A strange “ cold globe ” in the middle of the Atlantic Ocean that is cooling as the rest of the world warms up is caused by changing ocean currents and low-level clouds, according to a study.
- The so-called ‘warming hole’ in the North Atlantic was first seen in 2015
- Previous research connected the hole to a weakening of ocean currents on a large scale.
- German expert models, however, have revealed that other factors are at stake.
A strange “ cold globe ” in the Atlantic Ocean that is cooling as the rest of the world warms up is caused by changing ocean currents and low-level clouds, according to a study.
The drop, or ‘warming hole’, was first detected in 2015 and has been linked to a weakening of the so-called Southern Atlantic Tipping Circulation (AMOC).
However, analysis by researchers from Germany has revealed that the causes of the cooling bubble are a bit more complicated, with many different factors at play.
A strange “ cold globe ” in the Atlantic Ocean (pictured in light blue) that is cooling as the rest of the world warms up is caused by changing ocean currents and low-level clouds, he found. A study
The AMOC sees warm and salty waters transported north in the upper layers of the ocean, while colder waters near the sink drain southward in depth.
As AMOC transports heat from the tropics to the North Atlantic, it also has a vital role to play in affecting climate and climate throughout Europe.
However, the melting of the Greenland ice sheet and increased rainfall in the region prevent the colder water from sinking, weakening all circulation.
In their study, climate scientist Paul Keil of the Max Planck Institute for Meteorology in Hamburg and his colleagues created long-term climate models to determine exactly what factors are contributing to the formation of the heating hole.
The team found that the relationship between the hole and the AMOC largely depends on the effect of greenhouse gases on the atmosphere.
Furthermore, modeling suggested that heat transport outside the well is aided not only by the weakened AMOC but also by oceanic circulation at high latitude, or a “twist,” and a dump of water north of the cold bubble.
Analysis by researchers from Germany has revealed that the causes of the cooling bubble are slightly more complicated, with many different factors at play, including the weakening of the southern Atlantic tipping circulation (shown in red), a subpolar spin (blue) and a reflex increase in incoming solar radiation (yellow) through low cloud formation
Simulations that considered only the impact of the atmosphere, by modeling AMOC without the weakening seen in real life, revealed that the formation of low clouds as the incoming warm waters cool also play a role in the hole.
These clouds serve to reflect more incoming radiation from the Sun, helping to cool the Earth’s surface even further in the heating hole.
The full study findings were published in the journal Nature Climate Change.
THE CIRCULATION OF THE ATLANTIC OCEAN HAS A KEY ROLE IN THE REGULATION OF THE GLOBAL CLIMATE
When it comes to regulating global climate, the circulation of the Atlantic Ocean plays a key role.
This is due to a constantly moving deep-water circulation system, often called the Global Oceanic Conveyor Belt, which sends warm, salty water from the Gulf Stream to the North Atlantic, where it releases heat into the atmosphere and warms Western Europe.
The colder water then sinks to great depths and travels to Antarctica and eventually circulates back to the Gulf Stream.
When it comes to regulating global climate, the circulation of the Atlantic Ocean plays a key role.
This movement is fed by thermohaline currents, a combination of temperature and salt.
Water takes 1,000 years to complete a continuous journey around the world.
The researchers believe that when the North Atlantic began to warm up near the end of the Little Ice Age, fresh water disrupted the system, called the Southern Atlantic Dump Circulation (AMOC).
The Arctic sea ice, and the ice sheets and glaciers surrounding the Arctic began to melt, forming a huge natural tap of fresh water that gushed out in the North Atlantic.
This large influx of fresh water diluted the surface seawater, making it lighter and less able to sink deeply, slowing down the AMOC system.
The researchers found that AMOC has weakened more rapidly since 1950 in response to recent global warming.
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