Gulf Stream weakest for over 1,000 years, study finds

A group of European scientists this week presented new research claiming the Gulf Stream is weaker now than it has been at any time in the past 1,000 years. The Gulf Stream is a current in the Atlantic Ocean that plays a largely hidden role in shaping weather conditions in the United States. Much has been researched and learned about the influential stream over the past 500 years, particularly through the expertise of one of America’s Founding Fathers, Benjamin Franklin.

But over the past few decades, a change in the circulation of the Gulf Stream has become weaker than at any time in the past millennium, according to a recently published study by scientists from Ireland, Britain and Germany. The weakening of the Gulf Stream, officially known as the Atlantic Reversing Meridional Circulation (AMOC), may be primarily related to a catalyst, the researchers said: human-caused climate change.

The current of the Gulf Stream moves a massive amount of water through the Atlantic Ocean. According to Stefan Rahmstorf, one of the study’s authors, it moves nearly 20 million cubic meters of water per second, acting like a giant conveyor belt.

How strong is a current? “Almost a hundred times the flow of the Amazon,” he told the Potsdam Institute.

The main function of the Gulf Stream is to redistribute heat on Earth through the ocean current. The oceanic circulatory system plays a crucial role in many weather patterns around the world, especially along the eastern seaboard of the United States.

The story continues

Rahmstorf said his team’s research was revolutionary to be able to combine previous research elements to piece together a 1,600-year-old picture of the evolution of AMOC.

“The results of the study suggest that it was relatively stable until the end of the 19th century,” he said. “With the end of the Little Ice Age around 1850, ocean currents began to decline, followed by a second more drastic decline since the mid-20th century.

So what are the implications of this drop in ocean currents? AccuWeather’s senior meteorologist Bob Smerbeck said it could likely lead to sea level rise if water levels warmed this year. However, Smerbeck added that it was unclear how warm the waters could be.

Previously, studies have shown that rising water temperatures and rising sea levels can lead to more extreme weather events such as stronger tropical storms, a higher likelihood of extreme heat waves, or a decrease in summer precipitation.

However, other researchers have also published contrasting data, suggesting that the Gulf Stream has not really declined over the past 30 years. Using a different data modeling system, researchers in the UK and Ireland gathered data from climate models that they said in a study published earlier this month showed “no overall decline. of AMOC ”.

“Our results reinforce the fact that adequately capturing changes in the deep circulation is essential for detecting any AMOC decline linked to anthropogenic climate change,” write the authors in their study, which was written just days before Rahmstorf’s team does not publish its research on the subject.

Smerbeck, who has been a meteorologist at AccuWeather for nearly 25 years, called for caution in interpreting the new research claims.

<< A possible repercussion examined in article 1 [the first study mentioned above] about warming waters along the east coast due to a slowdown in AMOC could lead to sea level rise due to thermal expansion of seawater. It seems plausible, " Smerbeck said. But, he added that the amount of rising seawater would depend on how warm the waters could get and he wasn't ready to speculate on that.

How was the Gulf Stream as we know it today discovered? Well, the discovery was fueled by a need for increased efficiency in the postal service and was inspired by the empiricism of the whalers.

In 1768, Benjamin Franklin was working in London as a deputy postmaster, according to The Smithsonian Magazine, responsible for overseeing the arrival of mail to and from the American colonies. His cousin, Timothy Folger, worked at the same time as captain of a merchant ship.

Franklin once asked Folger why his merchant ships arrived to the colonies much faster than Franklin’s postal ships returned to England. Folger explained to his cousin that the merchant captains followed the advice of the whalers, who followed a “hot and strong current” to track down and kill the whales.

While Franklin said courier captains were too proud to take the advice of “ordinary American fishermen,” navigating against the tide was costing precious time, according to author Laura Bliss.

So Folger sketched out a general current location for Franklin, nicknamed it the “Gulph Stream”. However, Franklin’s letter carriers refused to follow instructions.

But when Franklin switched allegiance to the burgeoning United States during the War of Independence, he mapped out a more precise AMOC route and gave it to the French allies, giving them a key advantage in battle. of the European Maritimes, according to The Smithsonian. The combination of Folger’s knowledge of whaling and Franklin’s mapping would become crucial in later understanding the importance of the current, although originally they were just trying to figure out how to deliver the mail faster.

Although knowledge of AMOC dates back only a few hundred years, Smerbeck said that dating currents can be done in a number of ways. Direct measurements with oceanic instruments only date back to 2004, he said, but other methods can help piece the puzzle together, such as coral analysis and historical logbook data.

“Tree rings can tell how humid or dry the neighboring earth’s climate was in the past, which may be related to sea surface temperatures,” Smerbeck explained. “Ice cores can say pretty much the same as well as the heat or cold of the past,” he said. “Ocean sediments can indicate whether there have been periods of high or low runoff due to near-land precipitation, which could be related to warm or cold sea surface temperature in the past. The researchers used all of these clues to shed light on the understanding, which dates back over a millennium, to the Gulf Stream.

Check back regularly to AccuWeather.com and stay tuned AccuWeather Network on DirecTV, Frontier, Spectrum, Fubo and Verizon Fios.