The "monster" El Nino weather system expected to hit Canada's West Coast later this fall and winter could lead to higher tides, flooding and erosion in low-lying coastal areas, says a professor at the University of Victoria.
Ian Walker's warning comes out of part of a larger study by a group of researchers from five countries bordering the Pacific who looked into El Nino and La Nina weather systems. The study was published this week in the journal Nature Geoscience.
Thirteen researchers from universities and government agencies tried to determine if patterns in coastal change, such as erosion and flooding, could be connected to major climate cycles, like El Nino and La Nina, across the Pacific.
Walker, a geography professor whose specialties include beach and dune systems, coastal erosion and climate-change impacts, said he contributed data collected from the west coast of Vancouver Island, between Tofino and Ucluelet.
"What makes B.C. kind of distinct in the broader Pacific Basin is that we see coastal erosion and flooding responses for both El Nino and La Nina," said Walker.
"Now this year is a pretty monster El Nino, probably the largest ever witnessed. We know that in past El Ninos from here to California we've seen some of the highest historic rates of erosion. So we can prepare for that and we've seen that signal in our data."
El Nino is a natural, tropical, ocean temperature phenomenon, in which warm water near the equator in the Pacific moves towards South America's northern coast and then turns northward, as far as Haida Gwaii and Alaska, said Walker.
"As warm things expand, we see a higher water level, on the order of tens of centimetres, depending on where you are," said Walker. "So that's super imposed on the tides and storms are then superimposed on top of that."
The result can be higher ocean-water levels, he said.
Contrast that to a La Nina, which typically follows an El Nino and is a phenomenon where the upwelling of cold water off northwest South American results in cooler coastal ocean waters along B.C.'s coast, said Walker.
Less energy is available for storms and the ocean levels are lower, but what leads to erosion and flooding during a La Nina event is the track of the storms that plow directly into the central portion of Vancouver Island, said Walker.
"This is a big El Nino year, so we should be prepared but we should also be prepared as much for the La Nina which could follow in a couple years," said Walker.
The U.S. Geological Survey said in a news release that the research was important because the impact of El Nino and La Nina have not been included in studies about rising sea levels and coastal vulnerability.
Other universities that participated in the study included the University of Sydney and the University of New South Wales in Australia and New Zealand's University of Waikato.