Climate change could collapse a key Atlantic Ocean current. How that could affect Wisconsin - Milwaukee Journal Sentinel

Climate change could collapse an Atlantic current. How it could impact Wisconsin

Climate change could collapse a key Atlantic Ocean current. How that could affect Wisconsin
Laura Schulte

MADISON - If one of the major ocean currents responsible for creating our weather patterns were to collapse, Wisconsin wouldn't be immune from the drastic change, researchers say.

A new study estimated that an important ocean current — Atlantic Meridional Overturning Circulation or AMOC — could collapse by the middle of the century, or possibly any time from 2025 onward due to human-caused climate change.

The AMOC is a large system of ocean currents that carry warm water from the tropics into the North Atlantic, creating the weather we experience.

Greenhouse gas emissions are causing Greenland to warm and its ice sheet to melt. That melted freshwater in turn would enter the North Atlantic and disrupt the current.

More: Midwest states, often billed as climate havens, suffer summer of smoke, drought, heat

The collapse of the current could trigger rapid weather and climate changes for the U.S., Europe and elsewhere. It could bring an ice age to Europe and sea-level rise in cities like Boston and New York, according to a USA TODAY report, as well as stronger storms and hurricanes along the East Coast.

But what would that mean for Wisconsin, which for a long period of time was seen as a sort of climate-change haven?

Feng He, a senior scientist with the Center for Climatic Research within the Nelson Institute of Environmental Studies at the University of Wisconsin-Madison, said Wisconsin would see some pretty abrupt changes under a collapsed current, likely mirroring the major warming episode between 48,000 and 68,000 years ago.

That change is recorded in the rock formations within the Cave of the Mounds, about 30 minutes outside of Madison.

"We have a key recording of the effect," He said. "You can see the abrupt change from the circulation."

He said that within the layers of rock, which resemble tree rings, scientists were able to see what the climate would have been like, whether there was a drought or a heavy rainfall. Researchers found the abrupt climate changes within the layers and the isotopes within the rock.

Prior to the study at Cave of the Mounds, not much was known about how the Midwest was impacted by abrupt climate changes, but now there's a better understanding of how warming in other parts of the world, like Greenland, can have a wider impact.

"Wisconsin will be part of this whole global response to this event if it happens in the future," He said.

Of course, Wisconsin hasn't been immune to the changes already taking place due to human-created climate change.

The state is already seeing an increased number of storms during the summer, increased drought-like conditions in some areas, and creating hotter summers and colder winters.

"Climate change is real," He said.

But while the research at Cave of the Mounds seems to support the new study regarding the collapse of the Atlantic current, He is also cautious about the study's findings. While we know that a collapse of the current has likely happened before, causing large change's in Wisconsin's weather, researchers don't really know what caused the collapse.

"We really don't know what will happen in the future," He said. "If you don't know why something happened in the past, it's hard to predict what will happen in the future."

Laura Schulte can be reached at leschulte@jrn.com and on Twitter at @SchulteLaura.