In 2011, Bob Pickart was aboard a research vessel in the Denmark Strait, facing a scientific mystery.
He and a team of Icelandic scientists were studying the water that flows between Greenland and Iceland. But something unexpected appeared in the data: a current that no one knew existed and that flowed in the opposite direction.
“I thought, ‘What is this?’” recalls Pickart, a physical oceanographer and scientist at the Woods Hole Oceanographic Institution in Massachusetts, United States.
Pickart returned to his main research, but the mysterious current remained a question mark in her mind for more than a decade… Until he came back for her.
Last summer, Pickart and an interdisciplinary group of researchers pursued the stream, now known as Iceland Faroe Slope Jet (IFSJ). Over six weeks and a severe storm, we go into the Arctic following the zigzag path of the current through the Nordic seas.
Finding the starting point of the current is crucial, because scientists know where it ends. The IFSJ (a deep stream of dense water) starts somewhere in the Nordic seas and flows south and east, eventually rushing through the Faroe Bank Channel, a gap in the underwater ridge running from Greenland to Scotland. From there, the waters feed the lower branch of the Atlantic meridional circulation.
The Atlantic Meridional Overturning Circulation (AMOC), often described as an ocean conveyor belt, is a complex system of currents that distributes heat and influences regional weather patterns.
But Climate models show the possibility of the AMOC slowing down or even collapsing as the planet warms. In these simulations, the intrusion of too much warm, fresh water disrupts the process that drives circulation. The consequences would be catastrophic: temperatures would plummet in northern Europe, sea levels would rise even further in the United States and Southern Hemisphere monsoons could change trajectory.
But there is an important debate in the scientific community about the time frame in which this could happen. Although the latest IPCC report states that a decline is likely after 2100, some scientists argue that collapse possible within a few decades. Others believe that although data shows waters are warming, flow in critical sections of the AMOC has remained stable.
According to Dipanjan Dey, associate professor at the Indian Institute of Technology Bhubaneswar, and other experts, the lack of consensus on modeled projections is due to the lack of long-term observations. System-wide AMOC measurements only go back 20 years.
“We don’t have the confidence to say when the tipping point will be… But while we may not see the full extent of it, we should be very prepared for it,” said Dey, who was not involved in Pickart’s research; He studies the potential impact of AMOC on monsoons.
That’s why Pickart, at 65 years old, clung to the railings to cross a hallway while strong winds and waves rocked the Neil Armstrong ship from side to side. Wait that Understanding the origin of the IFSJ and its connection to the AMOC helps fill data gaps.
“We have to understand how the system works before we can really understand how it is going to change as the climate starts to warm,” he says.
