Study links human behavior with shrinking Arctic sea ice

WASHINGTON — Driving a gas-powered car about 90 miles — the distance between New York and Philadelphia — melts about a square foot of Arctic sea ice in the critical month of September, according to a new study that directly links carbon pollution to the amount of ice that’s thawing.

At current carbon emission levels, the Arctic will likely be free of sea ice in September around midcentury, which could make weather even more extreme and strand some polar animals, a study published Thursday in the journal Science finds.

The study calculates that for every ton of carbon dioxide put in the air, there’s 29 square feet less of sea ice (for every metric ton, there’s 3 square meters less) during the crucial month when the Arctic region is least frozen.

Using observations, statistics and 30 different computer models, the study authors show heat-trapping gases cause warming and the melting of sea ice in a way that can be translated into a simple mathematical formula.

There’s “a very clear linear relationship” between carbon dioxide emissions and sea ice retreat in September, especially at the southern boundary edges, said study lead author Dirk Notz, a climate scientist at Max Planck Institute for Meteorology in Germany.

“It’s very simple. Those emissions from our tailpipes and our coal-fired power plants are all going into the atmosphere,” said study coauthor Julienne Stroeve, a climate scientist at both the National Snow and Ice Data Center in Boulder, Colorado, and University College, London.