“The Day After Tomorrow” imagines a world where a critical ocean current suddenly collapses. New research suggests that has changed rapidly in the past.
Climate change has weakened ocean currents by 10% in the past 20 years, according to a new study
The Atlantic Meridional Circulation (AMOC) is a large and delicate ocean current system that is responsible for our warm climate.
Add new research to the growing body of research sounding the alarm about impending climate disaster.
Scientists have been closely observing the Atlantic Meridional Overturning Circulation (AMOC) for years. In April, two studies found that critical currents are at risk of weakening or collapsing due to climate change, potentially affecting climate and weather conditions for hundreds of millions of people.
Even if you missed these studies, you might know about ocean currents from the movie The Day After Tomorrow. The film takes a lot of liberties with what happens when ocean currents suddenly collapse due to climate change.
Now, a new study published on April 29 shows that the AMOC changed rapidly in the past due to “violent volcanic eruptions” that ultimately cooled the entire planet.
The current threat to AMOC is not volcanoes, but excess carbon dioxide in the atmosphere due to human-induced climate change. Texas A&M’s Lucien Nana Yobo, lead author of the new study, said his study “demonstrates how sensitive the AMOC is to climate change.”
What is AMOC?
“The Atlantic meridional overturning circulation is in fact one of the key circulation systems of our planet,” said Niklas Boers of Germany’s Potsdam Institute for Climate Impact Research, author of a previous study on the subject.
AMOC is an important conveyor belt that transports seawater and air and influences the weather. Warm, salty water moves north from the tropics along the Gulf Stream off the east coast of the United States, reaches the North Atlantic Ocean, where it cools, sinks, and heads south.
The faster it moves, the more water moves from the warm surface to the colder depths.
This circulation keeps northern Europe several degrees warmer than normal and brings cooler water to the coasts of North America.
What happened then?
About 12,900 to 11,700 years ago, a violent volcanic eruption that disturbed the AMOC caused the Earth to rapidly cool, says a new study published in the peer-reviewed journal Science Advances.
Initially, scientists thought that an extraterrestrial impact, such as an asteroid or comet impact, caused the AMOC’s disruption, which scientists called the “Younger Dryas” period.
Now, research is strengthening another theory that blames the cooling on a series of violent volcanic eruptions. The cooling is caused by atmospheric changes caused by volcanoes, disrupting the AMOC (the large-scale ocean circulation “conveyor belt” that transports heat around the world), which is now at risk of weakening or collapsing due to human-induced climate change.
Examination of the North American sedimentary record by Nana Yobo and colleagues indicates that volcanic activity triggered this AMOC-related cooling period.
“Temperatures in the Northern Hemisphere may have dropped several degrees, changing ecosystems and forcing early humans to adapt to colder and changing environments,” Nana Yobo said.
Nana Yobo said that while the Younger Dryas is a much more sudden change than what is happening now, it shows how sensitive AMOC is to climate change.
How did volcanoes change AMOC?
Nana Yobo said the volcanic eruption cooled the Earth’s surface by blocking sunlight and disrupted the temperature and salinity of the North Atlantic, the main drivers of the AMOC, leading to the slowdown. Evidence also points to a weakening of AMOC, but not a complete collapse.
Is this the first study to suggest that volcanoes influence the AMOC?
“No, but this is one of the first examples of using geochemical evidence to link ice core eruption clusters and sediment records across North America during the Younger Dryas period,” Nana Yobo said in an email to USA TODAY.
