Figure 1. Sea ice forming on the shores of Cambridge Bay, Nunavut
Ocean Networks Canada’s (ONC) cabled observatory in Cambridge Bay, Nunavut has been gathering real-time oceanographic data since 2012. This year, the data reveals that sea ice freeze-up occurred on 27 October, the latest date in eight years of monitoring the Arctic Ocean. By comparison, since 2012 the mean or average date of freeze-up is 5 October, a full three weeks earlier than 2020.
Figure 2: This climatology plot shows eight years of seasonal variations in key marine observations. The different plot lines show individual years (grey), mean date (black), plus one standard deviation (red), minus one standard deviation (blue), and present year 2020 (magenta).
“The Arctic is experiencing more rapid climate change than regions at lower latitudes,” says ONC’s associate science director Richard Dewey. “Among the changes are a shrinking ice pack and an extended summer season. A long-standing prediction is that, with warmer temperatures and longer summers, sea-ice melt and sea-ice freeze-up would occur earlier and later in the year, respectively. We now have some direct evidence of this.”
Figure 3. Cambridge Bay sea ice draft (blue) and air temperature (red) during late Oct 2020.
The instrument used to measure the sea ice draft—the ice thickness below the surface—is an ASL Environmental Services shallow water ice profiler, which uses sonar and works like an inverted echo sounder (Figure 4).