A sweeping ocean conveyor system that ushers warm tropical waters into the North Atlantic appears to have partly recovered from a near-collapse around the time that the Beatles were breaking up, but the system remains weaker than it had been since before humans figured out how to write modern music on a page.
Powerful Atlantic Ocean currents fuel Gulf streams, affect sea levels, warm cities in continental Europe and North America, and bring nutrients up from ocean depths that help sustain marine ecosystems and fisheries.
But an avalanche of cold water from the melting Greenland ice sheet appears to be slowing the ocean circulation to levels not experienced in more than 1,000 years.
That’s the conclusion of a bold new attempt to combine temperature measurements and climate-related data scrounged from coral samples, ice cores and tree rings to track the worrying decline of the critical Atlantic Ocean phenomenon. The new …