This paper challenges the idea that 1.5 is a safe amount of climate change to save the coasts. They find that the safe threshold was around 1°. Even net zero will raise sea levels. They also find that the interglacial paleorecord downplays the true risk of modern day CO2 forcing on the ice sheets.

  • fake_meows@sopuli.xyzOP
    2·
    4 months ago

    Surely “net zero” will put the brakes on sea level rise?

    No, that’s not what they report.

    Over longer timescales, the committed median sea level rise […] has been estimated at +0.7 m to +1.2 m, even if net zero greenhouse gas emissions are sustained until 2300, but ~3 m from Antarctica could not be ruled out.

    /Furthermore, each 5-year delay in near-term peaking of CO2 emissions increased median SLR at 2300 by around +20 cm, and no net zero scenario gave a median SLR below +1.2 m at 2300 once global mean temperatures exceed +1.5 °C.

    Based on the CO2 already in the atmosphere, we are looking at major sea level rise. It takes a while to happen.

    What this says is that every 5 years of Business as Usual before we get to net zero, we commit to another 20cm of rise.

    Net zero starting today could still be as much as 3m of rise in the pipeline over the next generations.

    Due to the hysteresis in the system, if we actually wanted to cancel sea level rise, to refreeze the poles takes an even bigger signal in the opposite direction. So to over power the warming trend we would have to get CO2 down even more below pre-industrial than we raised it.