A new study reveals that the speed of climate change poses a greater threat to Atlantic Ocean currents than the total amount of warming itself. Researchers found that these critical currents, which help regulate global climate patterns, can withstand temperatures rising by up to 9 degrees Fahrenheit above preindustrial levels if the warming occurs gradually. However, rapid warming at current rates could trigger a catastrophic collapse at just 3.6 degrees Fahrenheit of warming.
The Atlantic Meridional Overturning Circulation, which includes the Gulf Stream, transports heat across the Northern Hemisphere. Scientists warn that a weakened system could bring freezing conditions to Europe, worsen coastal flooding along the U.S. East Coast, and trigger droughts near the equator. The circulation depends on dense surface waters in the North Atlantic sinking to drive the system, but warming temperatures and freshwater from melting Arctic ice are interfering with this process.
Researchers conducted computer simulations comparing slow versus rapid increases in atmospheric carbon dioxide. In slow-warming scenarios, evaporation and reduced freshwater inputs allowed ocean systems to adapt and maintain current strength. Under rapid warming matching today’s emission rates, the system could not adjust quickly enough, leading to collapse at much lower temperature thresholds.
The findings suggest policymakers should consider warming rates alongside temperature targets. Researchers also caution that temporary overshooting strategies—where warming briefly exceeds targets before being reduced through carbon capture—could trigger irreversible tipping points that cannot be reversed.
Originally reported by Livescience →
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