All of those explorers of a few hundred years ago were just slightly
too early.

Thanks to climate change, the fabled NW Passage between Europe and
Asia is now open during the summer months, no longer blocked by ice.

Adventurous cruisers can really plan a "great circle" route now,
circumnavigating the entire western hemisphere.

Apparently there is a major squabble between Canada and some members
of the international community regarding who will control the newly
available shipping channel.

http://news.bbc.co.uk/2/hi/americas/6995999.stm

For what it may be worth, you have to wonder whether the rumors of the
NW Passage that sent the Europeans into the Canadian arctic might not
have been founded upon tales handed down for scores of generations
from a time when a similar warming trend (one that obviously couldn't
have been created by internal combustion engines) made the passage ice
free?