
Sea ice in the Arctic Ocean is shrinking fast. But what does that look like? (Pictured: Climate journalist and adventurer Bernice Notenboom negotiating sea ice in the Arctic, photographed by Martin Hartley in 2014.)

British polar explorer Ann Daniels negotiating unstable sea ice during a 2009 Arctic expedition. Hartley, who has been exploring the Arctic Ocean since 2002, says his next project is called "The Last Ice Sentinels."

Daniels swimming between ice floes on her way to the Geographic North Pole in 2010.

Canadian Inuit hunter Jimmy Kulak from Resolute Bay, Cornwallis Island photographed by Hartley in 2011. Hartley says many of his Arctic trips pass through indigenous communities to reach the Arctic Ocean. "They all say the same thing, which is the winters are shorter and a lot warmer," he says.

Fissures in sea ice north of Ellsmere Island, northern Canada in 2017.

A self-portrait of Martin Hartley with frostbite on his nose. The British photographer has endured numerous dangerous experiences in the Arctic when weather conditions have deteriorated, or help has been unavailable.

Esther Horvath is currently drifting through the Arctic Ocean as part of the MOSAiC expedition, a multinational scientific mission attempting to measure changes in the Arctic.

Scientists Gunnar Spreen and Matthew Shupe drill into sea ice on September 30 with the MOSAiC expedition vessel Polarstern in the back on shot.

A polar bear and her cub spotted close to the Polarstern on October 4. The expedition is traveling with designated polar bear guards who stand sentry while scientists work on the ice.

Two polar bears photographed by Horvath at night on October 10. The animals were close to the ship and crew scared them away with the bang of a flare gun, for the safety of crew and the bears.

A Leibniz Institute for Tropospheric Research team member operating a helium-filled balloon in Greenland, 2018.

Field training for the expedition included sea survival training in Ny-Alesund, Svalbard in April this year.

Hungarian photographer Esther Horvath has been documenting Arctic Ocean sea ice since 2015. "We live in a time where ... this environment (is) changing so fast, that if you don't do something now it will completely disappear," she says.

Delbert Pungowiyi, president of the Native Village of Savoonga on St Lawrence Island, part of Alaska in the Bering Strait. Pungowiyi is one of the subjects of Maya Craig's upcoming documentary about how a changing Arctic Ocean is affecting those living and working on its borders.

Crew on deck of the USCG Healy, stationed at Unalaska in the Aleutian Islands, Alaska. The Healy is the only US icebreaker currently operating in the northern hemisphere, and Craig spent time aboard earlier this year with close access to the crew.

As icebreakers are used to help ships navigate an increasingly open Arctic Ocean, these ships will have a crucial role in the years to come.

Craig says her documentary will take more than a year to film and says she has plans to visit the Russian Arctic and the Northwest Passage (a route between the Atlantic Ocean and the Pacific Ocean around the top of continental North America). "The Arctic feels very remote," she says, "but what's happening in the Arctic is impacting everyone, everywhere."