The general view shows the Atlantic Ocean near the road between Saint-Jean-De-Luz and Hendaye, in Socoa, France, February 2, 2019.
REUTERS / Régis Duvignau
The current Atlantic Ocean system, which drives the northern hemisphere’s climate, could weaken to such an extent that it could soon make big changes to global weather, according to a scientific study on Thursday.
The Atlantic Meridional Reversing Circulation (AMOC) is a large system of ocean currents that carries warm water from the tropics north into the North Atlantic.
As the atmosphere warms due to increased greenhouse gas emissions, the underlying ocean surface retains more heat. A potential system collapse could have serious consequences for the world’s weather systems.
Climate models have shown that AMOC is at its lowest for over 1,000 years. However, it is not known whether the weakening is due to a change in circulation or a loss of stability.
The study, published in the journal Nature Climate Change, said the difference is critical.
“The loss of dynamic stability would imply that AMOC has approached its critical threshold, beyond which a substantial and in practice probably irreversible transition to the weak mode could occur,” Niklas Boers told the Potstdam Institute for research on climate impact and author of the study.
Analyzing sea surface temperature and Atlantic Ocean salinity patterns, the study said the weakening of the past century is likely to be associated with a loss of stability.
“The results support the assessment that the decline in AMOC is not just a fluctuation or linear response to increasing temperatures, but likely signifies approaching a critical threshold beyond which the system traffic could collapse, ”Boers said.
If AMOC collapsed, it would increase the cooling of the northern hemisphere, sea level rise in the Atlantic, an overall decrease in precipitation in Europe and North America, and a change in monsoons in America. South and Africa, the UK Met Office said.
Other climate models have indicated that AMOC will weaken over the next century, but that a collapse before 2100 is unlikely.