Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Two curious young Polar bears (Ursus maritimus), Barter Island, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Polar bear (Ursus maritimus) adult walking over newly formed pack ice during fall freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Caribou (Rangifer tarandus) pair walking at sunset in the arctic, North Slope of Brooks range, Alaska, USA

Steven Kazlowski / Grizzly bear (Ursus arctos horribils) walking on snow, 1002 coastal plain, Arctic National Wildlife Refuge, North Slope of Brooks Range, Alaska, USA

Steven Kazlowski / Green Aurora borealis over the Beaufort Sea, seen from the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) in the water along the coast of the Beaufort Sea, Bernard Spit, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Portrait of Polar bear (Ursus maritimus) cub along the Bernard Spit during autumn freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) traveling across newly formed pack ice during autumnal freeze up, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska,...

Steven Kazlowski / Arctic fox {Alopex lagopus} hunting rodents under the snow, North Slope, Alaska. Sequence 1/3.

Steven Kazlowski / Arctic fox {Alopex lagopus} hunting rodents under the snow, North Slope, Alaska. Sequence 3/3.

Steven Kazlowski / Arctic fox {Alopex lagopus} hunting rodents under the snow, North Slope, Alaska. Sequence 2/3.

DOC WHITE / Polar bear mother and cubs sliding down slope {Ursus maritimus} Canadian Arctic

Yva Momatiuk & John Eastcott / Arctic Fox (Alopex lagopus) in spring, looking for carrion on sea ice, North Slope near Arctic Ocean, Alaska

Yva Momatiuk & John Eastcott / Arctic Fox (Alopex lagopus) in spring, looking for carrion on sea ice, North Slope near Arctic Ocean, Alaska

Yva Momatiuk & John Eastcott / Arctic Fox (Alopex lagopus) in spring, North Slope, Alaska

Yva Momatiuk & John Eastcott / Muskox (Ovibos moschatus) cow during rutting season, North Slope, Alaska

Yva Momatiuk & John Eastcott / Red Fox (Vulpes vulpes) kit yawning on ridge near den, North Slope, Alaska

Sumio Harada / Mountain Goat (Oreamnos americanus) looking down from rocky, steep mountain slope, Rocky Mountains, North America

Floris van Breugel / Autumn foliage in the North Cascades on a steep slope overlooking a mist filled valley, near the Canadian Border, Washington, USA. September 2012

Oriol Alamany / White Mountain Heather (Cassiope mertensiana) in flower growing on mountain slope in Banff National Park, Rocky Mountains, Alberta, Canada

Steven Kazlowski / Polar bear (Ursus maritimus) pair of adult sows play with one another on the pack ice during fall freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) curious spring cub checks out a local elder in snow vehicle outside the arctic village of Kaktovik, Barter Island, 1002 area of the Arctic National Wildlife Refuge, North...

Steven Kazlowski / Polar bear (Ursus maritimus) adult stands on the snow-covered pack ice to get a better look at something in the distance, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) walks through slushy newly forming pack ice at sunrise, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) pair of adults rest and stay cool on the newly formed pack ice in autumn, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sows with cubs hang out on newly formed pack ice during fall freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play tug-o-war with a piece of whale remains during freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sow on newly formed pack ice with spring cub playing in the water, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) adult resting and staying cool on the newly formed pack ice in autumn, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sow on newly formed pack ice with spring cub playing in the water, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Full moon over Gates of the Arctic National Park, Brooks Range, North Slope, Alaska, USA

Steven Kazlowski / White fronted goose (Anser albifrons) adult walking over a frozen freshwater pond, 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Muskox (Ovibos moschantus) profile of a bull on the central arctic coastal plain, North Slope of the Brooks Range, Alaska, USA

Steven Kazlowski / Wolverine (Gulo gulo) adult scavenging along the 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope of Brooks Range, Alaska, USA

Steven Kazlowski / Full moon over Gates of the Arctic National Park, Brooks Range, North Slope, Alaska, USA

Steven Kazlowski / Reindeer (Rangifer tarandus) adult carcass frozen in the snow at -40 below zero, 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Arctic char (Salvelinus alpinus) catch held by silhouetted woman at sunset, 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) cub plays with a piece of bowhead whale baleen (Balaena mysticetus)along the arctic coast at sunrise, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska...

Mike Potts / Harebells on east slope on Bardsey Island, with a lighthouse in the distance. North Wales, UK, August 2012

Steven Kazlowski / Rock Ptarmigan (Lagopus mutus) adult female camouflaged as its nest in the rocky slope on Primrose Ridge, Mount Margaret, Denali National Park, Interior of Alaska, June.

Steven Kazlowski / Decorated BP truck takes part in the local parade during Piuraagiaqta, Barrow's annual spring whaling festival. North Slope, Alaska, April 2012.

Steven Kazlowski / Male Polar bear (Ursus maritimus) walking on shore along Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, September 2011

Steven Kazlowski / Male Polar bear (Ursus maritimus) resting on shore along Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, September 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Green Aurora borealis over the Beaufort Sea, seen from the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Green Aurora borealis over the Beaufort Sea, seen from the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Three subadult Polar bears (Ursus maritimus) playing in water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing on top of a dead Bowhead whale (Balaena mysticetus) left by Inupiaq subsistence whalers, Barter Island, off the 1002 area of the Arctic National Wildlife Re...

Steven Kazlowski / Snowy owl (Nycttea scandiaca) adult feeding on young Gull prey, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) walking across the snow-covered Bernard Spit, near the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) walking across the snow-covered Bernard Spit, near the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

Steven Kazlowski / Two young Polar bears (Ursus maritimus) during the autumn freeze up, Barter Island, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Polar bear (Ursus maritimus) walking on newly formed pack ice, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Polar bear (Ursus maritimus) in sea off Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, September 2011

Steven Kazlowski / Polar bear (Ursus maritimus) in sea off Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, September 2011

Danny Green / Bighorn Sheep (Ovis canadensis) on rocky slope. Yellowstone, USA, February.

Danny Green / Bighorn Sheep (Ovis canadensis) on rocky slope. Yellowstone, USA, February.

Donald M. Jones / Short-tailed Weasel (Mustela erminea) camouflaged in scree, Denali National Park, Alaska

Donald M. Jones / American Pika (Ochotona princeps) in scree slope, Glacier National Park, Montana

Charlie Summers / Rocky Mountain Goat (Oreamnos americanus) nanny foraging for food under a snow covered slope in the winter. Colorado, USA, February.

Kevin Schafer / Aerial view of crater rim on south slope of Mount St Helens, Mount St Helens National Volcanic Monument, Washington

Bryan and Cherry Alexander / Driftwood from Siberia on North Slope beach. Barrow, Alaska, USA.

Jenny E. Ross / An autumn storm sweeps across the Mono Basin from the east slope of the Sierra Nevada Mountains. Mono Lake, Mono Basin National Forest Scenic Area, October 1997.

Konstantin Mikhailov / Dall sheep (Ovis dalli) male resting on the slope of the canyon, Denali NP, Alaska, USA, North America. September 2009.

Konstantin Mikhailov / Dall sheep (Ovis dalli) male resting on the slope of the canyon, Denali NP, Alaska, USA, North America. September 2009.

Eric Baccega / Arctic fox (Vulpes lagopus) in white phase, sitting on a snow slope, Banks Island, North West Territories, Canada

Thomas Lazar / Pine tree and rock at crest of cracked rock slope, Tioga Pass, Olmsted Point, Sierra Nevada Mountains, Yosemite National Park, California, USA, June 2008

Patricio Robles Gil / Bighorn sheep (Ovis canadensis) ram running down a snow covered slope, Wind River Range, Wyoming, USA, January

Patricio Robles Gil / Bighorn sheep (Ovis canadensis) ram running down snow covered slope, Wind River Range, Wyoming, USA, January

Adrian Davies / Naturalized Rhododendron {Rhododendron ponticum} growing in the wild on scree slope in Snowdonia National Park, North Wales, UK

Mike Potts / Chough (Pyrrhocorax pyrrhocorax) group feeding on cliff slope, searching for invertebrates, South Stack, Anglesey, North Wales, UK

Steven Kazlowski / The oldest Inupiaq village of Point Hope as seen from the pack ice, Lisburne Peninsula, North Slope, along the western Arctic coast of Alaska, April 2008

Steven Kazlowski / American golden plover (Pluvialis dominica) in shallow water along the Arctic coast, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, Summer

Steven Kazlowski / American golden plover (Pluvialis dominica) in shallow water along the Arctic coast, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, Summer

Bruno D'Amicis / Euphorbia / Spurge (Euphorbia officinarum echinus) on rocky slope, Southern Morocco, NW Africa

Bruno D'Amicis / Euphorbia / Spurge (Euphorbia officinarum echinus) growing on rocky slope, Southern Morocco, NW Africa

Bruno D'Amicis / Euphorbia / Spurge (Euphorbia officinarum echinus) growing on rocky slope, Southern Morocco, NW Africa

Thomas Lazar / Trunks of Giant Sequoia trees (Sequoiadendron giganteum) with smaller trees behind, Western Slope Sierra Nevada Mnts, Sequoia National Park, California, USA

Thomas Lazar / Towering trunk of Giant Sequoia tree (Sequoiadendron giganteum) in fog, Western Slope Sierra Nevada Mnts, Sequoia National Park, California, USA

Thomas Lazar / Looking up the trunk of Giant Sequoia tree(Sequoiadendron giganteum) Western Slope Sierra Nevada Mnts, Kings Canyon National Park, California, USA

Thomas Lazar / Towering trunks of Giant Sequoia tree (Sequoiadendron giganteum) in fog, Western Slope Sierra Nevada Mnts, Sequoia National Park, California, USA

Thomas Lazar / Trunks of Giant Sequoia trees (Sequoiadendron giganteum) with smaller trees behind, Western Slope Sierra Nevada Mnts, Sequoia National Park, California, USA

Thomas Lazar / Trunks of Giant Sequoia trees (Sequoiadendron giganteum) with smaller trees behind, Western Slope Sierra Nevada Mnts, Sequoia National Park, California, USA

Thomas Lazar / Towering trunk of Giant Sequoia tree (Sequoiadendron giganteum) in fog, Western Slope Sierra Nevada Mnts, Sequoia National Park, California, USA

Thomas Lazar / Looking up the trunk of Giant Sequoia tree(Sequoiadendron giganteum) Western Slope Sierra Nevada Mnts, Kings Canyon National Park, California, USA. Did you know? Sequoias were named after Sequoyah, th...