Oceanographers have noticed changes in the North Atlantic that could lead to a step-function ice age.
About 12,800 years ago, North Atlantic waters cooled dramatically and so did the North Atlantic region. It took only about a decade to move into a cold spell that lasted close to 1,300 years, Gagosian says. The most recent shutdown in the North Atlantic circulation is believed to have occurred 500 years ago, wiping out established Norse settlements and vineyards that once thrived in Greenland, he says. A recent U.S. National Academy of Sciences report, entitled "Abrupt Climate Change: Inevitable Surprises," notes that climate changes have occurred with "startling speed" in the past. And next time, the report said, the cost to agriculture alone could be in the $100- to $250-billion range."
