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

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

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

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

Ross Hoddinott / Ice on black volcanic sand beach with waves, Jokulsarlon, Southeast Iceland, February.

Ole Jorgen Liodden / Ice cliff of the Austfonna ice cap with melt water and ice crashing down to the sea, Svalbard, Norway, July 2012.

Ole Jorgen Liodden / Polar bear (Ursus maritimus) walking across vast ice floe, Spitsbergen, Svalbard, July 2013.

Christophe Courteau / Iceberg, Spitzbergen, Norway, June, 2012.

Orsolya Haarberg / Arctic tern (Sterna paradisaea), adult feeding young. Jokulsarlon glacial lagoon. Iceland. August 2008

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) juvenile spreading body weight over thin newly forming pack ice, trying not to break through, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North...

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) juvenile rolling around on newly formed pack ice, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) curious adult head underwater, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska.