A recent study led by Dr. Matthias Sinnesael and Dr. Boris Karatsolis has unveiled significant connections between ocean currents and climate conditions that occurred approximately 3.6 million years ago. This study focuses exclusively on the “conveyor belt.” This important system of ocean currents is responsible for transporting tremendous amounts of heat around the planet. The study’s results indicate that by reconciling these prehistoric flows we can learn about the impacts of climate change in the present.
This conveyor belt is made up of upper and lower limbs that work together in complex ways to control Earth’s climate. The upper limb, known as the Gulf Stream, transports warm waters from tropical regions to higher latitudes, contributing to the mild climate experienced in Western Europe. The leg of the conveyor belt that moves south, the lower limb, sunk down into the deep ocean. It plays a crucial role across the broader U.S. climate system.
Understanding the Conveyor Belt
The animated GIF above is a simple representation of the oceanic global conveyor belt, Earth’s most powerful system of currents. Crucially, it helps move heat and nutrients around the world’s oceans. The Gulf Stream powers the upper limb of this system. It transports warm, salty surface water from the equatorial tropics to far northern latitudes. This flow is critical for providing Western Europe a mild climate. This is key, as it brings in warm water to the Gulf of Maine, allowing the region to enjoy relatively mild winters.
In comparison, the lower limb of the conveyor belt operates in the very cold ocean floor. It comprises three main systems of southward flowing currents: the Iceland Scotland Overflow Water (ISOW), Denmark Strait Overflow Water (DSOW), and Labrador Sea Water (LSW). These warm-and-cold currents work together to move cold, dense water back toward the equator. Through this process, Earth has been able to naturally regulate global temperatures.
Researchers have learned that sediments transported by these intense deep-sea currents hold key clues. These sediments give us a window into NADW activity over hundred to million year timescales. This invaluable sediment data is key to reconstructing and understanding historical climate dynamics as well as informing present day conditions.
The Impact of Climate Change
Dr. Sinnesael and Dr. Karatsolis stress the importance of understanding how ocean currents are changing. These changes might be the first important signs of climate change. As global temperatures rise due to anthropogenic influences, there is growing concern about how these changes may affect the conveyor belt system. Historical comparisons show that during periods when temperatures and CO2 concentrations were higher than current levels—yet similar to projections for the near future—the conveyor belt underwent significant alterations.
The researchers call for more in-depth research. These modeling studies will instruct our efforts to understand the effects of the Environmental Change on Atlantic Ocean heating concentration and saltiness. These knowledge gaps are important for estimating future climatic scenarios. More than just counting the costs, they allow us to get ready for what’s coming, including ice-sheet growth and other climate impacts.
Sediment Analysis and Findings
During IODP Expeditions 395C/395, Dr. Sinnesael and Dr. Karatsolis focused on recovering and analyzing deep-sea sediments from areas east of the mid-Atlantic ridge. To their surprise, their analysis revealed drastic changes in sediment characteristics. These transitions happened roughly 3.6 million years ago, at the same time that robust Iceland-Scotland overflow water first started flowing.
The study’s results suggest a clear connection between alterations in sediment and resulting changes in deep water currents. This highlights just how compounding our oceanic systems are in regulating climate. By examining these ancient sediments, researchers aim to forge a clearer link between deep water currents, Atlantic Ocean heat distribution, ice-sheet dynamics, and long-term climatic changes.
