Now think of the secondary statistic. Every additional ton is an additional 32 square feet of lost Arctic ice. In other words, every American household melts 200 square feet of the ice cap every year just to keep its lights on and the refrigerator running.

All in all, the average American person reduces the ice cap around the north pole by about 645 square feet (60 square meters) every year. (That’s working from the average U.S. per-capita carbon footprint: about 20 annual tons per capita. If you’re curious, you can estimate your personal carbon footprint using the Nature Conservancy’s calculator.)

The paper is the first to identify a linear relationship between carbon dioxide and Arctic summer sea-ice. That it’s summer ice is crucial, here: The northern ice cap waxes and wanes with the season, receding in the summer and recovering in the winter. Every year, its summer area generally gets smaller and smaller—this year it tied for second-smallest ever—but the nocturnal polar winter allows the ice to post strong recoveries.

This relationship—which is technically 3.0 plus or minus 0.1 square meters per additional ton of carbon—allows the authors to estimate the first year when the Arctic Ocean will lose all of its ice during the summer. They phrase this not in terms of a year, but an amount: When an additional 1,000 gigatons of carbon dioxide are emitted, summer sea ice will vanish.

“At current emissions rates, we will have reached that limit in 25 to 30 years,” says Dirk Notz, an author of the paper and the head of sea-ice research at the Max Planck Institute for Meteorology. “There is not a god-given year, basically, as to when the ice is gone, but it really is this limit of total emissions. So if we emit less, then it will take longer. It’s as simple as that.”

1,000 gigatons is also about how much atmospheric carbon would warm the world by 2 degrees Celsius. Last year, the Paris Agreement set 2 degrees of planetary warming as the maximum amount of climate change that the nations of the world would allow.

“Once we’ve emitted about 1,000 gigatons of CO₂, we’ve reached the two-degree global warming target … and the Arctic is ice free in summer. This suggests the two-degree global-warming target is not sufficient to allow Arctic summer sea ice to survive,” Notz told me.

Notz and the paper’s other author, Julienne Stroeve, analyzed more than 50 years of observational data and a set of global modeling runs for this study. (Notably, they found that the real Arctic Ocean lost ice faster than the models would predict—in other words, existing models are less sensitive to atmospheric carbon than they should be.) In a similar study last year, Notz and Stroeve identified that global mean temperature and Arctic summer sea-ice maintained a linear relationship. This study advances that work by putting it into individual—even pedestrian—terms.