Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight feeding on Spiral Ginger (Costus Pulverulentus), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, female in flight on flower of the ginger family(Zingiberaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight on flower of the ginger family(Zingiberaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight on Heliconia flower, Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight on flower of the ginger family(Zingiberaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight feeding on Shrimp plant(Acanthaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight feeding on Spiral Ginger (Costus Pulverulentus), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, female in flight on flower of the ginger family(Zingiberaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight on flower of the ginger family(Zingiberaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight on Heliconia flower, Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight on flower of the ginger family(Zingiberaceae), Central Valley, Costa Rica, Central America, December 2006

Rolf Nussbaumer / Coppery-headed Emerald, Elvira cupreiceps, male in flight feeding on Shrimp plant(Acanthaceae), Central Valley, Costa Rica, Central America, December 2006

Eric Dragesco / Wild Snow leopard (Uncia uncia) climbing among rocks on a mountainside, Altai Mountains, Mongolia, August.

Eric Dragesco / Wild Snow leopard (Uncia uncia) climbing among rocks on a mountainside, Altai Mountains, Mongolia, August.

Francois Savigny / Polar bear and cub asleep on drifting iceberg, summer, Svalbard, Norway

Arne Hodalic / Nenet herdsman with Reindeer (Rangifer tarandus) during summer migration, Yamal Peninsula, Russia. May.

Jussi Murtosaari / Apollo butterfly (Parnassius apollo) in flight, Foglo, Ahvenanmaa / Aland Islands, Finland, July.

Markus Varesvuo / Guillemot (Uria aalge) flock in flight over nesting colony on rocks, Norway, July 2008

Markus Varesvuo / Temminck's Stint (Calidris temminckii), adult with summer plumage in flight. Norway. June.

Sergey Gorshkov / Arctic fox (Vulpes lagopus) with Snow goose egg in mouth, mid moult from winter to summer fur, Wrangel Island, Far Eastern Russia.

Sergey Gorshkov / Arctic fox (Vulpes lagopus) with Snow goose egg in mouth, mid moult from winter to summer fur, Wrangel Island, Far Eastern Russia, June.

Sergey Gorshkov / Arctic fox (Vulpes lagopus) with Snow goose egg in mouth, mid moult from winter to summer fur, Wrangel Island, Far Eastern Russia, June.

Andy Trowbridge / Arctic Fox (Alopex / Vulpes lagopus) standing on ridge, during moult from grey summer fur to winter white. Dovrefjell National Park, Norway, September.

Andy Trowbridge / Arctic Fox (Alopex / Vulpes lagopus) hunting in fresh snow, during moult from grey summer fur to winter white. Dovrefjell National Park, Norway, September.

Orsolya Haarberg,Orsolya Haarberg / Rhiolite mountains. Landmannalaugar, Iceland. June 2008

Eric Baccega / Aerial view of Devon Island, Nunavut, Canada, June 2012.

Steven Kazlowski / Polar bear (Ursus maritimus) curious adult investigates a remote camera along a hillside on Spitsbergen and the northwest coast of the Svalbard Archipelago, Norway, Greenland Sea, July

Kirkendall-Spring / Meadow flowers blooming on Mazama Ridge in Mount Rainier National Park with the Tatoosh Range in the distance, Washington, USA, August 2009

Jeff Wilson / Royal Navy helicopter from HMS Endurance flying over sea and antarctic landscape, November 2008, Taken on location for the BBC series, Frozen Planet.

Inaki Relanzon / Iceberg against a blue sky. Ilulisat, West Greenland, summer.

Floris van Breugel / Early summer morning, clearing mist reveals Mt. Rainier, with summer alpine blooms on the shores of lake, Rainier National Park, Washington, USA, June 2008.

Bryan and Cherry Alexander / Inuit hunter untangling team of Huskies (Canis familiaris) in front of iceberg. Savissivik, Northwest Greenland, 1997.

Steven Kazlowski / Thousands of Snow geese (Chen caerulescens) taking flight to begin their migration south from their summer nesting grounds in the Arctic, Alaska.

Gerrit Vyn / Willow Ptarmigan (Lagopus lagopus) male standing on snow covered ground, vocalising in spring courtship. Males retain the white body plumage of winter plumage and molt the head and neck feathers to th...

Aflo / N-20904 Cattle grazing in alpine meadow with snow capped mountains in distance, the Alps, France.

David Tipling / Lenticular clouds over the mountains bordering Gold Harbour, South Georgia, November 2006

Steven Kazlowski / Pair of Arctic foxes (Vulpes / Alopex lagopus) one adult in its winter coat and one pup in its summer coat, play vigorously on the pack ice, 1002 area of the Arctic National Wildlife Refuge, Alaska, O...

Steven Kazlowski / Young Arctic fox (Vulpes / Alopex lagopus) its coat turning from summer brown to winter white, walking along the Arctic coast in search of food, 1002 area of the Arctic National Wildlife Refuge, Alask...

Steve Knell / Rock ptarmigan (Lagopus mutus) male part way through changing into summer plumage, in light snow shower, Cairngorms National Park, Scotland, April

Orsolya Haarberg / Rhiolite mountains at Landmannalaugar. Rhyiolite volcanism. Iceland. June 2008

Sue Flood / Lone polar bear (Ursus maritimus) walking on ice in the Arctic Ocean, July

Hanne & Jens Eriksen / Coastal landscape near Uelen, Bering Strait, Siberia, Russia, summer

Staffan Widstrand / Coastline with iceberg, Antarctic Peninsula

Tui De Roy / Adelie Penguin (Pygoscelis adeliae) group crowding on melting summer ice floe, Possession Island, Ross Sea, Antarctica

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

Tui De Roy / Adelie Penguin (Pygoscelis adeliae) group crowding on melting summer ice floe, Possession Island, Ross Sea, Antarctica

Konstantin Mikhailov / Altai mountains Plateau Ukok - View to China's Five Sacred Peaks from China / Russia border

Konstantin Mikhailov / Altai mountains view towards Kazakhstan from China / Russia border

Staffan Widstrand / Reindeer (Rangifer tarandus) male grazing, a snowy summer day, Varanger National Park, Arctic Norway

Nick Upton / Spiny broom (Calicotome villosa) with endemic Mouse ear chickweed (Cerastium supramontanum) amongst it. Branched asphodel (Asphodelus ramosus) in background with mountains beyond. Supramonte range, ne...

Nick Upton / Mouse ear chickweed (Cerastium supramontanum) amongst Spiny broom (Calicotome villosa). Branched asphodel (Asphodelus ramosus) in background with mountains beyond. Supramonte range, near Urzulei, Sard...

David Pattyn / Group of snowshoe hikers passing snow covered mountain refuges in spring. These refuges are used in summer by herders to sleep while watching for their cattle, Gran Paradiso National Park, Aosta Valle...

Stefan Christmann / Adelie penguin (Pygoscelis adeliae) four standing on sea ice as it breaks up in summer. Atka Bay, Antarctica. February.

Guy Edwardes / Landscape of Alpe di Siusi, Dolomites, Italy, August 2018.

Guy Edwardes / Landscape of Alpe di Siusi, Dolomites, Italy. August 2018

Ashley Cooper / Old hunting lodge in the Picos de Europa mountains below Pena Vieja, with cows on their summer high pastures. Spain. June 2005

Ashley Cooper / The Aiguillette des Posettes with Bilberry plants colouring up in late summer, above Chamonix, French Alps, and the rapidly retreating Glacier du tour. France, September 2014.

Ashley Cooper / The Aiguillette des Posettes with Bilberry plants colouring up in late summer, above Chamonix, French Alps, and the rapidly retreating Glacier du tour. September 2014.

Ashley Cooper / The Dru mountain above Chamonix France. Recently a massive rockfall involving millions of tons of rock was caused by meting permafrost in the high summer temperatures. Permafrost holds many alpine pea...

Danny Green / Arctic fox (Alopex lagopus) in the snow, in summer coat, Svalbard, Norway, April

Olga Kamenskaya / Aeial view of landscape with last remnants of snow in summer, Nenets Autonomous Okrug, Arctic, Russia , July 2017

Olga Kamenskaya / Aeial view of landscape with last remnants of snow in summer, Nenets Autonomous Okrug, Arctic, Russia, July 2017

Roger Powell / Thawing lake and emerging marsh habitat from the frozen tundra landscape. Whooper Swan (Cygnus cygnus) breeding habitat. Borselvfjellet, Finnmark, Norway, June.

Erlend Haarberg / Mountain hare (Lepus timidus) portrait, moulting from winter to summer coat, Vauldalen, Norway. May.

Bruno D'Amicis / Apollo butterfly (Parnassius apollo) on mountain thistle. Abruzzo, Central Apennines, Italy, Summer.

Melvin Grey / Ptarmigan (Lagopus muta) adult male and female, Cairngorms, Scotland. June.

Melvin Grey / Rock Ptarmigan (Lagopus muta) adult male in winter plumage, beginning summer moult, standing on rocks covered in orange lichen, Churchill, Manitoba, Canada. June.

Melvin Grey / Rock Ptarmigan (Lagopus muta) adult male in winter plumage, beginning summer moult, standing on rocks covered in orange lichen, Churchill, Manitoba, Canada. June.

Connor Stefanison / Two White-tailed ptarmigan (Lagopus leucura) perched on a rock at dusk, Hope, British Columbia, Canada. July.

Michel Roggo / Lac de Fenetre, alpine lake, 2456 m above sea level, Canton of Valais, Switzerland. June 2011. Photographed for The Freshwater Project

Andy Trowbridge / Rock Ptarmigan (Lagopus muta) female in summer plumage, sitting on rock. Bernese Alps, Switzerland. August.

Erlend Haarberg / Rock ptarmigan (Lagopus muta) moulting into summer plumage at Aurlandsfjorden. Aurland, Sogn og Fjordane, Norway, June 2012.

Eric Dragesco / Wild Snow leopard (Uncia uncia) lifting and moving a kill it is feeding on, Altai Mountains, Mongolia, August.

Eric Dragesco / Wild Snow leopard (Uncia uncia) grooming itself on a mountainside, Altai Mountains, Mongolia, August.

Eric Dragesco / Wild Snow leopard (Uncia uncia) climbing among rocks on a mountainside, Altai Mountains, Mongolia, August.

Eric Dragesco / Wild Snow leopard (Uncia uncia) climbing among rocks on a mountainside, with the sun coming out, Altai Mountains, Mongolia, August.

Francois Savigny / Polar bear and cub on drifting iceberg {Ursus maritimus} summer, Svalbard, Norway

Francois Savigny / Sleeping Polar bear and cub on drifting iceberg {Ursus maritimus} summer, Svalbard, Norway

Markus Varesvuo / Ptarmigan (Lagopus mutus) camouflaged against rocks in summer plumage, Utsjoki Finland September

Markus Varesvuo / Ptarmigan (Lagopus mutus) camouflaged against rocks in summer plumage, Utsjoki Finland September

Markus Varesvuo / Ptarmigan (Lagopus mutus) flock camouflaged against rocks in summer plumage, Utsjoki Finland September

Markus Varesvuo / Ptarmigan (Lagopus mutus) camouflaged against rocks in summer plumage, Utsjoki Finland September

Markus Varesvuo / Ptarmigan (Lagopus mutus) camouflaged against rocks in summer plumage, Utsjoki Finland September

Pal Hermansen / Landscape through changing seasons - photograph by Pal Hermansen 'The passage of time' of the same woodland scene in summer, Valer, Ostfold County, Norway. January 2015.

Pal Hermansen / .hanging seasons, a summer image in winter landscape. - photograph by Pal Hermansen 'The passage of time' of the same scene in summer, Valer, Ostfold County, Norway. January 2015.

Bernard Castelein / River and ice summer landscape between Hjerkinn and Snohetta, Dovrefjell, Norway, July

Bernard Castelein / River and ice summer landscape between Hjerkinn and Snohetta, Dovrefjell, Norway, July

Bernard Castelein / River and ice summer landscape between Hjerkinn and Snohetta, Dovrefjell, Norway, July

Alex Hyde / Alpenrose (Rhododendron ferrugineum) in mountain landscape, Nordtirol, Austrian Alps June

Pal Hermansen / Willow ptarmigan (Lagopus lagopus) in snow with icebergs, Jokulsarlon, Iceland, June.

Heike Odermatt / Tundra with last snow in summer, Spitsbergen, Svalbard, Norway

Wild Wonders of Europe / Widstrand / Humpback whale (Megaptera novaeangliae) bulk feeding on Herring (Clupea harengus) in coastal waters, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on...

Wild Wonders of Europe / Widstrand / Humpback whale (Megaptera novaeangliae) bulk feeding on Herring (Clupea harengus) in coastal waters, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on...

Erlend Haarberg / Globe-flower (Trollius europaeus) flowering in front of the Svartisen ice cap and the Flatisvatnet lake, Glomdalen, Saltfjellet-Svartisen National Park, Norway, August 2015.

Sven Zacek / Polar bear (Ursus maritimus) with Glaucous gull (Larus hyperboreus) in snowfall, Svalbard, Spitsbergen, Norway, June.

Sven Zacek / Polar bear (Ursus maritimus) in snowfall, sticking out its blue tongue, Raudfjorden Fjord, Svalbard, Spitsbergen, Norway, June.

Andy Trowbridge / Temminck's stint (Calidris temminckii) in summer plumage, running across snow, Oppland, Norway, June.

Andy Trowbridge / Temminck's stints (Calidris temminckii) displaying, in summer plumage, Oppland, Norway, June.

Erlend Haarberg / Rock ptarmigan (Lagopus muta) female, Iceland, August.

Erlend Haarberg / Rock ptarmigan (Lagopus muta) female in summer plumage, Sarek National Park, Laponia World Heritage Site, Lapland, Sweden, September.

Erlend Haarberg / Rock ptarmigan (Lagopus muta) female in summer plumage, Sarek National Park, Laponia World Heritage Site, Lapland, Sweden, September.

Jussi Murtosaari / Ptarmigan (Lagopus muta) changing into summer plumage, Utsjoki, Lappi, Finland, May.

Espen Bergersen / Humpback whales (Megaptera novaeangliae) feeding on Herring (Clupea harengus) Kvaloya, Troms, Northern Norway. November.

Markus Varesvuo / Ptarmigan (Lagopus mutus) female in summer plumage, Ivalo, Finland, June

Markus Varesvuo / Ptarmigan (Lagopus mutus) in transition from winter to summer plumage, Ivalo, Finland, June

Markus Varesvuo / Ptarmigan (Lagopus mutus) in summer plumage in habitat, Ivalo, Finland, June

Mary McDonald / Rock ptarmigan (Lagopus muta) pair mating with female in summer plumage and male in winter plumage, Longyearbyen, Spitsbergen, Svalbard, Norway. June.