Multimillennial Sea-Level Commitment Associated with Global Warming

A recent study in the Proceedings of the National Academies of Science (open access article) assesses prospective sea-level rise over the course of the next 2000 years, combining paleo-reconstructions of sea-level rise and simulations from physical models focusing on the four main components that contribute to sea-level change.

Among the study’s findings:

  1. Thermal expansion yields a global mean sea-level rise of 0.38m with a homogenous increase of ocean temperature by 1C;
  2. The total contribution of all glaciers (all land ice excluding ice sheets) to sea-level rise over the next 2000 years is ~0.6m;
  3. The potential contribution of the Greenland Ice Sheet is projected to be 0.18m °C-1 up to a 1C temperature increase and 0.34m °C-1  for temperature increases between 2-4C;
  4. Simulated temperature rise over the next two millennium yields a 1.2m rise in sea level associated with melting of the Antarctic Ice Sheet;
  5. On a 2000 year time scale, the contribution of the sources outlined above will be largely independent of the projected warming path during the first century;
  6. The total sea-level commitment from all sources is 2.3m °C-1 over 2000 years. However, the melting of the Greenland Ice Sheet ultimately results in 6m of sea-level rise over the course of several ten thousand years.

This study could stimulate some good classroom discussion. Some potential questions:

  • In the context of questions of inter-generational equity, do these potential impacts substantially expand the scope of generations whose interests must be acknowledged and protected?;
  • What are the implications of projected long-term rises in sea-levels for adaptation initiatives?
  • What are the most significant sources of uncertainty associated with paleo-climatic sea level rise and temperature records?

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