The increasing amounts of greenhouse gases have trapped heat that causes the rising temperatures of the Earth's oceans. The global average surface temperature has increased by more than 1.6 degrees Fahrenheit or 0.9 degrees Celsius since 1906, according to National Geographic.
The rising temperature has melted glaciers and sea ice and has affected the precipitation patterns which caused the animals to change course also.
Although water temperatures have risen, one patch of water in North Atlantic seems to resist the trend, and instead of increasing in temperature, it is actually dropping.
Cold Blob in the Atlantic Ocean
This cold blob in North Atlantic has caught the attention of many climatologists ever since it was discovered in 2015. However, these experts find it challenging to explain this mysterious phenomenon due to the complexities of ocean circulation.
But a team of researchers from the Max Planck Institute for Meteorology in Germany conducted a study, published in Natural Climate Change, adding detail to this mysterious cold blob, revealing that there's more than one cause for this phenomenon.
They applied long-term climate modelling to simulate different configurations to find which match the observed plunge in temperature.
According to the researchers, one cause of this cold blob is no surprise. It actually adds to previous studies that show a current of water known as the Atlantic Meridional Overturning Circulation (AMOC) has significantly weakened beginning on the mid-20th century.
When AMOC is running at its full speed, the circulation takes warm, salty surface waters from the tropics near the Gulf of Mexico north to the European coast. This, in turn, exchanges to cold, freshwater that is supplied by the melting ice.
It is not yet clear what causes this highway of tropical water to slow down, but climate models suggest that more meltwater from Greenland added by rising global temperatures would explain this event.
Warmer temperatures on the ocean surface make it buoyant that is why it is less likely to drop as quickly, slowing the spiral. At the same time, water from the melting Arctic ice and more rainfall form a layer of salty water on the surface which could also obstruct the circulating currents.
How Does Earth's Climate Affect the Cold Blob?
The researchers used a detailed planetary climate model to identify variations in energy, carbon dioxide, and water across the ocean, land, and atmosphere in an effort to know the link between the Earth's climate and the cold blob.
Simulations based on this model helped the researchers to see what might happen if they force the AMOC to churn away at full speed, which leaves the atmosphere as the major influencing factor.
They found a small noticeable effect as the incoming warm waters cooled down and produced low-lying clouds that would reflect possible radiation which then cools the water surface even further.
The team then ran another scenario that only looked at the transport of heat of AMOC, finding that it was not just carrying energy but also dumping more of it in the circulating water of the Arctic.
But for some complicated reasons, these subpolar circulations are increasing and draws heat from the AMOC which leave the cold blob even colder.
There is more work to be done to explain the cold blob further and determining how climate change impacts it.
There is no doubt that future researchers will be paying even closer attention to the AMOC's strength in the coming years, but knowing how the cold blob operates in a world experiencing climate change help better understand what to expect in the future.
