• Ice in Motion

What’s the Question?

Science starts with a question. What is that? How does it work? Why does it do that? When does it change? These questions then drive a hypothesis, a guess at what the answer might be. There is then a long phase of mulling it over, looking at the problem from different angles, exploring previously collected data and contemplating how to find the answer. And then the work begins…

Many years ago, Dr. Jim Thomson and some of his collaborators started contemplating the role of waves in a changing arctic environment. It is well known that heat plays a big role in ice loss (warmer air and warmer water equals less ice), but waves have been more or less overlooked as a variable. But, as Jim knows well, they also play a crucial role in understanding this incredibly dynamic environment. And so, he set out to understand how waves act in the arctic and their impact on the ice and shore.

His question for this expedition is: what are the coastal effects of an increasing sea state in the western Arctic? In other words, what happens when bigger than normal waves hit the coastline? This question is not out of left field; Jim has been studying wave dynamics for twenty years, with much of his work focused in the polar regions. This expedition is building on his vast knowledge about wave mechanics and previous research trips into the arctic.

I’m going to boil down this background into a few bullet points to provide context for this voyage. Just please don’t tell Jim; he would probably shudder at my oversimplification of the last twenty years of his incredibly complicated work. Sorry, Jim.

· Surface waves require two primary variables. First, they need wind. Second, they need space to grow. This is called fetch, the distance of open water the waves have available to them.

· The ice in the arctic is disappearing rapidly due to a complicated web of interactions

· With less ice, there is more fetch and therefore bigger waves in the ocean (even at the same wind speeds).

· In the past, at this time of year, the Arctic coastline was locked in with ice that is grounded along the shore. This layer of shore-fast ice serves as a barrier, protecting the delicate tundra behind it from strong winds and big waves.

· There is less shore-fast ice than there used to be.

So, we know there is less ice and we know the waves are getting bigger in the arctic. But we don’t have a clear understanding of what happens when those big waves reach a shoreline no longer protected (or just barely protected) with its icy barrier. Jim’s hypothesis is that these bigger waves, caused by an increase in fetch, are breaking apart the shore-fast ice and therefore enhancing the melting already taking place. Smaller floating bits of ice melt faster than house-sized chunks anchored to the shore.

And that’s why we are currently motoring across the top of Alaska in the cold dark days of November; we are headed for an area that is developing shore-fast ice right now but is still open to a considerable amount of fetch. This is the sweet spot for collecting data and observations to work towards an answer to Jim’s question.

If it is true that waves are breaking up the shore-fast ice and contributing to a faster melt, these conditions may also generate a positive feedback loop: big waves break up ice; with less ice, there is more fetch and the waves can grow bigger. Bigger waves break up even more ice, which causes even more fetch and allows the waves to get even bigger. This is a positive feedback loop. It’s positive not because it’s a good thing (because it’s not) but because a small effect triggers changes that add to or exacerbate the original effect. (In a negative feedback loop, the reaction to an effect reduces or counteracts the original effect).

Some scientists have projected that within our lifetime we will see a runaway arctic melt, when the entire arctic becomes ice-free during the summer. A positive feedback loop, like the one Jim is studying now that links waves and ice, could contribute to a runaway event like that.

It’s intimidating. The terms scientists throw around casually these days, like “the new arctic” and “catastrophic melting,” are alarming. But knowledge is power. If we can understand the problem and its context, we can work towards a solution. We can figure out how to adapt and move forward confidently in this changing environment.

And that is why tomorrow we will once again suit up and scramble about on the icy back deck of the Sikuliaq, deploying data-collecting technology, taking water and sediment samples and recording observations in the twilight-daylight.

words by Becca Guillote

photos by John Guillote

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