Graham Eaton / View of frozen Llynnau Mymbyr, a mountain lake, with fog partly revealing a mountain ridge, Snowdonia NP, Gwynedd, Wales, UK, December

Bryan and Cherry Alexander / Drygalski Glacier, which receded 300 metres between November 2008 and 2009, South Georgia, 2009.

David Woodfall / Aerial view of pancake ice sheet cracking and melting in Hudson Bay, Manitoba, Canada, December 2004

Bryan and Cherry Alexander / Melting iceberg showing the portion underwater that is sculpted by the sea. Polar regions. Digitally created image composite

Bryan and Cherry Alexander / Meltwater pouring off iceberg above hole. Scoresbysund Fiord, East Greenland, September 2005.

Bryan and Cherry Alexander / Icicles hanging from a ledge on an iceberg, Antarctica, October 2006.

Bryan and Cherry Alexander / Icebergs in the Weddell Sea at sunset. Antarctica, October 2006.

Eric Baccega / Melting ice at Floe Edge, Arctic Bay, Baffin Island, Nunavut, Canada, April 2009.

Eric Baccega / Melting ice under expansive clouds. Floe Edge, Arctic Bay, Baffin Island, Nunavut, Canada, April 2009.

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

Mike Potts / Mendenhall Glacier in severe retreat, with blue ice indicating where the glacier has recently calved. Juneau Alaska USA, May 2010

Bryan and Cherry Alexander / Ice floes as sea ice breaks up in summer off coast of Northwest Greenland, 1980.