Bryan and Cherry Alexander / Inuit man pulling aside igloo door at dusk. Igloolik, Nunavut, Canada, 1993. 40 BELOW bookplate.

Bryan and Cherry Alexander / Inuit hunter entering Igloo at dusk. Northwest Greenland, 1998.

Bryan and Cherry Alexander / Qaggiq (large communal igloo for feasts) built from ice near Igloolik. Nunavut, Canada, 1999.

Tim Laman / Boy (five years) playing in snow fort / cave in garden in winter, Lexington, Massachusetts, USA. December 2005, Model released

Eric Baccega / Igloo with lights at night by moonlight, Northwest Territories, Canada March 2007

Eric Baccega / Igloo lit up at night under northern lights (Aurora borealis) Northwest Territories, Canada March 2007

Eric Baccega / Igloo under northern lights, Northwest Territories, Canada March 2007

Bryan and Cherry Alexander / At a Selkup hunter's winter camp in the forest, a Laika dog has an 'igloo' for shelter, Ratta, Krasnoselkup, Yamal, Western Siberia, Russia 2012

Bryan and Cherry Alexander / Igloo built with blocks of snow. Igloolik, Nunavut, Canada, 1990.

Bryan and Cherry Alexander / Inuit hunter at night finishing an Igloo he has built. Igloolik, Nunavut, Canada, 1990.

Bryan and Cherry Alexander / Inuk man from Igloolik sitting inside an Igloo. Nunavut, Canada, 1990. Editorial use only.

Bryan and Cherry Alexander / Inuit hunter building an Igloo for shelter. Igloolik, Nunavut, Canada, 1990.

Bryan and Cherry Alexander / Igloo-shaped church in Iqaluit, Baffin Island, Nunavut, Canada, 1987.

Bryan and Cherry Alexander / Igloos and Inukshuks built from snow as part of the celebrations for Hamlet Day in Igloolik. Nunavut, Canada, April 2008.

Bryan and Cherry Alexander / Igloos and Inukshuks built from snow as part of the celebrations for Hamlet Day in Igloolik, Nunavut, Canada, April 2008.

Bryan and Cherry Alexander / Inuit hunter putting finishing touches to igloo. Northwest Greenland, 1998.

Bryan and Cherry Alexander / Inuit hunter putting finishing touches to igloo. Northwest Greenland, 1998.

Bryan and Cherry Alexander / Warmly dressed Inuit couple sitting outside their igloo, Northwest Greenland, 1998.

Bryan and Cherry Alexander / Newly built igloo, Northwest Greenland, 1998.

Bryan and Cherry Alexander / Inuk standing on snow block building igloo. Northwest Greenland, 1986.

Bryan and Cherry Alexander / Inuit hunter lighting stove inside igloo. Northwest Greenland, 1986.

Bryan and Cherry Alexander / Fur clad Inuk building igloo for hunting shelter. Northwest Greenland, 1980.

Bryan and Cherry Alexander / Fur clad Inuk building igloo for hunting shelter. Northwest Greenland, 1980.

Bryan and Cherry Alexander / Fur clad Inuk building igloo for hunting shelter. Northwest Greenland, 1980.

Bryan and Cherry Alexander / Fur clad Inuk building igloo for hunting shelter. Northwest Greenland, 1980.

Bryan and Cherry Alexander / Fur clad Inuk building igloo for hunting shelter. Northwest Greenland, 1980.

Bryan and Cherry Alexander / Exterior view of worlds largest igloo, the Ice Hotel at Jukkasjarvi, Sweden, 1993.

Bryan and Cherry Alexander / Man building igloo, Churchill, Manitoba, Canada, 2004.

Bryan and Cherry Alexander / Qaggiq (large communal feasting igloo) built from blocks of ice near Igloolik, Nunavut, Canada, 1999.

Bryan and Cherry Alexander / Inuit girl playing with model igloo in the Headstart early learning program. Igloolik, Nunavut, Canada, 1999.

Bryan and Cherry Alexander / John MacDonald, a Scot who lives in Canada's arctic, playing the bagpipes in a large igloo. Nunavut, Canada, 1999.

Bryan and Cherry Alexander / Qaggiq (large communal feasting igloo) made from blocks of ice at Igloolik. Nunavut, Canada, 1999.

Bryan and Cherry Alexander / Inuit hunter using snow knife to finish igloo. Igloolik, Nunavut, Canada, 1993.

Steven Kazlowski / Inupiaq photographer guide sheltering behind igloo snow blind, waiting for a Polar bear to emerge from its den, Arctic coast of Alaska. April 2009

Mark Taylor / Three Maine Coon kittens, 8 weeks, in an igloo cat bed.

Matthias Breiter / Aurora borealis over igloo, Hudson Bay, northern Manitoba, Canada

Eric Baccega / Igloo lit up at night under northern lights (Aurora borealis) Northwest Territories, Canada March 2007

Doug Allan / Isaac Shooyuk, an Inuit, building igloo, Admiralty Inlet, Baffin Island, Canadian Arctic

Martha Holmes / Inuit building igloo on sea ice, Admiralty inlet, Canada, Spring, sequence

Martha Holmes / Inuit building igloo on sea ice, Admiralty inlet, Canada, Spring, sequence

Martha Holmes / Inuit building igloo on sea ice, Admiralty inlet, Canada, Spring, sequence

Martha Holmes / Inuit building igloo on sea ice, Admiralty inlet, Canada, Spring, sequence

Sue Flood / Sue Flood with local Inuit guide, Simeonie, inside an ice igloo in Belcher Islands near Sanikiluaq, Hudson Bay on location for BBC Planet Earth Iceworlds programme. 2006

Staffan Widstrand / Traditional snow igloos, still used by tribal Inuit people, Baffin Island, Canada

Jane Burton / Domestic Cat {Felis catus} Two kittens in igloo bed

Jane Burton / Domestic Cat {Felis catus} Five 8-week kittens in igloo bed.

Jane Burton / Domestic Cat {Felis catus} Red-and-white kitten coming out of igloo cat litter tray

Jane Burton / Domestic Cat {Felis catus} Two kittens in igloo bed

Jane Burton / Domestic Cat {Felis catus} Four 8-week kittens playing in igloo bed.

Jane Burton / Domestic Cat {Felis catus} Longhaired white in igloo bed 'Annie'

Doug Allan / Man building an igloo, Baffin Island, Canadian Arctic Islands. Sequence

Doug Allan / Inuit beside igloo Admiralty inlet, Baffin Is, Canada Isaac Shooyuk. Sequence

Doug Allan / Inuit building igloo Admiralty inlet, Baffin Is, Canada Isaac Shooyuk. Sequence

Doug Allan / Inuit building igloo Admiralty inlet, Baffin Is, Canada Isaac Shooyuk. Sequence

Doug Allan / Inuit building igloo Admiralty inlet, Baffin Is, Canada Isaac Shooyuk. Sequence

Doug Allan / Inuit building igloo Admiralty inlet, Baffin Is, Canada Isaac Shooyuk. Sequence

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, Admiralty inlet, Canada, Spring, sequence

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Martha Holmes / Inuit building igloo on sea ice, sequence. Admiralty inlet Canada

Doug Allan / Cameraman Doug Allan in front of igloo. Taken during filming for Blue Planet. 1999

Doug Allan / Man building igloo on Baffin island, Admiralty Inlet, Canadian Arctic Sequence (Isaac Shooyuk)

Doug Allan / Man making igloo, Admiralty Inlet, Canadian Arctic Sequence (Isaac Shooyuk)

Doug Allan / Man building igloo on Baffin island, Admiralty Inlet, Canadian Arctic Sequence (Isaac Shooyuk)

Doug Allan / Man making igloo, Admiralty Inlet, Canadian Arctic Sequence (Isaac Shooyuk)

Igor Shpilenok / Igor Shpilenok photographing from snow hide igloo, Kamchatka, Far East Russia, photograph by Sergey Gorshkov, January 2007

Flip Nicklin / Portrait, Flip Nicklin

Flip Nicklin / Photographer portrait of Flip Nicklin with camera inside igloo

Jim Brandenburg / Igloo, Ellesmere Island, Nunavut, Canada