Climate change isn’t just a buzzword we hear anymore. Over the past five years or so, it transformed from a potential problem to an imminent one. We don’t currently know how to predict the changes that it will bring, but we have some ideas of what to watch for. Some of those warning signs are violent weather patterns and melting sea ice. We’ve started to see both of those things occur. Recently, a study published in Nature found that the sea ice isn’t the only thing contributing to the changing weather.
Several large currents move through our oceans. Temperature differences and salinity drive these deep-ocean currents. Colder, saltier water sinks down to the bottom of the oceans in the poles and gets pushed toward the equator. As it warms, it rises to the surface, and the surrounding water becomes less salty. Known as the Global Conveyer Belt, this deep water circulation is important.
AMOC
A study released in 2015 found that part of that belt is starting to slow down. Scientists focused on a section in the Atlantic Ocean on the part of the current called the Atlantic Meridional Overturning Circulation (AMOC.) This particular section moves water from the tropics to the North Atlantic. This current fluctuates on its own, gaining and losing strength as it flows. These fluctuations are part of the regular cycle and not a cause for concern.
The study, however, found that the current isn’t just fluctuating naturally. It’s weaker, possibly from an influx of melting sea ice in the Arctic region. The data appears to show that the current is at its weakest point in the past 1,100 years, which is a pretty significant record to hit.
Now, this sounds a bit like the theory that started off in a “Day After Tomorrow” and ended with most of the temperate regions covered in glaciers in an apocalyptic disaster. So far, no one thinks that’s going to happen, so don’t worry about the end of the world yet. However, this slowdown is happening much faster than anyone anticipated, and there’s very little we can do about it. Right now, we’re along for the ride.
What the Slowdown Means
The deep ocean currents have a significant impact on our weather systems. They do a few things, including storing heat and evaporating water. Warm water stores heat and evaporates more freely, so the hotter the oceans get, the more water escapes into the atmosphere and the more warmth the sea holds onto. This, in turn, creates conditions that lead to more severe storms, exacerbate coastal flooding and contribute to climate change.
Moisture creates the severe weather that is a harbinger of climate change. Storms occur when a cold front meets a warm front. Usually, the cold front has dry air, and the warm front has moist air. The more moisture that’s in the air, the more potential there is for a severe storm.
As climate change progresses, we see uneven warming. The poles are warming significantly faster than the rest of the planet, which is leading to a greater influx of melting sea ice. As sea ice melts, it can reabsorb the salt in the water, which decreases the salinity around the poles. The less ice there is the more exposed landmass that’s available and the warmer the land becomes, creating a feedback loop.
This has resulted in ice melting faster in some areas of the Arctic and Antarctic than others. In 2017, the Larsen C ice shelf broke off and created one of the most massive icebergs on record, contributing to fears about the speed of change around the poles. The slowdown of the AMOC could contribute further to that feedback and increase the rate of warming at the poles.
A Part of a System
The ultimate takeaway here is that we don’t know exactly what to expect from changes in the AMOC. It’s one part of a massive system so the effects might be entirely unexpected. As with many other aspects of climate change, this one part of the ocean has the potential to impact the entire world.
We need to watch it and do what we can to reduce our impact on climate change. Everything else is up to the natural processes that govern our planet.