Study: Gulf Stream is slowing down. That means higher ocean along the Eastern U.S.

Longtime Chesapeake Bay boaters have stories of the wind and tide sucking water out of the rivers, lowering depth levels by several feet in one day, and the Gulf Stream is the straw that usually does it. A new report says it’s about to get worse.

Gulf Stream map
Map of the Gulf Stream.Ireland & Newfoundland are the top of the blue & red squiggly lines. (Originally published on RealClimate.com, courtesy researcher Stefan Rahmstorf, Professor of Physics of the Oceans, Potsdam University)

The Washington Post’s Chris Mooney calls it “another potential mega-scale perturbation.” He’s talking about what’s happening between Ireland and Newfoundland and it’s likely impact the U.S. East Coast.

Let’s back up a bit: The Gulf Stream is a strong current, pulling water across the globe. It also pulls water away from our Atlantic shore (giving us nice wide beaches at times).

Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research and a group of co-authors just published a study in  Nature Climate Change saying the Gulf Stream is slowing down more than expected and that’s raising water levels along the Atlantic faster than expected. But fast for climatologists isn’t the same as you and I think of it.

What they found:

Rahmstorf and his team of researchers looked at global temperature for past 900 years. They found that the Gulf Stream started slowing down in 1975, more than in the past 1,100 years. They conclude it’s not a natural weather variation. It’s global warming.

They looked further and found 2014 was the warmest year on record (since record keeping began in 1880), yet there was a “remarkable cold bubble over the northern Atlantic.” Melting ice was causing the bubble!

Climate Change map: cooling areas
Linear temperature trend from 1900 to 2013 — The blue patch in the upper middle is cooling water between Ireland and Newfoundland that’s slowing the Gulf Stream. A new study says that could raise water levels along the eastern U.S. shore. (Map courtesy Nature Climate Change)

Here’s how the cooling is linked to global warming & higher water levels:

The slightly higher temps at the Greenland ice sheet are melting ice, sending fresh water into the Atlantic Ocean. That’s a problem because we have heavier salt water along our Atlantic shore that sinks to the bottom of the ocean and acts like a brake on the water current.

The Gulf Stream comes blowing by and sucks the lighter, fresher water away from the shore and on it’s way around the globe. If the wind slows, more fresh water blends with our salty water; and ocean life as we know it changes.

Here’s a NASA video demonstrating how the Gulf Stream cruises past the U.S. and around the world:

What’s it mean to us?

Life as we know it on the Chesapeake Bay is going to change in subtle ways. Certain kinds of fish will move on to stay with the salty water, Our oysters will become milder tasting because the water is less saline. The water level rises, making beaches smaller and waterfront homes lose their front yards. Colonial downtown Annapolis already floods regularly during extreme high tide.

All this is going to happen gradually and some of it can be blocked by clever engineering.

The problem, Rahmstorf says, is that previous scientific models underestimate the impact. He says it won’t be anything like the movie, The Day After Tomorrow, but “that the real flow may be more unstable than previously thought would be bad news for the future.”

For a more detailed explanation, read the March 23, 2015 report by Professor Rahmsdorf and the excellent explanation by Washington Post science writer Chris Mooney.

 

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