The story
After the Last Glacial Maximum about 26,000 years ago the great ice sheets began to melt, and sea level rose by about 120 metres by about 7,000 years ago. The rise was not smooth. Coral records off Tahiti, analysed by Pierre Deschamps and colleagues in 2012, show that around 14,650 to 14,300 years ago, sea level jumped about 14 metres in about 340 years, roughly 4 centimetres a year. This is called Meltwater Pulse 1A.
The pulse began close to the warm Bolling-Allerod interval. The source of the water is debated. Some studies point to the Laurentide and Eurasian ice sheets, others to Antarctica, and many conclude that several ice sheets contributed. The rise drowned coastlines, flooded the shallow shelves that had formed land bridges, and began to separate islands from continents. It also changed ocean circulation, since freshwater flooding the North Atlantic can slow the currents that carry warmth north. Rapid sea level rise is also what scientists fear from today's melting ice sheets.
Why it mattered
- The pulse is the best natural example of how fast sea level can rise when ice sheets collapse.
- It drowned coastal land and helped to isolate places such as the British Isles.
- It helps to test models for the stability of today's ice sheets.
Sources
- Ice-sheet collapse and sea-level rise at the Bolling warming 14,600 years ago (Deschamps et al., Nature 2012) Nature / WHOI
- Ice-sheet collapse and sea-level rise at the Bolling warming 14,600 years ago University of Oxford
- Sea-level constraints on the amplitude and source distribution of Meltwater Pulse 1A Nature Geoscience
- A reconciled solution of Meltwater Pulse 1A sources using sea-level fingerprinting Nature Communications
- The Big Melt University of Texas Marine Science Institute
Contested history
Consensus: Sea level rose several metres within centuries about 14,600 years ago; the source of the water is argued.
- A reconciled solution of Meltwater Pulse 1A sources using sea-level fingerprinting Nature Communications
- The Big Melt University of Texas Marine Science Institute
Community notes
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