The results are fascinating. If temperatures peak at 2°C or so, and remain there, then the models – as expected – predict substantial ice sheet collapse after several thousands of years.

However, things change if warming is seriously mitigated post-2100. In those models, inertia in the ice sheet’s response – a bit like the time it takes for a ripple to settle down as it passes across a pond – means that an overshoot is at least partly reversible as long as temperatures are quickly brought back down.

The paper is here, and says:

Our results show that the maximum GMT and the time span of overshooting given GMT targets are critical in determining GrIS stability. We find a threshold GMT between 1.7 °C and 2.3 °C above preindustrial levels for an abrupt ice-sheet loss.

  • Ben Matthews
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    1 year ago

    Seems like a key new paper, but not surprising to me. It takes a long time to melt ice kilometers thick, so it’s the integral of warming that counts. However once its altitude drops below a certain level, the snow on the top becomes rain, and it can only go down.

    threshold GMT between 1.7 °C and 2.3 °C

    could be not far away now -and note also (abstract):

    even temporarily overshooting the temperature threshold, without a transition to a new ice-sheet state, still leads to a peak in SLR of up to several metres