Arctic Icescapes in Pictures

A broken block of sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica as it sails through the Victoria Strait while traversing the Arctic's Northwest Passage. AP Photo/David Goldman
Sea ice forms when the top layer of water reaches freezing point, usually around the start of October. As temperatures continue to fall, this first-year ice grows downward until it is several feet thick. If the ice survives the following summer melt it becomes second-year ice. Another cycle and it becomes multi-year ice, which is the toughest kind. AP Photo/David Goldman
Broken sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica as it traverses the Arctic's Northwest Passage. AP Photo/David Goldman
Sea ice emerges in the Arctic's Northwest Passage. AP Photo/David Goldman
Broken sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica as it sails through the Victoria Strait. AP Photo/David Goldman
Water sprays as a block of sea ice is broken by the hull of the Finnish icebreaker MSV Nordica. AP Photo/David Goldman
The bow of the Finnish icebreaker MSV Nordica pushes down sea ice as it sails through the Victoria Strait. AP Photo/David Goldman
Broken sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica as it sails through the Victoria Strait while traversing the Arctic's Northwest Passage. AP Photo/David Goldman
The Finnish icebreaker MSV Nordica sails through the Franklin Strait. AP Photo/David Goldman
Broken sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica. AP Photo/David Goldman
Broken sea ice is pushed aside as the Finnish icebreaker MSV Nordica sails through the Franklin Strait. AP Photo/David Goldman
A block of sea ice floats in the wake of the Finnish icebreaker MSV Nordica. AP Photo/David Goldman
Broken sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica. AP Photo/David Goldman
As temperatures continue to fall, this first-year ice grows downward until it is several feet thick. If the ice survives the following summer melt it becomes second-year ice. Another cycle and it becomes multi-year ice, which is the toughest kind. AP Photo/David Goldman
Broken sea ice emerges from under the hull of the Finnish icebreaker MSV Nordica as it sails through the Franklin Strait while traversing the Arctic's Northwest Passage. AP Photo/David Goldman