How changing winter ice conditions around P.E.I. are letting the sea eat into its shores

The amount and duration of shore ice around Prince Edward Island has been changing in recent years, and researchers say shorter seasons are a concern because the ice provides a protective shield against winter storms and erosion.

The last two winters saw lighter ice conditions than historic normal levels. This winter, the ice was thicker, but it didn't form until February, almost six weeks later than it used to. 

"The past five years in particular have been very low on sea ice around Prince Edward Island... That's definitely unusual compared to our historical record," said Genevieve Keefe, a PhD candidate at UPEI's School for Climate Change and Adaptation.

Keefe studies coastal erosion and sea ice. She said P.E.I.'s ice season has decreased from between 10 and 15 weeks to an average of just nine weeks in recent years.

"One thing that we're concerned about is coastal erosion," Keefe said. "The sea ice provides kind of a barrier to the wind and the waves during the winter.

"Whenever we have winter storms that come in, that sea ice kind of can protect the shore from that wind and that waves if it's there during the winter. But if we don't have any sea ice during the winter, then our coast is essentially exposed for an additional three months during the year."

Parks Canada is also keeping a close eye on the changing ice conditions along P.E.I.'s North Shore, where the coastline has taken a hit from winter storms. 

"Over the last few winters, we have noticed a decreasing trend in the formation of near-shore ice within the park," said Lindsey Burke. "We are starting to notice that it's forming later in the season and not lasting as long throughout the winter season."

Burke said the ice plays an important role along the shoreline in a number of ways.

"It does form a protective barrier for the dune ecosystem, but it also acts as almost like a thermal blanket to the intertidal or the shoreline zone of our beaches," she said. "The sand underneath the ice foot is actually a little bit warmer than elsewhere.

Then there is the impact on living creatures. 

"We have invertebrate or insect communities that live in that intertidal zone that are an important food source, particularly for our shore birds that will be migrating back to the beaches to our area soon. And they need their energy... restored after such a long migration."

A sea ice specialist with Environment and Climate Change Canada says P.E.I.'s ice season is now on average six to eight weeks shorter than it used to be.

George Karaganis said warmer air temperatures and higher water temperatures have delayed the start of the ice season by about three weeks, meaning more risk to the shoreline.