certain whether or not P.E.I. will get any ice this winter, the extreme cold weather this weekend may have a silver lining.
"We are in the middle of a cold snap right now, so hopefully that'll kind of help build up a bit of an ice layer around the coast."