The “Atlantic meridional overturning circulation” (AMOC) may sound complicated, and it mostly is, but it’s defined very simply as the system of Atlantic Ocean currents which carry warm water north and cold water south.
And the AMOC is slowing down by record-breaking amounts. According to new research published in Nature, the Atlantic Ocean currents have slowed down by about 15 percent since the mid-twentieth century, marking the most sluggish it’s been in the last 1,000 years. The AMOC plays an important role in regulating global climate, and perhaps unsurprisingly, climate change is making the rate of slowdown much more severe.
To put into perspective how sharp of a change that 15 percent is, the Atlantic Ocean has seen a decrease of about 3 million cubic meters of water per second, which is equal to the amount of water in 15 Amazon rivers.
There were two studies (both published in Nature) which approached the matter in different ways. For the first study, the researchers looked into ocean floor sediment, a reliable way to determine current strength because stronger currents can move larger grains of sediment farther. The second study created advanced climate models and compared it with sea temperatures over the past hundred years.
There’s some disagreement about when the problem first arose. The first study suggests that climate change was behind the phenomenon in the first place, with the AMOC first weakening around the beginning of the industrial era in 1850.
Whereas the second study suggests that this slowdown in current didn’t begin until the middle of the twentieth century, although they claim it was naturally dipping downward before climate change threw the trajectory off even further.
Regardless, all of the research appears to be drawing the same conclusions, and while the ocean currents won’t cause the severe problems that led to the plot of The Day After Tomorrow, this is another potential stepping stone to much bigger problems.
