The current in the Atlantic Ocean that helps regulate the climate across the world has reached a 1,000-year low – and scientists warn that it could be trouble.
The current, which is called the “conveyor belt of the ocean,” swaps out warm water that comes from the equator area with the Arctic’s much colder water.
Geologist David Thornally says that the current – technically, the Atlantic Meridional Overturning Circulation, or AMOC – “plays a key role in the distribution of heat” on Earth. He says that melting ice from Greenland causes a flood of fresh water to flow through the oceans, but because fresh water isn’t as dense as salt water is, it rises to the top and floats on the ocean’s surface. One theory is that this slows the ocean’s circulation, although scientists haven’t been able to pinpoint an exact cause for the slowing.
According to the geological record, the same thing may have happened during the last ice age and it’s possible that it completely stopped the current.
“Evidence from the past suggests that it actually did happen during the last ice age, and it is possible that it could happen in the future, although at the moment we consider it very unlikely,” says Thornally. “What we don’t really know is, are we close to one of those tipping points where runaway processes could suddenly allow the mark to weaken much quicker than it has been doing?”
Scientists agree that this slowdown – or worse, a complete stop – would have tremendous effects on ocean ecosystems.
“These delicate ecosystems rely on ocean currents to supply their food and disperse their offspring,” says Professor Murray Roberts of the University of Edinburgh. “Ocean currents are like highways spreading larvae throughout the ocean, and we know these ecosystems have been really sensitive to past changes in the Earth’s climate.”
The complete shutdown of the AMOC was the premise for the movie The Day After Tomorrow, but scientists don’t believe we’re facing anything that extreme.
What Do You Think?
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