Sea ice, to a great extent, defines the Arctic. My first recollection of thinking about the Arctic was in elementary school when I looked at the white expanse at the top of a globe that depicted the extent of perennial sea ice. It was hard to conceive there was a place so cold it had an ice-covered ocean year-round.
Years later, in September of 1970, my personal relationship with Arctic sea ice began. The Coast Guard icebreaker I had boarded at Point Barrow to conduct seabird observations off Prudhoe Bay was prevented from traveling east to Prudhoe Bay due to heavy ice sea ice. The advancing ice then pushed us south and out of the Chukchi Sea in mid-October.
My connection with sea ice became more direct and intimate beginning in 1975, when I began my study of the Black Guillemot colony on Cooper Island. The island has always been surrounded by sea ice at the start of my field season in early June. In the past, thick and stable shorefast ice provided a way to transport gear and personnel to the island by snow machines pulling sleds, allowing us to avoid chartering an aircraft. My fresh water was supplied by snowdrifts on the sea ice, which persisted longer than those on land, and then later in season I would melt multi-year sea ice that used to wash up on shore throughout the summer. The pack ice was present right next to the island or a short distance offshore all summer. I realized that the proximity of the sea ice also meant that polar bears might be close to the Island, but the numerous seals seen resting on the ice meant the bears were likely well fed.
As my reliance on, and relationship with, Arctic sea ice was developing in the late 20th Century, I had no idea that its rapid decline in the 21st Century would become one of the most visible impacts of global warming. I followed the monitoring of the sea ice decline when I was not in the field, but during summer, I experienced the direct impacts of that decline. I can no longer travel to Cooper Island on shorefast ice, I need to gather rain for fresh water since multi-year ice has become a rarity, and I now regularly share the Island with polar bears stranded on land due to the loss of their sea ice habitat. The latter impact now has me carrying a shotgun wherever I go on the island and living in a cabin I acquired in 2003 after polar bears had trashed my tents.
Of course, it is the effect of sea ice loss on Mandt’s Black Guillemot, an ice-obligate seabird, that is the prominent ecological change that has been documented by this study. The subspecies is adapted to feeding on Arctic Cod and other prey found in the cold waters under and next to sea ice. For years, Cooper Island was a nesting location adjacent to ice-covered waters that, based on the colony’s breeding success, provided an abundance of food. However, since the turn of the century, increasing summer sea ice melt has meant parents often have to forage in relatively warm ice-free waters. In the absence of Arctic cod, the necessary switch to lower-quality and less-abundant prey has had a major negative impact on nestling growth and survival.
This June and through early July, sea ice cover in the immediate area of Cooper Island was high, which likely played a part in the good start to the guillemot’s breeding season. However, now the distance from Cooper Island to sea ice is greater than it has ever been at the start of the nestling growth period, with ice extent throughout the Arctic being at record low levels. Findings from earlier years with greatly decreased ice and warm ocean temperatures, such as 2017, are cause for concern about what the upcoming weeks of 2019 may hold for the birds currently breeding on the Island and their young who need regular deliveries of high-quality prey. This region has never been more ice-free and the immediate challenges faced by the guillemots have never been greater.
This field report is part of an ongoing series titled Arctic Change centered around George Divoky’s 45th field season studying Black Guillemots, sea ice, and climate change on a remote Arctic island off the coast of Alaska. To donate and support Divoky’s work on Cooper Island, visit the Friends of Cooper Island website.
Arctic Report Card: Update for 2018 by NOAA’s Arctic Program
Can These Seabirds Adapt Fast Enough to Survive a Melting Arctic by Hannah Waters
Europe’s Heatwave is About to Bake the Arctic by Andrew Freedman