A massive current system that runs deep through the vast Atlantic Ocean has an impact on temperatures, climate, sea levels and weather systems around the world. Any disruption of its flow could have rapid and catastrophic consequences for the global climate. And a new study has some gloomy predictions about the future of the Atlantic Meridional Overturning Circulation, as it is known, and whether it could stop altogether in the coming decades.
This comes from a new study published Thursday in the journal Nature Geoscience, which reconstructs the history of the circulating current since about 400 AD. Researchers believe that the circulation is now the weakest it has ever been in the range.
But understanding what that means – and whether the circulation will stop – requires some background on how it all works.
The Atlantic meridional reversal – or “AMOC” for short – can be compared to a series of conveyor belts. The direction of the belts and their “contents” differ: one belt containing hot water flows north, cools and evaporates, increasing the salt content in that region of the ocean. As the water gets colder and heavier, it sinks and flows south, creating a second southerly movement. These belts are interconnected by regions in the Labrador Sea, the Nordic Sea and the Southern Ocean. They are responsible for bringing mild, warm weather to Europe and keeping the sea level on the east coast of the United States.
According to the authors of the Nature Geoscience study, AMOC is weakening. The culprit is probably the global climate crisis. As North Pole ice and Greenland ice melt, while rain and snow levels rise, the water flowing north becomes less salty and dense. This in turn slows down the extent to which it flows southward and weakens AMOC as a whole.
The authors of the article estimate that AMOC would weaken by about 34% to 45% by the end of this century. If that happened then we would expect huge winter storms, heat waves and droughts in Europe. In the United States, sea levels could rise to dangerous levels, threatening major coastal cities such as New York, Boston and Miami, creating millions of climate refugees in the process.
Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, who co-authored the study, told The Guardian that ‘we run the chance to cause [a tipping point] in this century, and the circulation would decrease within the next century. We’re extremely unlikely to have activated it yet, but if we do not stop global warming, it’s increasingly likely that we’ll activate it. ‘
These are not the only important and apocalyptic consequences that will occur if climate change is not controlled. There will be more veld fires in the West Coast states and more extreme weather conditions such as massive hurricanes, thunderstorms and winter storms. Large parts of the planet will be too hot and dry to live in, and it will be harder to produce enough food to sustain the human population. As people are forced to live closer to each other, there is likely to be greater conflict, especially as the scarcity of resources increases.