page_title: Effects of global warming
section_title: Atlantic Meridional Overturning Circulation
hierarchical_section_title: Effects of global warming / Abrupt or irreversible changes / Atlantic Meridional Overturning Circulation
caption_attribution_description: English: This map shows the pattern of thermohaline circulation also known as "meridional overturning circulation". This collection of currents is responsible for the large-scale exchange of water masses in the ocean, including providing oxygen to the deep ocean. The entire circulation pattern takes ~2000 years. Deutsch: Thermohaline Zirkulation und die Entstehung von kaltem, dichtem Tiefenwasser im Nordmeer
context_page_description: The effects of global warming or climate damage include far-reaching and long-lasting changes to the natural environment, to ecosystems and human societies caused directly or indirectly by human emissions of greenhouse gases. It also includes the economic and social changes which stem from living in a warmer world. Human caused climate change is one of the threats to sustainability.
  Many physical impacts of global warming are already visible, including extreme weather events, glacier retreat, changes in the timing of seasonal events, sea level rise, and declines in Arctic sea ice extent. The future impact of global warming depends on the extent to which nations implement prevention efforts and reduce greenhouse gas emissions. Ocean acidification is not a consequence of global warming, but instead has the same cause: increasing atmospheric carbon dioxide.
  Climate change has already impacted ecosystems and humans as well. In combination with climate variability, it makes food insecurity worse in many places and puts pressure on fresh water supply. This in combination with extreme weather events, leads to negative effects on human health.
context_section_description: The Atlantic Meridional Overturning Circulation (AMOC). an important component of the Earth's climate system, is a northward flow of warm, salty water in the upper layers of the Atlantic and a southward flow of colder water in the deep Atlantic. Potential impacts associated with AMOC changes include reduced warming or (in the case of abrupt change) absolute cooling of northern high-latitude areas near Greenland and north-western Europe, an increased warming of Southern Hemisphere high-latitudes, tropical drying, as well as changes to marine ecosystems, terrestrial vegetation, oceanic CO
  ₂ uptake, oceanic oxygen concentrations, and shifts in fisheries.
  According to a 2019 assessment in the IPCC's Special Report on the Ocean and Cryosphere in a Changing Climate it is very likely (greater than 90% probability, based on expert judgement) that the strength of the AMOC will decrease further over the course of the 21st century. Warming is still expected to occur over most of the European region downstream of the North Atlantic Current in response to increasing GHGs, as well as over North America. With medium confidence, the IPCC stated that it is very unlikely (less than 10% probability) that the AMOC will collapse in the 21st century. The potential consequences of such a collapse could be severe.
caption: This map shows the general location and direction of the warm surface (red) and cold deep water (blue) currents of the thermohaline circulation. Salinity is represented by color in units of the Practical Salinity Scale. Low values (blue) are less saline, while high values (orange) are more saline.[223]
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