Oceanographers Say the Atlantic's Lagging Currents Are Bad News for Global Warming
On the heels of a new, magnetic map of the world's oceans provided by the ESA, climate scientists have announced a new ocean discovery: the Atlantic Ocean's circular current, which regulates the temperatures of the US, Europe, and more, has slowed to its lowest speed in 150 years, apparently due to human-driven climate change. The implications of this are potentially world-changing: changes in the current may already be causing the destruction of fish populations, changing weather patterns, and rises in sea levels.
If you're not familiar with the Atlantic meridional overturning circulation, or AMOC, it's sort of like a conveyor belt that runs along the coast of the United States and South America, bringing warm water north and cold water south in a cyclical pattern.
The warm water travels closer to the surface of the ocean on its way up, while the colder water sinks down lower on its way down due to its density.
This system helps to regulate worldwide temperatures, but a new study published in Nature claims that the AMOC has recently reached its slowest flow rate in decades due in part to Greenland's melting ice, which has been influenced by human activity that began with the Industrial Revolution in the mid-1800s.
According to Stegan Rahmstorf, one of the study's authors, the slowdown of the AMOC is "something that climate models have predicted for a long time, but we weren't sure it was really happening. I think it is happening. And I think it's bad news."
It's important to note, however, that the study is based on estimates of the AMOC's flow over the past century and a half, not actual measurements—the study uses a variety of markers (including temperature patterns in the US) to judge how the current has changed, and the accuracy of its findings are dependent on choosing the right markers to use and interpreting them correctly.
According to oceanographer Meric Srokosz: "Essentially, what view you take of the results depends on how good you believe the models used are and likewise how well the chosen proxies represent the AMOC over the time scales of interest."
Scientists aren't sure if this weakening flow is a natural occurrence or if it's been accelerated by human activity, but if it continues, it could means huge changes for the oceans—and us.