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Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet

Ricarda Winkelmann, Anders Levermann, Andy Ridgwell, and Ken Caldeira · Science Advances 1 · 2015

Key finding. Burning the currently attainable fossil fuel resources, about 10,000 gigatonnes of carbon, is sufficient to render Antarctica almost ice-free, with sea-level rise averaging more than 3 m per century during the first millennium; the West Antarctic Ice Sheet becomes unstable after only 600 to 800 GtC of additional emissions.

A scatter plot of Antarctic ice loss in metres of sea-level equivalent against cumulative CO2 emissions in gigatonnes of carbon on a logarithmic axis from about 100 to 10,000. Three curves show the commitment after 1000, 3000, and 10,000 years, all rising steeply beyond about 500 gigatonnes. Inset maps of Antarctica show progressively less ice at higher emissions. A red band across the top marks the ice-free state, upper axes give peak warming, and a grey band at the right marks total fossil resources.
Sea-level commitment from Antarctic ice loss against cumulative emissions. The response is threshold-like rather than gradual, and the grey band at the right shows that the total attainable fossil resource reaches the ice-free end of the curve. Figure 2 from Winkelmann et al. (2015), Science Advances 1, e1500589. Reproduced under CC BY-NC 4.0. Extracted from the published PDF and resized for web display.

What question did this research address?

The Antarctic Ice Sheet holds water equivalent to 58 metres of global sea-level rise. Whether that ice is at risk on any timescale relevant to the fossil-fuel era had not been established.

This paper asked a deliberately simple question with a bounded answer. Are the fossil fuel resources actually available to be burned sufficient, in themselves, to eliminate the Antarctic Ice Sheet?

What did we find?

Simulations with the Parallel Ice Sheet Model show that cumulative emissions of 10,000 GtC leave Antarctica almost entirely ice-free. The associated sea-level rise exceeds an average of 3 metres per century through the first thousand years.

The threshold for irreversible loss is far lower than the total. Consistent with observations and other simulations, the West Antarctic Ice Sheet becomes unstable with only 600 to 800 GtC of additional carbon emissions.

Beyond that point, destabilization of ice basins in both West and East Antarctica produces a threshold-like increase in global sea level rather than a smooth response.

The sea-level contribution from Antarctica under unabated emissions far exceeds that of all other possible sources combined.

Why does it matter?

The result establishes that the ice sheet is not a spectator to the fossil-fuel question. The quantity of carbon required to eliminate it is not a hypothetical excursion but the resource base that exists and is, in principle, extractable.

The gap between the two numbers is where the decision lies. Eliminating the whole ice sheet takes 10,000 GtC, but committing to the loss of West Antarctica takes 600 to 800 GtC — a quantity within reach of scenarios currently under discussion.

Citation

Ricarda Winkelmann, Anders Levermann, Andy Ridgwell, and Ken Caldeira (2015). Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet. Science Advances 1.

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