The Gulf Stream current, which serves as an important regulator of weather and climate along the Atlantic Ocean, is now the weakest it has been in at least 1,600 years. This dramatic slowing of the current, known as the Atlantic Meridional Overturning Circulation (Amoc), could usher in extreme shifts in weather patterns, such as more brutal European winters, rapid sea level rise on the American East Coast, and the disruption of essential tropical rainstorms. Suddenly, the 2004 climate-change disaster film The Day After Tomorrow, which depicted the dramatized consequences of a Gulf Stream slowdown, seems less science fiction, more predictive of a future plagued by catastrophic climate change.
Although scientists have been aware of Amoc’s slowdown since 2004, two recent studies paint a more complete picture of just how dramatic this weakening has been. “The [current] climate models don’t predict [an Amoc shutdown] is going to happen in the future,” Dr. David Thornalley, leader of one of these recent studies published in the journal Nature, told the Guardian. “The problem is how certain are we it is not going to happen? It is one of these tipping points that is relatively low probability, but high impact.” Thornalley’s team gathered and analyzed sediments from North Carolina‘s Cape Hatteras, as well as shells of marine animals at various Atlantic sites, to determine the full impact of the current slowdown. The study concludes that climate change has played at least a significant role in the weakened Amoc.
Also published in Nature, the second study used thermometer data from the past 120 years to reach a similar conclusion: Amoc is about 15 percent weaker than it was in 400 AD. While the second study places much of the blame on climate change, the first study also cites natural climate variability as a contributing factor to Amoc’s slowdown. Regardless of its causes, the weakening is recognized in both studies as a potentially destabilizing phenomenon. “If we do not rapidly stop global warming, we must expect a further long-term slowdown of the Atlantic overturning,” second study co-author Alexander Robinson told the Guardian. “We are only beginning to understand the consequences of this unprecedented process – but they might be disruptive.”
Via The Guardian