A Current You’ve (Probably) Never Heard Of Could Change Wisconsin’s Climate Forever

Here’s what you need to know. 

A system of essential currents in the Atlantic Ocean could collapse in as little as two years. According to a new study published in Nature, the Atlantic Meridional Overturning Circulation (AMOC) is expected to collapse by 2050 or as early as 2025. 

Tl;dr Wisconsin’s climate as we know it could change forever.

This is nothing new; scientists have warned about the signs of the current’s deterioration for years. But they didn’t think it would happen this quickly. Here’s what you need to know.

What is the Atlantic Meridional Overturning Current?

The AMOC is a part of the ocean’s global “conveyer belt” of currents that transports water and nutrients across the world. This particular current within the ocean’s network circulates water from the North to the South and back within the Atlantic Ocean. Essentially, the current brings warm surface water to the poles, where it cools and turns into sea ice. 

How does that work?

What keeps the current running are differences in temperature and salt content, or the water’s density. 

“As warm water flows northwards, it cools and some evaporation occurs, which increases the amount of salt. Low temperature and a high salt content make the water denser, and this dense water sinks deep into the ocean,” Metoffice, a meteorological service company, explains. From there, this cold, dense water moves south before it warms and rises to the surface again. 

Why is it important?

The AMOC plays a crucial role in the Earth’s climate by distributing warmth, carbon, and nutrients across the Atlantic, which does a lot more than it sounds like. It impacts sea levels, trade winds, storm tracks, and weather patterns, like the annual monsoon season.

The current is a major temperature and weather stabilizer, especially for the North Atlantic Region. It’s a large reason why Europe’s winters are so mild compared to ours.

What’s causing the current to change? 

Experts say the current has been slowing down since the mid-twentieth century, and climate change is likely the biggest reason why (CITE). 

But now, with ice caps like the Greenland Ice Sheet melting at alarming rates (CITE), the current is slowing down faster than ever before. 

What does this mean for you?

As the current slows and moves closer to a complete collapse, climate patterns around the world are expected to change dramatically. 

For the US, the primary concern is rising sea levels, which will mostly impact states on the east coast. 

“This current keeps the water around New York and Boston cool, which slows the rise of sea levels in those cities because cold water takes up less space than warm water,” said the NRDC.  “If the current slows, that could change.”

Hurricanes could also become stronger and more active. 

But Wisconsin and the rest of the Midwest will not be immune to these changes. The new Nature study also found that the intensity and frequency of extreme cold will increase significantly in cities like Milwaukee. This means an AMOC shutdown could trigger harsher, colder, longer winters, as well as dramatically less rain and snowfall in places like Wisconsin. 

What can we do?

As with any kind of climate-centric problem, small changes add up and there are things we can all do to make a dent in the overall warming of our planet. 

Here are 9 places to start.