The landscape of North America as we know it could be changed forever and undergo a deep-freeze, and scientists say it's all because of human-caused climate change.
Researchers recently discovered that a large system of ocean currents in the Atlantic has been disrupted, which could ultimately lead to catastrophe for North America, causing parts of the country to rapidly freeze.
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Even a partial collapse in the system, known as the Atlantic Meridional Overturning Circulation (AMOC), could cause dramatic changes in worldwide weather patterns, according to a study published Thursday in the Nature Climate Change journal.
"The Atlantic Meridional Overturning really is one of our planet's key circulation systems," study author Niklas Boers, from the Potsdam Institute for Climate Impact Research, said in a statement.
The AMOC transports warm water from the tropics northward at the ocean surface and cold water southward at the ocean bottom. It influences weather systems around the globe.
Observations and so-called fingerprints, such as sea-surface temperature and salinity patterns of the Atlantic Ocean, indicate a gradual weakening of the AMOC during the last century, according to the study.
Previous studies have show that the currents are at their slowest point in at least 1,600 years, but the new analysis shows they may be nearing a shutdown.
Boers said the evidence suggests that the AMOC may have evolved from relatively stable conditions to a point close to a critical transition, "beyond which the circulation system could collapse."
If the system collapses and shuts down, it would bring extreme cold to North America and Europe. It would also raise sea levels along the U.S. East Coast and disrupt seasonal monsoons that provide water to much of the world, the Washington Post reported. Climates from the Amazon rainforests to the Antarctic ice sheets would be impacted.
Boers said further research is needed to determine whether the AMOC weakening is due to a change in circulation or the loss of stability. A number of factors that directly effect the warming of the Atlantic ocean must also be considered, Boers added, including freshwater inflow from melting ice sheets, increasing precipitation and river run-off. All factors, he said, which are linked to human-caused climate change.
"I wouldn't have expected that the excessive amounts of freshwater added in the course of the last century would already produce such a response in the overturning circulation," Boers said. "We urgently need to reconcile our models with the presented observational evidence to assess how far from or how close to its critical threshold the AMOC really is."
Scientists can't predict if or when a possible collapse in the system might happen, but they say steps can be taken now that would decrease the likelihood of such a travesty. That includes any action to slow global warming, such as reducing greenhouse gases and carbon emissions, and using more renewable sources of energy.
