Giant underwater waves deep below the ocean’s surface-some as tall as 500 meters-play an important role in how the ocean stores heat and carbon, according to new research.
An international team of researchers calculated the effect of these waves and other forms of underwater turbulence in the Atlantic Ocean and found that their importance is not being accurately reflected in the climate models that inform governments policy.
The majority of the heat and carbon emitted by human activity is absorbed by the ocean, but how much it can absorb is dependent on turbulence in the ocean’s interior, as heat and carbon are either pushed deep into the ocean or pulled toward the surface. The importance of these underwater waves in heat and carbon transport is not fully understood.
The results of the study showed that turbulence in the interior of the oceans is more important for the transport of carbon and heat on a global scale than had been previously imagined.
Ocean circulation transports warm waters from the tropics to the North Atlantic, where they cool, sink and return southwards in the deep ocean like a conveyor belt. The Atlantic branch of this circulation system, called the Atlantic Meridional Overturning Circulation (AMOC), plays a key role in regulating global heat and carbon budgets. Ocean circulation redistributes heat to the polar regions of the Earth.
Over the past few decades, researchers have been investigating whether the AMOC may be a factor in why the Arctic has lost so much ice cover, while some Antarctic ice sheets are growing. One possible explanation for this is that heat absorbed by the ocean in the North Atlantic takes several hundred years to reach the Antarctic.
Now however, using a combination of remote sensing, ship-based measurements and data from autonomous floats, the researchers have found that heat from the North Atlantic can reach the Antarctic much faster than previously thought. Also, turbulence within the ocean-in particular large underwater waves-plays an important role in the climate.
“Climate models do account for turbulence, but mostly in how it affects ocean circulation,” said Dr. Laura Cimoli of Cambridge University. “But we’ve found that turbulence is vital in its own right, and plays a key role in how much carbon and heat gets absorbed by the ocean, and where it gets stored.”
The research suggests the need for the installation of turbulence sensors on global observational arrays and a more accurate representation of small-scale turbulence in climate models, to enable scientists to make more accurate projections of the future effects of climate change.
https://phys.org/news/2023-03-giant-underwater-affect-ocean-ability.html