Scientists warn ocean current collapse could chill Chicago winters

Researchers indicate that a major shift in Atlantic ocean currents could lower Chicago winter temperatures by up to 10 degrees. This change could last for approximately 1,000 years. The potential cooling effect is linked to the weakening of the Atlantic Meridional Overturning Circulation, or AMOC. If this current collapses, historical data suggests Chicago winters would become as cold as those in Minnesota.

Aidan Burdick, a doctoral student at Northwestern University, studies fossilized flies to understand these past climate shifts. His work helps reconstruct the climate from 12,000 years ago when the AMOC was weak. During that period, spruce trees thrived in the region, indicating much cooler conditions. Burdick noted that air temperature is the primary factor determining where these species lived.

Current measurements suggest the risk of a full AMOC collapse has increased. Dr. Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research stated he previously viewed the risk as a few percent. He has since revised that estimate to 50 percent. Rahmstorf explained that the impacts would be massive and difficult to adapt to. He projected that temperatures in northwest Europe and parts of North Africa would drop significantly, particularly in winter. Sea levels on the U.S. East Coast could rise by a foot and a half, increasing coastal flooding.

Dr. Erin Pettit, a professor at Oregon State University, led a six-week expedition to Greenland this summer. Her team used underwater robots to attach microphones to glacier faces. The sound of melting ice provided data on melt rates. Pettit said the team was underestimating how fast ice is melting. This new data will help scientists calculate the likelihood of an AMOC shutdown.

Rahmstorf and 43 other climate scientists sent an open letter to Nordic leaders. They argued that the risk has been underestimated in previous research. The letter urged leaders to prepare for and prevent the event, which Rahmstorf called a catastrophe. He stated that the only way to reduce the risk is to move away from fossil fuels as quickly as possible. Fossil fuels currently account for at least 65 percent of global energy consumption.

The latest international climate change report expresses moderate confidence that the current will not abruptly collapse this century. However, Rahmstorf noted that even a partial weakening would cause major global impacts. He emphasized that the models show the current may already be less than half as strong as it used to be. Observations from the Greenland expedition are expected to be incorporated into climate models in the coming years. This data will help refine predictions on the probability of a shutdown.