Sea-level change Main influences: 1 Warming of the water Thermal - - PowerPoint PPT Presentation

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Sea-level change Main influences: 1 Warming of the water Thermal - - PowerPoint PPT Presentation

Nov 16, 2022 164 likes •252 views

Sea-Level Projections Eelco J Rohling, ANU Seldom in the headlines, but the ocean is critical Famous: Global surface temperatures Almost Invisible: Ocean heat uptake Zetta = 10 21 Well over 90% of all the heat is going into warming the oceans

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Sea-Level Projections Eelco J Rohling, ANU

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Famous: Global surface temperatures Almost Invisible: Ocean heat uptake

Zetta = 1021

Well over 90% of all the heat is going into warming the oceans But oceans have vast heat capacity è their temperature increases very slowly.

Seldom in the headlines, but the ocean is critical

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Sea-level change

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Main influences: 1 – Warming of the water “Thermal expansion of water”: +0.4 m for every 1 °C temperature rise over the entire ocean depth of 3.7 km. 2 – Melting of land ice, and melt/icebergs entering the seas Addition of water to the oceans ‘fills them up’ more.

  • Mountain glacier melt – at most about 40 cm sea-level rise if all disappear (~ by 2100)
  • Continental ice sheets – Max. inputs: Greenland 7 m; East Antarctica 53 m; West Antarctica 5 m

Eelco J Rohling, ANU

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Sea-level change

3 Greenland: If linear, 0.7 cm in 10 years = 7 cm per century. BUT: rate of loss is increasing, so will be (much) more.

Eelco J Rohling, ANU

Antarctica: If linear, 0.35 cm in 10 years = 3.5 cm per century. BUT: rate of loss is increasing.

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Existing sea-level projections for 2100

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CMIP-5 = IPCC AR5 ObsHist = fully constrained by historical observations Only processes included that have acted in historical times. Any new/additional processes will increase estimates.

Goodwin et al., Earth’s Future, 2017

Eelco J Rohling, ANU

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Impacts

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Factor of increase of extreme (>99th percentile) sea-level events 10,000x means that a current once-a-century flooding level is reached every time at normal high tide

Goodwin et al., Earth’s Future, 2017

Eelco J Rohling, ANU

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New work includes unprecedented processes

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Eelco J Rohling, ANU

http://www.bitsofscience.org/wordpress-3.0.1/ wordpress/images/2016/09/greenland-ice-sheet- melting-feedbacks.jpg DeConto & Pollard, Nature, 2016 http:// www.scientia.global/ wp-content/uploads/ 2017/05/page-3- image-1.jpg https://nsidc.org/sites/ nsidc.org/files/images/ iceshelf_locations.png

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First projections including unprecedented processes…

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Eelco J Rohling, ANU

NOAA Technical Report NOS CO-OPS 083, 2017

  • ld maximum

— = business as usual pathway