Sea ice is frozen ocean water that melts each summer, then refreezes each winter.

Sea ice affects Arctic communities and wildlife such as polar bears and walruses.

As the climate changes, the Arctic is warming more than twice as fast as the rest of the planet.

The Arctic Ocean will be ice-free in the summer within the next 30 years, a study says, which will result in "devastating consequences for the Arctic ecosystem," according to McGill University in Montreal.

Sea ice is frozen ocean water that melts each summer, then refreezes each winter. The amount of summer sea ice in the Arctic has been steadily shrinking over the past few decades because of global warming. Since satellite records began in 1979, summer Arctic ice has lost 40% of its area and up to 70% of its volume, the Guardian said.

In fact, it reached its second-smallest level on record in 2019, the National Oceanic and Atmospheric Administration said.

Sea ice affects Arctic communities and wildlife such as polar bears and walruses, and it helps regulate the planet’s temperature by influencing the circulation of the atmosphere and ocean. It also affects global weather patterns.

"While the Arctic sea ice extent is decreasing during this transition to an ice-free Arctic, the year-to-year variability in extent greatly increases, making life more difficult for local populations and ice-dependent species," said study co-author Bruno Tremblay of the department of atmospheric and oceanic sciences at McGill.

'Polar bears may disappear': Arctic sea ice keeps shrinking. Here's what that means for the planet

As the climate changes, the Arctic is warming more than twice as fast as the rest of the planet. Arctic air temperatures were about 3.4 degrees above average in 2019 and were the second-warmest since records began in 1900.

How often the Arctic loses its sea ice cover in the future depends on emissions of carbon dioxide, the study said. If emissions are reduced rapidly, ice-free years will occur only occasionally. With higher emissions, the Arctic Ocean will become ice-free in most years.

Thus, even if humans act to reduce emissions dramatically, summer sea ice might still be gone, according to the study.

Sea ice melting:Rising Arctic temps cause sea ice to melt at alarming level, threatening habitats and cultures

"If we reduce global emissions rapidly and substantially, and thus keep global warming below 2 degrees Celsius relative to pre-industrial levels, Arctic sea ice will nevertheless likely disappear occasionally in summer even before 2050," said study lead author Dirk Notz, who heads the sea ice research group at the University of Hamburg in Germany. "This really surprised us."

The study analyzed recent results from 40 of the latest climate computer models and involved 21 research institutes from around the world. It was published in the journal Geophysical Research Letters, a publication of the American Geophysical Union.