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There are two things which have kind of cancelled out in terms of climate predictions: the worst-case CO2 emissions have not occured (mostly because growth beca

There are two things which have kind of cancelled out in terms of climate predictions: the worst-case CO2 emissions have not occured (mostly because growth became linear instead of exponential), but also a lot of the negative effects of climate change have happened sooner than expected (especially extreme weather events). The really, really bad scenarios depend either on the CO2 emissions not reaching an inflection point and decreasing (which I think will happen, but how quickly it happens will have a big impact on outcomes), or on some positive feedback mechanism kicking in, of which there are a few potential candidates but a lot of uncertainty for where the thresholds are (predictions range from 'already passed' to 'in the relatively far future'). These should neither be ignored as a possibility nor treated as inevitable.

WorldMaker 3y ago
We're still fighting to keep below the 2 degree C milestone, because we already passed the 1 degree C milestone which was the worst-case projection by some 1970s scientists. There is certainly a sense that we're not "expecting the worst-case" today because we keep inventing new "worst case" predictions instead. Also, some of the frighteningly hard to stop feedback mechanisms have started, such as glacier melting has hit some extremes that scientists feared would be points of no return. Whether this will play out in the ways of those 1970s worst case predictions we don't know, and a variable here is that we are working to avoid them (badly, but still some avoidance work is better than doing nothing). Some of that is like the Y2K problem: the self-unfulfilling prophecy. We've warned ourselves for decades what the risks are and what the worst cases are. We've put in a lot of work to mitigate/slow/stop the worst cases. We've partly failed, several times over, and had to invent new worst cases. We're still working to prevent those new worst cases. We likely will not ever hit a worst case, we're just in our own feedback loops trying to find the acceptable compromise. If the acceptable compromise "turns out alright" people will claim we never really were in danger of the worst cases, discounting the huge amounts of effort we put into avoiding it. "The prophecy was self-unfulfilled so it wasn't really a big deal was it?" "Y2K didn't happen, so why was everyone so worried about it?"

WorldMaker 3y ago

We're still fighting to keep below the 2 degree C milestone, because we already passed the 1 degree C milestone which was the worst-case projection by some 1970s scientists. There is certainly a sense that we're not "expecting the worst-case" today because we keep inventing new "worst case" predictions instead. Also, some of the frighteningly hard to stop feedback mechanisms have started, such as glacier melting has hit some extremes that scientists feared would be points of no return. Whether this will play out in the ways of those 1970s worst case predictions we don't know, and a variable here is that we are working to avoid them (badly, but still some avoidance work is better than doing nothing). Some of that is like the Y2K problem: the self-unfulfilling prophecy. We've warned ourselves for decades what the risks are and what the worst cases are. We've put in a lot of work to mitigate/slow/stop the worst cases. We've partly failed, several times over, and had to invent new worst cases. We're still working to prevent those new worst cases. We likely will not ever hit a worst case, we're just in our own feedback loops trying to find the acceptable compromise. If the acceptable compromise "turns out alright" people will claim we never really were in danger of the worst cases, discounting the huge amounts of effort we put into avoiding it. "The prophecy was self-unfulfilled so it wasn't really a big deal was it?" "Y2K didn't happen, so why was everyone so worried about it?"