Steven Kazlowski / Polar bear (Ursus maritimus) silhouetted against setting sun, Bernard Spit, off the 1002 Area, Arctic National Wildlife Refuge, North Slope, Alaska, USA, October. Vulnerable species.

Steven Kazlowski / Polar bear (Ursus maritimus) portrait against sky at sunset, Bernard Spit, off the 1002 Area, Arctic National Wildlife Refuge, North Slope, Alaska, USA, September. Vulnerable species.

Pal Hermansen / Puffin (Fratercula arctica) close up portrait, Iceland, June.

Pal Hermansen / One-year ice off Ellesmere island, Nunavut, Canada, August.

Sergey Gorshkov / Arctic fox (Alopex lagopus) juveniles play fighting, Wrangel Island, Far East Russia, August.

Orsolya Haarberg / Snow covered Norway spruce (Picea abies) trees at the treeline, Stubba Nature Reserve, Laponia, Sweden, February 2013.

Erlend Haarberg / Norway spruce trees (Picea abies) covered in snow and frost, at sunrise, Mellan-Stubba, Stubba Nature Reserve, Lapland, Sweden, February 2013.

Erlend Haarberg / Rock face reflected in lake surface with floating blue ice sheets, Ovre Pikhaugvatnet lake, Glomdalen valley, Saltfjellet-Svartisen National Park, Norway, August 2015.

Erlend Haarberg / Woman pulling a sledge up a slope, Rapadalen, Sarek National Park, Laponia, Sweden, March 2015.

Erlend Haarberg / Photographer silhouetted on Mt Luottotjakka overlooking the Arjep Luottojekna and Nuortap glaciers at sunset, Sarek National Park, World Heritage Laponia, Swedish Lapland, Sweden, August 2013.

Benjamin Barthelemy / Long exposure of tidal water flowing off rocks, with the Okshornan Mountains in the background, Isle of Senja, Troms, Norway, February 2015.

Wild Wonders of Europe / Widstrand / Humpback whale (Megaptera novaeangliae) tail fluke above water before diving, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on the large numbers of sp...

Wild Wonders of Europe / Widstrand / Humpback whale (Megaptera novaeangliae) tail fluke above water before diving, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on the large numbers of sp...

Wild Wonders of Europe / Widstrand / Orca / Killer whale (Orcinus orca) surfacing, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on the large numbers of spawning Herring fish

Wild Wonders of Europe / Widstrand / Dorsal fin of Orca / Killer whale (Orcinus orca) surfacing, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on the large numbers of spawning Herring fis...

Brent Stephenson / Type B Killer whale (Orca orcinus) surfacing, close-up, Antarctic Sound, Antarctic Peninsula, Antarctic, January.

Brent Stephenson / Humpback whale (Megaptera novaeangliae) surfacing whilst lunge-feeding, showing the extended throat pleats, Neko Harbour, Antarctic Peninsula, Antarctica, January.

Brent Stephenson / Sunset off Scott Island, with floating pieces of sea ice, Scott Inlet, Baffin Island, Canadian Arctic, August 2015.

Brent Stephenson / Polar bear (Ursus maritimus) mother and large second year cub swim across calm water, Scott Inlet, Baffin Island, Canadian Arctic, August. Vulnerable species.

Brent Stephenson / Young Polar bear (Ursus maritimus) walking across melting sea ice, Scott Inlet, Baffin Island, Canadian Arctic, August. Vulnerable species.

Brent Stephenson / Male Polar bear (Ursus maritimus) feeding on a first year Polar bear cub it has just killed, Scott Inlet, Baffin Island, Canadian Arctic, August. Vulnerable species.

Brent Stephenson / Male Polar bear (Ursus maritimus) feeding on a first year Polar bear cub it has just killed, Scott Inlet, Baffin Island, Canadian Arctic, August. Vulnerable species.

Tui De Roy / Adelie penguin (Pygoscelis adeliae) courtship behaviour. Prydz Bay, near Davis Station, Vestfold Hills, Ingrid Christensen Coast, East Antarctica, November.

Tui De Roy / Emperor penguin (Aptenodytes forsteri) chicks, Amanda Bay, Prydz Bay, Ingrid Christensen Coast, East Antarctica, November.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans) flying off coast of South Georgia Island.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / King penguin (Aptenodytes patagonicus) colony with storm approaching. Grytviken, South Georgia Island.

Chris & Monique Fallows / King penguin (Aptenodytes patagonicus) and Southern elephant seal (Mirounga leonina) colony at sunrise. Grytviken, South Georgia Island.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), in flight over South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans) flying off coast of South Georgia Island. Silhouetted.

Chris & Monique Fallows / King penguin (Aptenodytes patagonicus) group on ice preparing to dive. South Georgia Island.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), feeding and cleaning.

Erlend Haarberg / Arctic fox (Alopex lagopus) silhouetted against stormy sky, Dovrefjell-Sunndalsfjella National Park, Norway, July.

Erlend Haarberg / Arctic fox (Alopex lagopus) cubs playing, Dovrefjell-Sunndalsfjella National Park, Norway, July.

Erlend Haarberg / Arctic fox (Alopex lagopus) cub sitting,rear view, Dovrefjell-Sunndalsfjella National Park, Norway, July.

Erlend Haarberg / Arctic fox (Alopex lagopus) adult barking on rocks, Dovrefjell-Sunndalsfjella National Park, Norway, July.

Erlend Haarberg / Arctic fox (Alopex lagopus) cubs looking curiously, Dovrefjell-Sunndalsfjella National Park, Norway, July.

Fred Olivier / Adelie penguins (Pygoscelis adeliae) in front of French Icebreaker L'Astrolabe, on edge of the fast ice off Dumont D'Urville station, Antarctica. December 2014.

Ole Jorgen Liodden / Polar bear (Ursus maritimus) standing on ice floe, looking at camera. Svalbard, Norway. August.

Sven Zacek / Walruses (Odobenus rosmarus) fighting over a resting place on snow, Magdalenefjorden Fjord, Svalbard, Spitsbergen, Norway, June.

Sven Zacek / Walrus (Odobenus rosmarus) swimming towards a camera, Magdalenefjorden Fjord, Svalbard, Spitsbergen, Norway. June.

Danny Green / Polar bear (Ursus maritimus) cub playing with branch,Churchill, Canada, November

Charlie Summers / Adelie Penguin (Pygoscelis adeliae) carrying stolen rock from another nest in rookery, Peterman Island, Antarctica, November.

Espen Bergersen / Two Svalbard reindeer (Rangifer tarandus platyrhychus) Svalbard, Norway, April.

Uri Golman / Svalbard reindeer (Rangifer tarandus platyrhynchus) in velvet, resting, Svalbard, Norway, August.

Espen Bergersen / Svalbard reindeer (Rangifer tarandus platyrhynchus) in distance at sunset, Svalbard, Norway. April.

Richard Kirby / Svalbard reindeer (Rangifer tarandus platyrhynchus) mother and calves, Svalbard, Norway, February.

Jenny E. Ross / Svalbard reindeer (Rangifer tarandus platyrhynchus) jumping across a narrow gully, Eidembukta, Spitsbergen, Svalbard, Norway. August.

Espen Bergersen / Svalbard reindeer (Rangifer tarandus platyrhynchus) rear view lying down, resting at sunset, Svalbard, Norway. April.

Jordi Chias / Atolla jellyfish (Atolla wyvillei) with Gentoo penguin (Pygoscelis papua) in the background near the surface. Antarctic Peninsula. Finalist in the Underwater category of the Wildlife Photographer of t...

Sven Zacek / Eider ducks (Somateria mollissima) males reflected in a small pond, Longyearbyen, Svalbard, Norway. June.

Sven Zacek / View through glacier ice towards snow-covered mountains in Kongsfjorden fjord in Svalbard, Norway. June 2015.

Franco Banfi / Walrus (Odobenus rosmarus) two swimming underwater, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Franco Banfi / Walrus (Odobenus rosmarus) two swimming underwater, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Franco Banfi / Walrus (Odobenus rosmarus) swimming underwater, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Franco Banfi / Walrus (Odobenus rosmarus) Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Franco Banfi / Walrus (Odobenus rosmarus) hauled out in shallow water, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Franco Banfi / Walrus (Odobenus rosmarus) male and female, hauled out in shallow water, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Steven Kazlowski / Polar bear (Ursus maritimus) curious young bear approaches over newly forming pack ice during autumn freeze up, Beaufort Sea, off Arctic coast, Alaska

Erlend Haarberg / Arctic fox (Alopex lagopus) cubs looking curiously, Dovrefjell-Sunndalsfjella National Park, Norway, July.

Staffan Widstrand / Bearded seal (Erignathus barbatus) hauled out on ice, Spitsbergen, Svalbard, Norway, September.

Staffan Widstrand / Arctic fox (Vulpes lagopus) in winter coat, resting in grass, Spitsbergen, Svalbard, Norway, September.

Staffan Widstrand / Arctic fox (Vulpes lagopus) in winter coat, sitting, Spitsbergen, Svalbard, Norway, September

Staffan Widstrand / Svalbard reindeer (Rangifer tarandus platyrhynchus) with bloody antlers shedding velvet, Spitsbergen, Svalbard, Norway, September

Staffan Widstrand / Two Svalbard reindeer (Rangifer tarandus platyrhynchus) fighting; antlers shedding velvet; Spitsbergen, Svalbard, Norway, September

Staffan Widstrand / White Arctic fox (Alopex lagopus) in its winter fur looking at the camera, Svalbard, Norway, Arctic, September

Staffan Widstrand / Dead Polar bear (Ursus maritimus) starved to death, Zeipelodden, Svalbard, Norway, September.

Staffan Widstrand / Atlantic Walrus (Odobenus rosmarus) at surface, Svalbard, Norway, Arctic, September

Andy Rouse / Chinstrap penguin (Pygoscelis antarcticus) group on blue iceberg, Antarctica

Andy Trowbridge / Arctic fox (Alopex / Vulpes lagopus) stalking / hunting silhouetted against a colourful sky at sunset. Dovrefjell National Park, Norway, September.

Steven Kazlowski / Photographer in front of Northern lights / Aurora borealis glowing brightly over the frozen eastern Beaufort Sea, Arctic National Wildlife Refuge, Alaska Model released.

Steven Kazlowski / Polar bear (Ursus maritimus) curious young bear approaching camera, over newly forming pack ice during autumn freeze up, Beaufort Sea, off Arctic coast, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) young bear rolling around in the snow, on newly formed pack ice during autumn freeze up, Beaufort Sea, off Arctic coast, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) juvenile crossing over newly forming pack ice, during autumn freeze up, Beaufort Sea, off Arctic coast, Alaska

Roy Mangersnes / Full moon over Adventsdlen, Longyearbyen, Svalbard, Norway, April.

Roy Mangersnes / Polar bears (Ursus maritimus) courting on ocean ice north of Spitsbergen, Svalbard, Norway, July.

Ole Jorgen Liodden / Svalbard reindeer (Rangifer tarandus platyrhyncus) feeding at sunset, Spitsbergen, Svalbard, Norway, April.

Ole Jorgen Liodden / Polar bear (Ursus maritimus) footprints in snow, on cracked ice, Svalbard, Norway, September.

Ole Jorgen Liodden / Polar bear (Ursus maritimus) stranded on island, with full moon above, north of Nordaustlandet, Svalbard, Norway, September.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / King penguin (Aptenodytes patagonicus) colony at sunrise. Grytviken, South Georgia Island.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), feeding and cleaning.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), feeding and cleaning.

Chris & Monique Fallows / Wandering albatross, (Diomedea exulans), fighting for fish scraps.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), feeding and cleaning.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Todd Mintz / Polar bear (Ursus maritimus) cub at entrance to den, Manitoba, Canada. March.

Ole Jorgen Liodden / Landscape of Lillehooksbreen glacier at Svalbard, Norway, July 2008.