Coastal erosion has doubled in some parts of the Western Arctic during the past 15 years, says a Dartmouth-based scientist who uses drones to survey the area.
Larger storms coupled with melting permafrost — both linked to global warming — are taking their toll on one of the world’s most rapidly changing coastlines, said Dustin Whalen, a scientist with the Geological Survey of Canada.
“Erosion is literally gobbling up land,” Whalen told Local Xpress.
In an effort to determine how much change is taking place along the Beaufort Sea, scientists would look at satellite and historical air photos of coastline, “but it really wasn’t giving us enough detail on what kind of volumes of change we’re seeing and how that change is actually taking place,” he said.
Using a couple of drones purchased off-the-shelf for about $1,500 each, scientists were able to shoot thousands of photos that enabled them to build 3D computer models of the coastline of the outer islands of the Mackenzie Delta and along the Tuktoyaktuk peninsula, including Cape Bathurst.
“Just by looking at the 3D image we are able to immediately decipher what kind of processes are happening in changing these cliffs so rapidly and how much volume of sediment is being lost on a yearly basis,” Whalen said.
“What we’re seeing is an actual acceleration in the change. So, since about the mid-1990s to 2000, coastal erosion has accelerated and, in fact, in some spots, it’s even doubled. Numbers are sort of varying throughout. You can go from one metre a year to two metres a year in the last 15 years. But in some cases … we’re at six to seven metres a year before the year 2000. But now we're looking at 16 metres a year. It’s spectacular to see these house-size blocks falling off the cliff year after year.”
In addition to figuring out the process driving the erosion, scientist with Natural Resources Canada want to know how much sediment is being deposited into the near shore, he said.
“That volume of sediment brings nutrients, brings carbon, and that has dramatic effect on near-shore ecosystems.”
More carbon can increase ocean acidification, which changes habitat for species living near the Arctic coastline, he said.
“That’s a speculation,” said Whalen, who normally works out of the Bedford Institute of Oceanography.
“But something we actually are seeing and measuring is this excess sediment in the last 15 years being deposited actually changes the bathymetry. So areas are getting shallower.”
Tuktoyaktuk harbour, for example, is getting shallower due to accelerating coastal erosion, said Whalen, who has been using the tiny northern hamlet as a base to survey about 1,000 kilometres of coastline for the past decade.
“We fly to a site and run two drones simultaneously, and they can stay in the air for about 20 minutes. Then they come back and we swap the batteries and send them back up.”
This past summer, over 54 missions, scientists collected more than 70,000 photos using the drones.
Whalen’s hoping to have a third drone in the air next summer.
“What makes the drone work amazing is the price,” he said.
A 2004 survey using a remote sensing method that used light in the form of a pulsed laser cost hundreds of thousands of dollars, he said. But the drone surveys cost a tenth of that, Whalen said.
About 85 per cent of the sites surveyed this summer were eroding, with the remainder seeing sediment growing along the coast.
“There is huge land loss and it’s being accelerated.”
Global warming is melting land laced with permafrost, he said. “It also decreases the sea ice. Decreased sea ice means more open water.”
That open water means there’s more room for storms to brew.
“We’re absolutely seeing more storms happening in the last two decades. So that’s higher water. That’s more frequent waves hitting the coast. So it’s kind of like a double-edged sword in the North. You’re seeing the normal coastal processes of erosion happening with the waves and the water hitting the coastline, which happens all over the world. But up there, you’re also seeing the melt.”
While there are communities around the world mitigating coastal erosion by building shore protection, scientists don’t know if that would work in the Arctic.
“The major unknown up north is how the shore protection reacts to not only the waves, but the melting as well,” Whalen said. “In one sense, we can protect against the waves because we know how to do that. It’s been done all over the world through coastal engineering. But no one really understands how much of the coast is actually eroding due to just straight melt. You can’t protect (against) that. You can maybe do crazy things like put a blanket over the coast or you can keep it frozen somehow, but, in my mind this is one of the huge challenges of coastal erosion up north.”
Next summer, Whalen hopes to use an undersea drone to get a look at what’s going on under the waves as well as above them.
“So when the drone is flying in the air, the (remotely operated underwater vehicle) is in the water doing the exact same thing,” he said.
“So then not only can we tell you how much sediment is being deposited, we’ll be able to tell you where it’s actually going.”