Researchers at the Max Planck Institute for Meteorology in Hamburg, Germany, along with the National Snow and Ice Data Center in Boulder, Colorado and University College in London, have worked how much we’re each shaving off the Arctic Ocean’s permanent ice pack—that dwindling and thinning cap of ice that remains in place at the end of summer.

Researchers used decades of data to calculate that on average, and not counting thinning of Arctic sea ice (a critical component of the total loss of ice mass) three square meters of sea ice—about the area of a full sheet of construction plywood—melt for every tonne of carbon dioxide released. They compared that to the CO2 released by various activities, on a per-capita basis, by various nationalities.

Based on the 20.6 tonnes of CO2 that Environment and Climate Change Canada says the average Canadian emitted in 2014, CBC News calculates that the average three-person household in the country is burning a hole the size of an NHL hockey rink through the Arctic’s permanent ice every 8.5 years.

The study also concluded that if humanity’s cumulative additional greenhouse gas emissions remain under 1,000 gigatonnes, Earth could retain “some Arctic summer sea ice cover.” But at present rates of emission, that budget could be used up, making summer sea ice a vanished memory by 2045.

But “this sounds like a rather crude equation,” said Cambridge University ocean physics professor Peter Wadhams, adding that the past linear progress of incremental melting on which the German-American team based its calculations may be a poor guide to the future. Citing Wadhams, CBC warned that “ice could disappear from the Arctic Ocean as early as 2017 or 2018 because of other factors triggered by human-made climate change, such as shifts in winds and rising sea temperatures.”