This is a photo released by Push Pictures showing British explorer and endurance swimmer Lewis Gordon Pugh in the waters of the North Pole Sunday July 15, 2007. Pugh took to the freezing waters in just his Speedo swimming briefs, cap and goggles to highlight the devastating impact of climate change on the natural world. It took him 18 minutes and 50 seconds to swim 1 kilometre (0.6 miles) in in waters created by melted sea ice at temperatures of minus 1.8C
(AP Photo / Jason Roberts, Push Pictures)
In this Sunday, July 2, 2006 photo provided by Greenpeace via Zuma Press, American explorers, Lonnie Dupre, left, and Eric Larsen hold up a U.S. flag claiming to become the first-ever to complete a trek to the North Pole in summer. The duo undertook the expedition to bring attention to the plight of the polar bear which scientists claim could be extinct as early as 2050 due to the effects of global warming.
(AP Photo/Greenpeace, ZUMA Press, Eric Larsen)
This graphic released by the National Geographic Society Tuesday Jan. 14, 1997 is part of oceanographic study by the U.S. and Russia on the Arctic Ocean. This cross-section Arctic Ocean map, combining U.S. and Russian data, represents a transect of Arctic waters, red line, showing an area in Greenland, left, where warmer surface water is pulled in and cooled, forming a mass of deep ocean water. By releasing the information, both nations hope to help scientists around the world who are investigating environmental questions such as global warming.
(AP Photo/National Geographic Society)
In this undated photo released by Polar Challenge via the Ben Bulletin, teams of skiers in the Polar Challenge plod ahead on their way to the magnetic north pole.
(AP Photo/Polar Challenge via Bend Bulletin)
This photo provided by the Bancroft Arnesen Explore shows Ann Bancroft of Minnesota talking on a satellite phone during a North Pole expedition with Norwegian Liv Arnesen in Ward Hunt Island, Canada, Tuesday, March 6, 2007. What was intended to be a 530 mile (853 kilometers) trek across the Arctic Ocean to bring attention to global warming was called off March 10, after Arnesen suffered frostbite in three of her toes.
(AP Photo/Bancroft Arnesen Expedition, Hunter Bancroft)