![]() ![]() There, the water sinks, and then crawls across the bottom of the ocean, miles/kilometers deep, over hundreds of years, gradually rising in the Pacific and Indian oceans. Warm water flows along the surface until it reaches one of a few special spots near Greenland or Antarctica. The general thermohaline circulation is a pattern of water flow through the world's oceans. The Atlantic meridional overturning circulation (AMOC) is part of a global thermohaline circulation in the oceans and is the zonally integrated component of surface and deep currents in the Atlantic Ocean. ![]() Overall structure AMOC in relation to the global thermohaline circulation (animation) On the other hand, paleoceanographic research suggests that the AMOC may be even more stable than what is assumed by most models. One of those lower-complexity projections suggests that AMOC collapse could happen around 2057, but many scientists are skeptical of the claim. Earth system models used in Coupled Model Intercomparison Project indicate that shutdown is only likely after high levels of warming are sustained well after 2100, but they have been criticized by some researchers for what they saw as excessive stability, and a number of lower-complexity studies argue that a collapse can happen considerably earlier. A shutdown would have far greater impacts than a slowdown on both the marine and some terrestrial ecosystems: it would lower the average temperature and precipitation in Europe, slashing the region's agricultural output, and may have a substantial effect on extreme weather events. Severe weakening of the AMOC has the potential to cause an outright collapse of the circulation, which would not be easily reversible and thus constitute one of the tipping points in the climate system. Climate models consistently project that the AMOC would weaken further over the 21st century, : 19 which would affect average temperature over areas like Scandinavia and Britain that are warmed by the North Atlantic drift, as well as accelerate sea level rise around North America and reduce primary production in the North Atlantic. Oceanographic reconstructions generally suggest that the AMOC is already weaker than it was before the Industrial Revolution, although there is a robust debate over the role of climate change versus the circulation's century-scale and millennial-scale variability. The AMOC is an important component of the Earth's climate system, and is a result of both atmospheric and thermohaline drivers.Ĭlimate change has the potential to weaken the AMOC through increases in ocean heat content and elevated freshwater flows from the melting ice sheets. These "limbs" are linked by regions of overturning in the Nordic and Labrador Seas and the Southern Ocean, although the extent of overturning in the Labrador Sea is disputed. It is characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder, deep waters. The Atlantic meridional overturning circulation ( AMOC) is part of a global thermohaline circulation in the oceans and is the zonally integrated component of surface and deep currents in the Atlantic Ocean. Colors of curves indicate approximate temperatures. Topographic map of the Nordic Seas and subpolar basins with surface currents (solid curves) and deep currents (dashed curves) that form a portion of the Atlantic meridional overturning circulation. For other uses, see AMOC (disambiguation). ![]()
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