What happens when the sea ice melts
In the Bear Glacier lagoon, at the moraine looking north. (Photo: Author)
This post continues the Glaciers of Kenai Fjords expedition, gathering photographic evidence of global warming in Alaska with researchers Bruce Molnia, Shawn Dilles, and Kim Angeli on board the Endeavour.
After lunch, we headed back up the river in the Scout. This time it was just me, Bruce, Kim, and Bella in the boat. The others stayed behind.
The tide had turned and the river was lower and much faster. There was a big, exposed rock in the mouth that we hadn’t seen before. But with the lighter load the little outboard got us up on a plane and we zoomed upriver, weaving between chunks of broken ice.
I made a tight turn around a large piece of ash-gray ice and ran the Scout up onto the gravel moraine. Bella was first out, as always. We three followed and I tied the painter to a rock while Bruce and Kim dropped their life jackets. Kim got out the white binder.
We walked down the gravel bar to find the exact spot where Grant and Higgins had taken a photo in 1909.
The gravel bar here is made up of small, rounded shingles of hard dark gray slate – professional-grade skipping stones. They crunched under our feet.
Across the river someone had tied strips of orange survey tape to two small trees a dozen yards apart, marking the approach for a bush plane landing spot on this side of the river. We could see the airplane tire tracks in the gravel right behind us, heading over the top of the moraine and toward the surf on the other side. It wasn’t much of a landing strip. I used to fly a bush plane in the southwest desert, a 1955 Cessna 180 taildragger. I would have had to give this one a lot of thought.
We found the 1909 spot. In the old photo, the glacier was in the foreground. Now it was far back and out of sight. The vegetation had changed, too. In the old photo, there was almost none. Now we were looking at a riparian forest. Bruce said that his work wasn’t just about the magnitude and speed of the glacial retreat. It also documents how quickly and in what order vegetation reclaims the land.
Back on the Endeavour, I winched the Scout onto the top deck, strapped it down, and got us underway. We headed due south, out the south end of Resurrection Bay. Bruce and Shawn were with me in the pilothouse.
“We’ve been looking at glaciers,” I said, “What about sea ice? Since it's already floating, when it melts it won’t flood the coasts, right?
“Sea ice is critical,” Bruce said. “In the last 40 years when we started satellite monitoring of sea ice, we’ve lost more than 80% of the ice that lasts through the year. All we get now in most places is ice that forms rapidly and melts just as rapidly. It used to be that 90 percent or more of the solar energy that hit sea ice was reflected into space. Now it warms melt ponds on the surface of the ice, accelerating its melting, and accelerating the warming of the ocean’s surface.
“The Arctic is warming so much more quickly than anywhere else,” he went on.“ Since 1949, the average temperature change for the entire state of Alaska is 4.3 degrees Fahrenheit. That’s in just 72 years. That’s twice the rate of the rest of the world. But the Arctic Ocean is warming even faster. Barrow and other stations on the shore have warmed 15 to 16 degrees Fahrenheit in winter, on average.”
Shawn asked, “How will that change ocean currents?”
“That’s an interesting question”, Bruce said. “What drives ocean circulation in the Atlantic? It’s sea ice in the Arctic. It’s fresh water concentrating brine below it, literally freezing the salt out of the seawater as it forms ice crystals. So, you get this dense brine forming below the sea ice. Over a short period of time, it sinks and it moves along the ocean bottom, and goes out Fram Strait, and drops over the lip of the shallow Arctic outlet into the North Atlantic, and that causes the North Atlantic circulation. That’s the engine.”
“So, if you no longer produce brine,” he added “you no longer produce cold bottom water. What’s going to drive the Gulf Stream?”
“And the Gulf Stream,” Shawn said, “determines the climate all the way up the Atlantic coast of the United States.
As we passed features formed by glaciers, Bruce pointed them out. There was an island with its top rounded off, with the gentler slope pointing back up the fjord, called a rouche moutonnée. It was once a headland, scalped from the back by a glacier long gone. The name is French, meaning “sheep-shaped rock.” The whole peninsula was a long, ragged chain of round anchorages with sharp steep walls, like volcanic craters, called cirques, Bruce said, French for circus rings. The thin jagged ridges separating them are called arêtes, ground like the blade of a serrated knife by the glaciers that cut the cirques. From above, on charts or satellite imagery, the peninsula looks like a long thin slice of pizza with bites taken out.
We passed through the Cheval Narrows and made a wide westerly turn around Aialik Cape into Aialik Bay and, just as the light was giving out, turned east into Paradise Cove, one of those steep and deep cirques. We anchored in 80 feet of water, not far from a saddle separating us from the next cirque, Cliff Bay. The dark green hemlocks grew down to the water, which was milky green from glaciers up the bay. The saddle was worn smooth by the bellies of otters taking the shortcut between this cirque and the next.
We were in for the night.
— William Urschel