15 votes

This is what 3°C of global warming looks like

8 comments

  1. [6]
    Eric_the_Cerise
    Link
    When you watch this, remember that we probably won't hit 3°C. OTOH, barring significant changes, we probably will get very close. 2.8°C will suck almost as much. Not that long ago, 1.5°C was our...

    When you watch this, remember that we probably won't hit 3°C. OTOH, barring significant changes, we probably will get very close. 2.8°C will suck almost as much.

    Not that long ago, 1.5°C was our line-in-the-sand target, and 2.0°C was the 'doomsday' scenario. Now, 2.0°C is, roughly, our best-case.

    3 votes
    1. [3]
      spit-evil-olive-tips
      Link Parent
      if you believe in the methane clathrate gun hypothesis, there's a certain level of warming above which a positive feedback loop is created and runaway warming is more or less unstoppable. so even...

      if you believe in the methane clathrate gun hypothesis, there's a certain level of warming above which a positive feedback loop is created and runaway warming is more or less unstoppable.

      so even if our CO2 emissions create "only" 2.8 C of warming, that might release enough methane to add on an extra 0.1C. which in turn releases a bit more methane...

      but if the clathrate gun were real there would probably be early warning signs. things like methane bubble plumes from the ocean and massive craters appearing suddenly in the Siberian used-to-be-permafrost.

      4 votes
      1. vektor
        Link Parent
        My reading of that wiki article is that methane release happens way too slowly to meaningfully affect the current climate change timeline and is also much too weak. For example, atmospheric...

        My reading of that wiki article is that methane release happens way too slowly to meaningfully affect the current climate change timeline and is also much too weak. For example, atmospheric methane levels currently vs. pre-industrial times: Even with CO2 being our prime concern, we have put so much methane into the atmosphere, it dwarfs what we currently think the clathrate gun could do.

        I don't think it's reasonable to assume that this feedback loop is powerful enough to feed itself, at least not in the time spans we care about. To continue your thought experiment: the 0.1C additional temp releases a bit more methane, which is enough to raise the temperature another 0.03C, which releases a tiny bit more methane, which only contributes marginally to temperature. It might be that more methane is released over a longer period, but frankly if we can keep human society intact through the next 100 years, I don't think climate change will be a concern anymore.

        If I'm not entirely mistaken, natural climate change has always happened very slowly, so I don't think there's reason to assume there are overwhelming fast-acting feedback loops at work.

        That's not to say there's no methane being released. I just doubt the scale is anywhere near the destruction we do all by ourselves.

      2. Eric_the_Cerise
        Link Parent
        The idea that we might push Earth into some new, higher, equilibrium state (that might look more like, eg, Venus) is certainly possible. But I don't think we have much evidence of that possibility...

        The idea that we might push Earth into some new, higher, equilibrium state (that might look more like, eg, Venus) is certainly possible. But I don't think we have much evidence of that possibility in the Earth's history, so I think any kind of really extreme self-perpetuating feedback loop is unlikely, although I do also think the Atlantic warm-water conveyor-belt thingy (I forget the proper name) may well shut down, which would be borderline catastrophic for modern civilization.

        And yeah, we have already triggered many natural processes that are exacerbating the situation.

    2. [2]
      joelthelion
      Link Parent
      Any evidence to support this? IIRC, the "business as usual" hypothesis, which we are more or less following regardless of what leaders are saying, goes to 3 °C and beyond. I certainly hope major...

      When you watch this, remember that we probably won't hit 3°C

      Any evidence to support this? IIRC, the "business as usual" hypothesis, which we are more or less following regardless of what leaders are saying, goes to 3 °C and beyond. I certainly hope major policy changes will occur soon throughout the world, but so far I don't see them happening, or at least not fast enough.

      3 votes
      1. Eric_the_Cerise
        Link Parent
        My nutshell response is, basically, if world leaders honor the commitments they've made to date, and also do not make any more commitments (both doubtful, but somewhat counterbalancing), we're on...

        My nutshell response is, basically, if world leaders honor the commitments they've made to date, and also do not make any more commitments (both doubtful, but somewhat counterbalancing), we're on track for a, best-guess, 2.7°C increase.

        Sorry, I don't recall any specifics that support that, but it has been my impression over the past several months leading up to this conference.

  2. [2]
    joelthelion
    Link
    @mycketforvirrad not very important, but the video, which is the important part of this link, is not behind a paywall.

    @mycketforvirrad not very important, but the video, which is the important part of this link, is not behind a paywall.

    2 votes
    1. mycketforvirrad
      Link Parent
      Duly noted. I have removed the paywall.hard tag.

      Duly noted. I have removed the paywall.hard tag.

      2 votes