Roland Seitre / Polar Wolves (Canis lupus arctos), a high arctic variant of the Grey Wolf. Captive. Lobo Park, Antequera, Spain, January.

Ole Jorgen Liodden / Polar Bear (Ursus maritimus) looking across ice floe seascape. Nordaustlandet, Svalbard, August.

Jeff Wilson / Pyramid of sea ice catching the first rays of the returning sun in the high Arctic, Svalbard, Spitsbergen, Norway, February 2009. Taken on location for the BBC series, Frozen Planet.

Jeff Wilson / Pyramid of sea ice catching the first rays of the returning sun in the high Arctic, Svalbard, Spitsbergen, Norway, February 2009. Taken on location for the BBC series, Frozen Planet.

Jeff Wilson / Pyramid of sea ice catching the first rays of the returning sun in the high Arctic, Svalbard, Spitsbergen, Norway, February 2009. Taken on location for the BBC series, Frozen Planet.

Jeff Wilson / Crew member of the US coastguard ship 'Healy' standing on the sea ice in front of the ship's hull after the ship became stuck in the ice, Bering Sea, Alaska, USA, March 2008. Taken on location for the...

Sue Flood / Russian Icebreaker, NS 50 Lyet Pobyedi (50 Years of Victory) approaching Rubini Rock, bird colony, Tikhaya Bukhta, Franz Josef Land, Russian Arctic, July 2008

Andy Rouse / Walrus (Odobenus rosmarus) pair on ice in landscape, Svalbard, Norway

Andy Rouse / Polar bear (Ursus maritimus) standing up against tourist ship, Svalbard, Norway, June 2009

Andy Rouse / Polar bear (Ursus maritimus) standing up against tourist ship, Svalbard, Norway, June 2009

Michael Pitts / Kittiwake {Rissa tridactyla} flying over arctic ice cap

Sue Flood / Aerial view of sea ice floe breaking up in summer, Admiralty Inlet, Canadian High Arctic, June 2000

Staffan Widstrand / High arctic landscape in spring, -40 degrees C, Bylot Is, Baffin Is, North West Territories, Canada, 1995

Jim Brandenburg / Arctic Wolf (Canis lupus) pack hunting Muskox (Ovibos moschatus) herd, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Polar Bear (Ursus maritimus) walking across ice floes, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) alpha male known as Buster, smelling Arctic Poppy (Papaver lapponicum) flowers, Ellesmere Island, Nunavut, Canada

Thomas Mangelsen / Arctic Fox (Alopex lagopus) curled up resting in snow, Hudson Bay, near Churchill, Manitoba, Canada

Michio Hoshino / Caribou (Rangifer tarandus) herd, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) herd migrating in summer, Arctic National Wildlife Refuge, Alaska

Jim Brandenburg / Polar Bear (Ursus maritimus) running over icefield during spring thaw, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Polar Bear (Ursus maritimus) walking on ice floe, Ellesmere Island, Nunavut, Canada

Flip Nicklin / Brittle Star, Admiralty Inlet, Baffin Island, Canada

Tui De Roy / Polar Bear (Ursus maritimus) hunting on summer fjord ice, Spitsbergen, Svalbard, Norwegian Arctic

Tui De Roy / Bearded Seal (Erignathus barbatus) resting on ice floe near Wagon Way Glacier, Magdalenefjorden, Spitsbergen, Svalbard, Norwegian Arctic

Flip Nicklin / Bearded Seal (Erignathus barbatus) male resting on ice floe with head dyed red from the high iron content of ocean mud in which he hunts for shrimp and clams, Svalbard, arctic Norway

Flip Nicklin / Ringed Seal (Phoca hispida) at breathing hole, Arctic

Jim Brandenburg / Arctic Hare (Lepus arcticus) babies camouflaged on tundra, Ellesmere Island, Nunavut, Canada

Sue Flood / Beluga whales caught in ice hole wounded from Polar bear attack. Canadian high arctic. June 1999

Sue Flood / Beluga whales trapped at ice hole {Delphinapterus leucas} too far away to reach open sea, Canadian High Arctic. June 1999

Rob Brown / Tourists admiring Dettifoss Waterfall, Vatnajokull National Park, Iceland

Rob Jordan / 2020VISION / Arctic tern (Sterna paradisaea) in flight flashed against white sky to accentuate high-key light of white-on-white, Inner Farne, Farne Islands, Northumberland, July 2011.

Rob Jordan / 2020VISION / Arctic tern (Sterna paradisaea) in flight flashed against white sky to accentuate high-key light of white-on-white, Inner Farne, Farne Islands, Northumberland, July 2011.

Erlend Haarberg / View from Storfjellet of Hernyken and Trenyken, Rost, Lofoten, Norway, June 2006

Roland Seitre / Polar Wolf (Canis lupus arctos), a high arctic variant of the Grey Wolf, portrait. Captive. Lobo Park, Antequera, Spain, January.

Roland Seitre / Polar Wolf (Canis lupus arctos), a high arctic variant of the Grey Wolf, yawning. Captive. Lobo Park, Antequera, Spain, January.

Roland Seitre / Polar Wolf (Canis lupus arctos), a high arctic variant of the Grey Wolf, resting on flower meadow. Captive. Lobo Park, Antequera, Spain, January.

Steven Kazlowski / Fish eye view of a steel hull sailboat from the crow's nest, Spitsbergen, Svalbard Archipelago, Norway, July 2011

Jeff Wilson / The sun returns for the first time to Svalbard, Norway, in the High Arctic after an absence of six months during the Arctic winter, February 2009. Taken on location for the BBC series, Frozen Planet.

Jeff Wilson / Sea ice forming in the Bering Sea, Alaska, USA, in March 2008. Taken on location for the BBC series, Frozen Planet.

Jeff Wilson / The crew of United States Coastguard Cutter 'Healy' prepare decks in the Bering sea, Alaska, USA. The ship served as a platform for the Frozen Planet crew whilst filming Spectacled eider ducks overwin...

Jeff Wilson / Aerial view of science teams and Frozen Planet film crew working on the sea ice in the Bering Sea, Alaska, USA, March 2008. The film crew were in search of Spectacled eider ducks, temperatures rarely...

Bryan and Cherry Alexander / "Professor Mulchanov" in Magdalene Fjord on a fine day with altostratus clouds. Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Ice-breaker "Professor Mulchanov" in Magdalene Fjord with altostratus clouds above. Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Photographers on the bow of the "Professor Mulchanov" photograph a Polar bear (Ursus maritimus) feeding on a dead bearded seal. Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Tourists walking in deep snow high above Tinayre Bukta, Krossfjorden. Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Walkers resting on a ridge of moss covered tundra high above Tinayre Bukta, Krossfjorden, Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Photographers on the Professor Mulchanov taking pictures of a Bearded seal (Erignathus barbatus) on an ice floe. Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Tourists on the bow of the "Professor Mulchanov" looking for wildlife. Hymebreen, Hornsund Fjord, Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Tourists on the bow of the "Professor Mulchanov" looking for wildlife. Hymebreen, Hornsund Fjord, Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Passengers on Icebreaker "Professor Mulchanov" looking for wildlife in Brepollen. Hornsund, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Woman breaking rocks to look for fossils high on the moraine to Longyearbreen above Longyearbyen. Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Young Selkup fishermen unloading their catch at Bistrinka. Purovsky Region, Yamal, Western Siberia, Russia, August 2008. Editorial use only.

David Woodfall / Male Polar bears (Ursus maritimus) two asleep in day snow beds, Wapusk National Park, Churchill, Manitoba, Canada, December 2004

Bryan and Cherry Alexander / A welder working in the gas fields at Sabetta near Tambey, Yamal Peninsula, Western Siberia, Russia, March 2011

Bryan and Cherry Alexander / A herd of reindeer being gathered at their winter pastures on the tundra near Tambey. Yamal Peninsula, Western Siberia, Russia, March 2011

Bryan and Cherry Alexander / A herd of Reindeer (Rangifer tarandus) being gathered at their winter pastures on the tundra near Tambey. Yamal Peninsula, Western Siberia, Russia, March 2011

Troels Jacobsen/Arcticphoto / Polar Bear (Ursus maritimus) on sea ice with her reflection in a melt pool. 82 degrees north, north of Seven Islands, Polar Basin, Svalbard, 2006.

Orsolya Haarberg / The view of Donna and Heroy from the top of Donnamannen, Helgeland, Nordland, Norway, July 2009

Orsolya Haarberg / The view of the Norwegian strandflat (Helgeland Archipelago) from the Donnamannen, Donna, Helgeland, Nordland, Norway, July 2009

Bryan and Cherry Alexander / View across main street in the town of Nadym, Western Siberia, Russia, 1997.

Bryan and Cherry Alexander / Nenets girl helping to herd Reindeer / Caribou (Rangifer tarandus) at a corral. Yamal, Siberia, Russia, 1993.

Roger Powell / Oystercatcher (Haematopus ostralegus) incubating in a "nest box" placed in a bay of Porsanger fjord. These nest boxes were originally used to provide a supply of eggs for food to local inhabitants, bu...

Bryan and Cherry Alexander / Regional capital city Petropavlovsk with Avachinskij Volcano beyond. Kamchatka, Siberia, Russia, 1999.

Bryan and Cherry Alexander / Bow of Russian icebreaker "Kapitan Dranitsyn" cutting through sea ice. Franz Josef Land, Russia, 2004.

Bryan and Cherry Alexander / Bow of Russian icebreaker "Kapitan Dranitsyn" cutting through sea ice. Franz Josef Land, Russia, 2004.

Bryan and Cherry Alexander / View across the city of Magadan. Eastern Siberia, Russia, 2006.

Bryan and Cherry Alexander / Regional capital city Petropavlovsk with Avachinskij Volcano beyond. Kamchatka, Siberia, Russia, 1999.

Bryan and Cherry Alexander / Russian MI-2 helicopter manoeuvring after taking off from "Kapitan Dranistsyn" Icebreaker. Franz Josef Land, Russia, 2004.

Bryan and Cherry Alexander / Table of traditional North Greenlandic foods: Greenland Halibut, Mattaq (Narwhal skin), eider duck eggs, dried narwhal meat, Arctic char, boiled seal meat & dried polar cod, Thule, Northwest Greenlan...

Bryan and Cherry Alexander / Inuit trimming Narwhal (Monodon monoceros) meat for drying on meat rack. Qaanaaq, Northwest Greenland.

Bryan and Cherry Alexander / Russian Nuclear Icebreaker "Sovetskiy Soyuz" approaching tabular Iceberg in Tichaja Buchta. Franz Josef Land, 1998.

Kevin Schafer / Humpback Whale (Megaptera novaeangliae) diving, Hinlopen Strait, Svalbard, Norway

Bryan and Cherry Alexander / American arctic lemming (Dicrostonyx groenlandicus) on Arctic Tundra. Baffin Island, Nunavut, Canada.

Bryan and Cherry Alexander / Warning sign for high levels of PCBs at an old DEW line station. Melville Peninsula, Nunavut, Canada, 1992.

Sue Flood / Aerial view of Beluga whales (Delphinapterus leucas) Lancaster Sound, Nunavut, Canadian high Arctic, June

Sue Flood / Post office, Craig Harbour, Ellesmere Island, Nunavut, Canadian High Arctic, May 2008

Sue Flood / Aerial view of broken ice on route to the North Pole, Russian Arctic, July 2008

Sue Flood / Photographer Sue Flood with Walrus on ice floe in distance, Igloolik, Nunavut, Canadian high Arctic, June 2004

Sue Flood / Dead Polar bear (Ursus maritimus) which has starved to death, Lancaster Sound, Nunavut, Canadian high Arctic

Sue Flood / Hunter from Greenland in traditional animal skin clothing, including polar bear trousers, creeping up on a sleeping seal, using a traditional hunting technique, near Resolute, Nunavut, Canadian high A...

Sue Flood / Inuit women in traditional caribou clothing and sealskin boots / kamiks, Lancaster Sound, Nunavut, Canadian high Arctic, March 2004

Sue Flood / Polar bear (Ursus maritimus) on ice, Arctic Ocean, July

Doug Allan / Sue Flood on sea ice during filming for the BBC tv series Blue Planet, Lancaster Sound, Canadian high Arctic

Doug Allan / Camping on location on sea ice during filming for BBC series The Blue Planet, Lancaster Sound, Canadian high Arctic, early July 2004

Doug Allan / Aerial view of Beluga whales (Delphinapterus leucas) travelling up lead, Lancaster Sound, Nunavut, Canadian high Arctic

Doug Allan / Inuit hunters with body of unborn Beluga (Delphinapterus leucas) calf and mother that they have hunted, Lancaster Sound, Nunavut, Canadian high Arctic, June 2004

Doug Allan / Man pulling sledge during filming for polar bear sequence of BBC tv series Planet Earth, Kong Karls Land, Svalbard archipelago, Norwegian high Arctic

Steven Kazlowski / Three Polar bears (Ursus maritimus) in rocky landscape, female on the right wearing tracking collar, Svalbard, Norway

Steven Kazlowski / Arctic tern (Sterna paradisaea) newborn chick in nest next to unhatched egg, Longyearbyen, Svalbard, Norway

Steven Kazlowski / Brunnich's guillemot (Uria lomvia) adults surrounding young chicks nesting along cliffs as protection, Sassenfjorden, Svalbard, Norway

David Woodfall / Newly hatched Arctic tern (Sterna paradisaea) chick with unhatched egg in nest, Northumberland, UK

Nick Garbutt / Nest with four eggs of Purple Sandpiper (Calidris maritima) on tundra, Svalbard, High Arctic, Norway

Andy Rouse / Polar bear (Ursus maritimus) standing up against tourist ship, Svalbard, Norway, June 2009

Oriol Alamany / Tufted puffin (Fratercula / Lunda cirrhata) sitting on rock, Saint Paul Island, Pribilof Islands, Alaska, USA

Oriol Alamany / Northern fur seal (Callorhinus ursinus) male with females and pups, Saint George Island, Pribilof Islands, Alaska, USA