For hundreds of years following the discovery of America, European explorers searched for the North-West Passage, a hypothetical shortcut to Asia and the Indies which would save them the arduous trip around Africa or South America. They eventually found it (Roald Amundsen navigated it in 1903, before moving on to the South Pole), but it was blocked by ice year round and impassable to commercial shipping. However, global warming has changed that - the North-West Passage is now nearly ice-free and open for navigation for the first time in recorded history.
I'm sure the cranks will continue to claim that its nothing to do with us, though.
