Is a critical system of ocean currents headed toward an imminent collapse?
Like the 60,000 miles of arteries and veins that course throughout the human body, ocean currents are the lifeblood of our planet-some flowing short distances, others circling the globe, but all playing a critical role in regulating climate. One of the most complex system of currents, the Atlantic Meridional Overturning Circulation, or AMOC, is a global conveyor belt, distributing heat throughout the Atlantic by carrying warmer waters north and cooler waters south. "For the Earth's climate to remain in equilibrium, there has to be a huge transport of heat from low to high latitudes by the combined atmospheric and oceanic circulations,” said William Johns , a professor of ocean sciences at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science , who uses long-term moored instrumentation to study ocean circulation. "In the northern hemisphere, the AMOC accounts for nearly 25 percent of that heat transport on a global basis. It is unique in the global oceans because the Atlantic is the only place where warm surface waters move northward all the way from the tropics to polar latitudes and are cooled and sink to great depths. Those deep waters, he explained, then move southward underneath the warm layer, forming a meridional "overturning” circulation that scientists call the AMOC. "The amount of heat it carries is almost unimaginable to most people,” said Johns, noting that the value is a little over 1015 watts. "That's a 1 followed by 15 zeroes, or a quadrillion watts, which is about 100 times the total global energy production on Earth from all power sources. But is the AMOC, which affects patterns of drought and flooding, headed toward a collapse by the middle of this century?
