This Tuesday, November 10, 2020, a satellite image provided by NOAA shows Tropical Storm Eta at 10:40 a.m. EST in the Gulf of Mexico, Theta, right and a tropical wave to the south that turned into Tropical Storm Iota. The overheating of the world erased meteorological records in 2020 ̵
A group of scientists from Europe presented new research this week, claiming that the Gulf Stream is weaker now than it has been at any time in the last 1,000 years. The Gulf Stream is a current in the Atlantic Ocean that plays a largely hidden role in shaping US weather patterns. Much has been studied and learned over the last 500 years about the influential current, especially thanks to the expertise of one of America’s founding fathers, Benjamin Franklin.
But in recent decades, change in the circulation of the Persian Gulf has become weaker than at any other time in the last millennium, according to a recent study by scientists from Ireland, Britain and Germany. The weakening of the Persian Stream, officially known as the Atlantic Meridian Circulatory Circulation (AMOC), could mostly be attached to a catalyst, researchers say: man-made climate change.
The Gulf Stream carries a huge amount of water across the Atlantic Ocean. According to Stefan Ramstorf, one of the authors of the study, it moves nearly 20 million cubic meters of water per second, acting as a giant conveyor.
How strong is this current? “Almost a hundred times the flow of the Amazon,” he told the Potsdam Institute.
Gulfstream’s location in the 2016 Global Real-Time Ocean Forecasting System (RTOFS) model (Image by NOAA)
The main function of the Gulf Stream is to redistribute the Earth’s heat through the ocean current. The oceanic circulatory system plays a crucial role in many climate models around the world, especially along the east coast of the United States.
Ramstorf said his team’s research is groundbreaking about the ability to combine previous pieces of research to gather a 1,600-year picture of AMOC’s development.
“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 in about 1850, ocean currents began to decline, following a second, more drastic decline since the mid-20th century.”
Original Persian Gulf mapping by Timothy Folder and Benjamin Franklin from 1768 (Image through the Library of Congress)
So what are the consequences of this decline in ocean currents? AccuWeather senior meteorologist Bob Smerbeck said it could lead to rising sea levels if water levels warm this year. However, Smerbeck added that it is difficult to know how warm the water can become.
Previous studies have shown that rising water temperatures and higher sea levels can lead to more extreme weather events such as stronger tropical storms, more likely extreme heat waves or reduced summer rainfall.
However, other researchers have also come up with contrasting data, suggesting that the Gulf Stream has not actually declined in the last 30 years. Using a different data modeling system, researchers in the UK and Ireland have collected data from climate models that they say in a study published earlier this month did not show an “overall decline in AMOC”.
“Our results confirm that adequate capture of changes in deep circulation is key to detecting any decline in AMOC related to climate change,” the authors wrote in their study, written just days before the Rahmstorf team published its study on the subject. .
Smerbeck, a meteorologist at AccuWeather for nearly 25 years, called for caution in how to interpret the new research claims.
“One possible echo discussed in Article 1 [the first study mentioned above] for warming the waters on the east coast by delaying the AMOC could lead to rising sea levels due to the thermal expansion of seawater. That seems plausible, “Smerbeck said. But he added that the amount of seawater rising would depend on how warm the water could become, and he was not prepared to speculate.
This undated engraving shows the scene on July 4, 1776, when the Declaration of Independence was approved by the Continental Congress in Philadelphia, Pennsylvania. The document, drafted by Thomas Jefferson, Benjamin Franklin, John Adams, Philip Livingston and Roger Sherman, announced the separation of 13 North American British colonies from Britain. The official signing by 56 members of Congress began on August 2. (AP Photo)
How was the Gulf Stream as we know it today discovered? Well, the discovery is fueled by the need for increased postal service efficiency and is inspired by the empiricism of whalers.
In 1768, Benjamin Franklin worked in London as deputy chief of the post office, according to The Smithsonian Magazine, responsible for overseeing the arrival of mail to and from the American colonies. His cousin Timothy Folger was working as a merchant ship captain at the time.
One day Franklin asked Folger why his merchant ships arrived in the colonies much faster than Franklin’s mail ships returned to England. Folder explained to his cousin that the trade captains followed the advice of whalers, who followed a “warm, strong current” to track and kill the whales.
While Franklin says mail captains are too proud to follow the advice of “ordinary American fishermen,” sailing against the current is costly, according to author Laura Bliss.
So Folger outlined a common location for Franklin, calling it the Gulf Stream. However, Franklin’s postal carriers refused to follow the instructions.
Gulfstream diagram, published in 1786 in the Transactions of the American Philosophical Society. (Image through the Library of Congress, Geography and Maps Department)
But when Franklin switched attachments to the thriving United States during the Revolutionary War, he mapped out a more accurate AMOC route and gave it to French allies, giving them a key advantage in the battle for European sailors, according to The Smithsonian. The combination of Folger’s whaling knowledge and Franklin’s mapping will be crucial to later understanding the importance of electricity, even if at first they are simply trying to figure out how to deliver mail faster.
While knowledge of AMOC can only go back several hundred years, Smerbeck said the dating of currents can be done in a variety of ways. Direct measurements with deep-sea instruments go back to 2004, he said, but other methods could help put the puzzle together, such as coral analysis and historical log data.
“The rings on the trees can show how humid or dry the climate of the nearby land has been in the past, which may be related to sea surface temperatures,” Smerbeck explained. “Ice cores can tell the same thing, and how hot or cold it has been in the past,” he said. “Ocean sediments can indicate whether there have been periods of high or low runoff from nearby rainfall over land, which may be related to how hot or cold sea surface temperatures have been in the past.” Researchers have used all these clues to inform the understanding that spans more than a millennium, they have developed for the Persian Stream.
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