What is the “cold blob” of the Atlantic that cools as the rest of the ocean warms?

As ocean temperatures rise, a significant area of ​​the North Atlantic appears to be bucking this trend.

The image leaves no doubt: At the center of a planet colored red and orange, a bluish spot in the area of ​​the ocean near Canada and Greenland reveals cooler temperatures.

This patch is known as “cold blob” and began to be observed about ten years ago.

The most accepted theory to date regarding this persistent anomaly is that it is due to a delay of a global oceanic circulation system called the Atlantic Meridional Overturning Circulation, better known by its abbreviation in English, i like c

This system transports warm water from the tropics to the North Atlantic like a conveyor belt.

Simply put, it carries warm water north and sends cold water south, below the surface.

changes in the atmosphere

However, a new study found that large-scale changes in weather patterns they may play an equally important role in the formation of the cold goo.

“The change in atmospheric circulation is significant enough to have a long-term impact on climate systems,” Laifang Li, a professor of meteorology and atmospheric sciences at Pennsylvania State University, explained in a statement and co-author of the study.

According to these researchers, the North Atlantic oscillation (NAO), maybe also contributed significantly.

The findings, the scientists conclude, indicate that the NAO may play an equally important role as the AMOC.

The NAO is an atmospheric circulation pattern with a low-pressure system near Iceland and a high-pressure system near the Azores, which affect how westerly winds blow across the ocean.

During the positive phase of the NAO, the winds over the subpolar North Atlantic intensify, Li explains, and this causes an effect similar to stirring a hot liquid with a teaspoon to cool it down.

“If we want to cool a hot cup of coffee, we stir the surface and that promotes heat loss. That’s exactly what stronger winds are going to do to the ocean surface: it has a direct cooling effect.”

And, the researchers confirmed, the positive phase of the NAO has become most dominant in the last century.

This helps explain why the cold blob is not evidence against global warming, but only one counterintuitive local manifestation of climate change.

Climate impact of the phenomenon

Some studies indicate that the cold blob plays a role in slowing the melting of glaciers in this part of the world, but Li isn’t convinced there’s a direct relationship.

“We’re not sure how the presence of the cold blob might affect Arctic sea ice because the coupling between the atmosphere, the ocean, and the cryosphere (the areas on Earth where water is in a solid state, including the sea ) ice, lakes, rivers, glaciers, ice caps and frozen ground), is a multifaceted problem these are processes that compete with each other,” the researcher explains to BBC Mundo.

On the other hand, he also doesn’t think it could help lower Earth’s temperature, since the cold blob only covers part of the ocean’s surface.

“When averaged across the planet, the contribution of local temperature to the overall average may not be significant enough to offset the effects of warming elsewhere,” he says.

However, because it is a phenomenon that is also affected by climate change (due to the way it affects the various systems that make up the blob), and also because of its location, the researchers believe it is important follow its evolution.

“It is located in the deep-water formation area that is critical to the the AMOCan important heat transfer mechanism that habitable climate in the middle latitudes of the North Atlantic,” says Li.