The second largest ocean in the world, Atlantic Ocean is slowing down, its water current is slowing down to be specific. Atlantic Ocean current is the exchange of warm water from the north and the cold water from the south that regulates the global climate and flux of heat which is why it is often referred as a conveyor belt of the ocean. But recent studies suggest that the Atlantic Meridional Overturning Circulation (AMOC) which is the actual term for Atlantic Ocean current, is slowing down. In fact, it is presently at its lowest in last 1,000 years. There are two approaches made by researchers that can explain the slowed down pace of the water current linking to the climate change.
According to Jon Robson, one of the study’s authors and a researcher at the University of Reading states that following the historical data available with respect to the AMOC, the last 100 years reported the lowest point when compared to the last few thousand years. This has triggered the scientists to study it further. Current stats were released by two new research papers both published in journal Nature where both take a different approach to explain how and what took place behind the slowing down of AMOC over the past 150-odd years.
The researcher pointed out towards the formation of dense water which is the product of overturning and exchange of warm and cold water. However, fresh water formed from melting ice or any other source is not too dense which creates a problem during overturning. If elongated, freshwater can possibly shut down the AMOC which has made scientists paranoid. A similar prospect was shown in the movie “The Day After Tomorrow (2004)”, however, the events and effects that will take place if the AMOC shuts down completely will not be as catastrophic as shown. Jon asserted the fact that such incident has already been a witness during the last ice age when AMOC was shut down completely. It also means that it can occur in the future too, however, scientists are still unaware of the timeline and its probability as of yet.
Two different studies conducted by separate groups of researchers are published in the journal Nature. According to the first study, researchers analyze the sediments in the ocean floor to study the strength of the current where the sediments being shifted are reliable evidence in determining the pace of the AMOC. To put things into context, weaker ocean current would move smaller grains of sediments while strong current would shift larger grains. This is similar to how strong currents on rivers move rocks and boulders. As aforementioned, freshwater flowing through the ocean reduces its capability to become dense and thus, it reduces its strength as well. The second study took a different approach where researchers used computerized climate models and studied the effects on the ocean water based on the trends of the sea temperature. The findings were astounding since, it was recorded that the AMOC has slowed down by 15% in last 100 years which means, the current has decreased the overturning overestimated 3 million cubic meters water per second of water compared to its actual volume.
Researchers are studying the ‘tipping point’ of the ever slowing down AMOC. A tipping point is a point reaching which, the ongoing process becomes faster than usual with a very feeble probability of recovering to its original state. Similarly, researchers are contemplating the tipping point of AMOC to determine when actually will the system reaches a point where it gets weaker quicker than usual finally leading towards catastrophic events like an ice age. Max Holmes, a climate scientist stated that slowing down AMOC has triggered a bizarre response to the global warming where some of the regions have received cold weather.
There is an ongoing dispute between the reason behind slowing down of AMOC, however, it is clear that it will impact the ocean ecosystems such as deep-sea sponge grounds and coral reefs where the latter is running towards its tipping point beyond which, there is no chance of returning. Professor Murray Roberts at the University of Edinburgh who coordinates the Atlas project told BBC News “These delicate ecosystems rely on ocean currents to supply their food and disperse their offspring”. Climate change has made the oceanic ecosystems to be more sensitive than ever before and slowing down of ocean current can be a disaster since it acts as a highway to transport food and supplies for all ocean ecosystems.
As of now, reducing the output of greenhouse gas emissions can help prevent global warming which is associated with the increasing temperature and weakening of ocean currents.