Why in the News?
A new study warned that the collapse of the Atlantic Meridional Overturning Circulation (AMOC) is no longer a low-likelihood scenario.
What is AMOC?
- Overview: It is a large system of ocean currents, part of the thermohaline circulation (THC) or global ocean conveyor belt.
- Function: Moves warm tropical surface waters northward.
- Deep Currents: In the North Atlantic, cooled water sinks and flows back south as deep currents.
- Global Link: Connected to the Antarctic Circumpolar Current, making it part of a worldwide circulation system.
- Key Role: Distributes heat and nutrients across the world’s oceans.
Why is AMOC slowing down?
- Melting Ice Sheets: Greenland and Arctic ice melt releases freshwater, lowering seawater density, preventing sinking, and weakening circulation.
- Indian Ocean Warming (2019 Study): Extra rainfall in the Indian Ocean reduces rainfall in the Atlantic.
- Temporary Boost: Atlantic water becomes saltier, sinks faster, giving AMOC short-term strengthening.
- Future Outlook: Effect fades once Pacific and other oceans catch up in warming.
- Climate Models: Predict a 34–45% weakening of AMOC by 2100 under continued global warming.
What happens if AMOC collapses?
- Severe Cooling: Europe and the North Atlantic would face strong cooling.
- Rainfall Reduction: Decline in rainfall over Europe.
- ENSO Impact: Altered El Niño–Southern Oscillation patterns.
- Sea Ice Expansion: Increase in Greenland–Iceland–Norwegian seas.
- Rain-belt Shift: Southward movement over the tropical Atlantic.
- Long-term Impact: Global climate instability with regional extremes.
| [UPSC 2012] Consider the following factors:
1. Rotation of the Earth 2. Air pressure and wind 3. Density of ocean water 4. Revolution of the Earth Which of the above factors influence the ocean currents? Options: (a) 1 and 2 Only (b) 1, 2 and 3* (c) 1 and 4 (d) 2, 3 and 4 |
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