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Maybe the boundary isn't "discrete" or a "bright red sharp line". But for climate change, haven't relevant experts been saying for some time that effects _aren'

by abeppu 3y ago

Maybe the boundary isn't "discrete" or a "bright red sharp line". But for climate change, haven't relevant experts been saying for some time that effects _aren't_ linear because of feedback loops? If each of several such feedback mechanisms has a 'steep' region where small differences can be amplified, then there may be multiple 'soft' boundaries. I think the non-science part of this is we can't know with certainty where these feedback loops kick in until a while after we've already crossed them. But just b/c we can't know with certain where the boundaries are ahead of time doesn't mean it isn't really stupid to be cavalierly charging off into uncharted territory.

mlyle 3y ago
You may not know where the boundaries are exactly, but you can come up with bounds: lower bounds are places where Earth has spent a lot of time in the geological record in regimes that are compatible with human life; upper bounds where known terrible effects are guaranteed to happen.
- abeppu 3y ago
  What's an example of a useful known upper bound where terrible effects are guaranteed but we haven't had to actually live through them? Naming that we don't know the specific values is important; given the stakes at play, the fact that we don't know where they are ought to push us to stay close to the lower bounds. If we want to discover where the boundaries are, we can, but only at great cost.
  - mlyle 3y ago
    E.g. a value of CO2 where by direct radiative forcing, without feedback, terrible stuff happens.
    - abeppu 3y ago
      Right, so for the purposes of predicting what will happen on our actual planet, on which our continued existence is dependent, this is a very loose upper bound right? I'm not claiming that knowledge of where the boundary values lie is somehow epistemically unavailable. But there's some important, lower, unknown value, beyond which a bunch of very bad stuff will already happen, and learning the exact values through experience is extremely costly. In the context of responding to this report which is saying "we have already crossed the boundaries! (and we should immediately try to course correct)" rather than squabbling about "well, do you really know the boundary on each of these factors", I think the more honest and pragmatic reframing is to say "we don't know where the boundaries are, but we're headed rapidly away from the known safe region, and we should turn back immediately."

by abeppu 3y ago

mlyle 3y ago

You may not know where the boundaries are exactly, but you can come up with bounds: lower bounds are places where Earth has spent a lot of time in the geological record in regimes that are compatible with human life; upper bounds where known terrible effects are guaranteed to happen.

abeppu 3y ago
What's an example of a useful known upper bound where terrible effects are guaranteed but we haven't had to actually live through them? Naming that we don't know the specific values is important; given the stakes at play, the fact that we don't know where they are ought to push us to stay close to the lower bounds. If we want to discover where the boundaries are, we can, but only at great cost.
- mlyle 3y ago
  E.g. a value of CO2 where by direct radiative forcing, without feedback, terrible stuff happens.
  - abeppu 3y ago
    Right, so for the purposes of predicting what will happen on our actual planet, on which our continued existence is dependent, this is a very loose upper bound right? I'm not claiming that knowledge of where the boundary values lie is somehow epistemically unavailable. But there's some important, lower, unknown value, beyond which a bunch of very bad stuff will already happen, and learning the exact values through experience is extremely costly. In the context of responding to this report which is saying "we have already crossed the boundaries! (and we should immediately try to course correct)" rather than squabbling about "well, do you really know the boundary on each of these factors", I think the more honest and pragmatic reframing is to say "we don't know where the boundaries are, but we're headed rapidly away from the known safe region, and we should turn back immediately."