Why does Earth have a stubborn cold spot that is cooling?

The earth heats up relentlessly. Therefore, it is strange that there is a persistent “cold drop” in the middle of the Atlantic Ocean.

The cold drop (also known as a “warming hole”) is like a dazzling pimple, easily evident on recent NASA surface temperature maps. Overall, the ocean’s surface has heated to nearly 2 degrees Fahrenheit (1 degree Celsius) since 1900 as the seas continuously absorb colossal amounts of human-made heat. However, the temperatures of the sea surface in the warming hole of the North Atlantic, located below Greenland, I have cooled up to 1.6 degrees F (or 0.9 C) during this period, which then cools the air above this coldest patch of the ocean.

Research, published Monday in the journal Climate change, provides further evidence of how changes in ocean warming have sustained this impressively unconditional cold bubble. It is an unusual phenomenon, but as humanity adds more heat to Earth’s climate system, year after year, there will inevitably be consequences, some more obvious or expected, and some strange.

“Anthropogenic climate change changes the circuitry of the climate system,” said Kristopher Karnauskas, an oceanographer at the University of Colorado Boulder who was not involved in the research. “[The cold blob] it is an interesting manifestation of the danger we are causing. “

(There is increasing evidence of a dangerous future, including a mega-city in the United States, the rapid disappearance of sea ice, extreme storms, relentless global warming, increasing wildfires, and beyond.)

Persistent gout has been particularly prominent since 2015, spanning the five warmest years on record in the world. “The North Atlantic is marching to the beat of its own drummer,” said Josh Willis, a NASA oceanographer who also had no role in the study. And a key conclusion from this new research, Willis emphasized, is that there may be a number of mechanisms that drive the single heating hole.

Are here:

1. Change of ocean currents

There is growing evidence, which this study further supports, that a major ocean current called “Southern Atlantic Tipping Circulation (AMOC), which acts as a conveyor belt while transporting warm tropical water into the North Atlantic Ocean, is slowing down Scientists suspect that the slowdown is driven by “off the charts” melting of the Greenland ice sheet, which has resulted in fresh water being poured into the North Atlantic Ocean.

The influx of water can have a momentous effect. It reduces the salinity of the ocean, which makes the water less dense. This throws a key in the ocean circulation: now, less cold water in the North Atlantic sinks naturally, preventing the flow of new tropical heaters from flowing into this ocean region (because the colder, now more floating, waters are not cleared) out of the way). Ultimately, this means there is less heat traveling into the North Atlantic, which helps keep the bubble cool, said Paul Keil, lead author of the research and a doctoral candidate at the Max Planck Institute for Meteorology in Germany.

Oceanographers expect AMOC to decline as fresh water, recently melted in a rapidly warming Arctic, is poured into the North Atlantic. The persistent cold drop provides compelling evidence that this is already happening. “AMOC is expected to slow down in response to increased greenhouse gases in the atmosphere,” said Daniel Whitt, an oceanographer at the National Center for Atmospheric Research, who was also not involved in the study.

Additionally, Keil and his team discovered that a circulation of water traveling in a circuit around the North Atlantic, called the “subpolar gyre,” has been sending heat. outside from this region The turn, which runs counterclockwise, transports relatively warmer waters further north, into the Arctic Ocean. It’s a deeply complicated system, Keil said, noting that his team is preparing a completely different study focused only on what drives this turnaround (the research is led by Rohit Ghosh, who is also studying ocean trends at the Max Planck Institute of Meteorology ).

The important point is that this turn acts to transport warmer waters out of the North Atlantic, further cooling the cold bubble.

“Then less heat will come in and more heat will come out,” Keil explained.

2. clouds

The researchers also showed that clouds played a role, albeit a smaller one, in maintaining the cold bubble.

They found that the colder ocean surface produces more low-level clouds, a type of cloud that is thick and “reflects more sunlight and therefore further cools the surface,” Keil said. This means that the heating hole is “getting stronger” in a feedback loop, Keil explained, as more cooling creates more reflective clouds, which in turn creates more cooling.

However, the role of clouds in the North Atlantic is a new and emerging finding that will no doubt require continued observation, Willis of NASA said.

It is important to note that conditions in the North Atlantic vary greatly from year to year and over decades. To discover the role of a rapidly warming climate in maintaining the cold bubble, Keil and his team used advanced computer simulations (the Grand Ensemble of the Max Planck Institute for Meteorology).

This is done by simulating the past, known as “hindcasts,” where researchers can create artificial worlds without the influence of global warming. This allows climate scientists to observe how climate change influenced a place, such as the North Atlantic, comparing our reality to worlds unaffected by human-caused global warming.

The North Atlantic is undoubtedly a complex region, with a deep ocean, abundant amounts of melting ice, massive ocean circulation and beyond. It is a place that requires more research. But today, a sustained cold drop is certainly a big part of the picture.

“It is a characteristic of the evolving ocean and the evolving climate,” said Whitt of the National Center for Atmospheric Research.