4 ms·

I am a former geophysicist, and credibly we could see on the order of an 8C rise this century. It's much worse than the general public thinks, and the picture k

by cultus 6y ago

I am a former geophysicist, and credibly we could see on the order of an 8C rise this century. It's much worse than the general public thinks, and the picture keeps worsening as understanding of the system and its feedbacks increase. A rise of 5-8C make large parts of the Earth uninhabitable and would collapse food production and global civilization. Billions dying is not scaremongering, but is a very probable outcome of business-as-usual. Our civilization, and our population of 9 billion, takes an immense amount of resources to maintain, and it will collapse if the Earth can no longer supply it.

waynecochran 6y ago
5-8C is much higher than most scientific projections. https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature-projections https://www.climate.gov/news-features/understanding-climate/...
- cultus 6y ago
  Yes, but it is possible due to a number of feedback effects that are still very, very poorly constrained. It's a low-probability risk, but the damage if it occurs is literally apocalyptic. We should plan for it, just like how people wear seat belts even if they usually don't get into car wrecks. Also, government websites like climate.gov typically don't have the most current information.
SpicyLemonZest 6y ago
The IPCC says that the worst case scenario is a 5C rise, and their analysis of food production (https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap7_FINAL.pdf https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap...) doesn't indicate any sort of catastrophic collapse. What source are you getting this information from?
- cultus 6y ago
  e.g. https://www.nature.com/articles/s41561-019-0310-1 https://www.nature.com/articles/s41561-019-0310-1 The IPCC report is rather out of date at this point. There's a number of positive feedback mechanisms such as cloud cover and methane clathrates that are still poorly constrained and could credibly lead to a rise like that. It's not the most likely scenario, on the high end of current projections, but it should be planned for. You buy fire insurance for your house even if you don't think it will catch on fire. I wear a seatbelt even though the vast majority of times I'm in a car, I don't get in a crash. We rationally prepare for unlikely but severe events all the time. With climate change, people have this blind spot with thinking about risk. Here, it's the planet and our civilization. We should take existential threats very, very seriously.
  - SpicyLemonZest 6y ago
    This article is describing a rise of 8C only in some specific areas. That's a very different thing; there are all sorts of localized rises of 8C, and most of them don't matter. We should definitely take existential threats seriously, but part of that seriousness requires us to be rigorous about what we call existential. If we go around calling things existential threats when they're merely bad, the truly existential threats won't be taken as seriously as they deserve or get the attention they require. Temperature rises in particular are strange to present as an existential threat, because we have pretty solid ideas (see https://www.forbes.com/sites/jamesconca/2017/06/22/seeding-the-clouds-should-we-mess-with-our-earths-climate/#19a5724d696c https://www.forbes.com/sites/jamesconca/2017/06/22/seeding-t... for a general review) for how we could quickly force the temperature down if we absolutely had to.
    - cultus 6y ago
      It literally says 8C average surface warming globally in the abstract, just a few sentences in: "In addition to the warming from rising CO2 levels, this instability triggers a surface warming of about 8 K globally and 10 K in the subtropics. Once the stratocumulus decks have broken up, they only re-form once CO2 concentrations drop substantially below the level at which the instability first occurred." edit: There are also a tremendous amount of problems with all proposed geoengineering solutions. They are uniformly an emergency backup, not something we should ever choose. The most realistic option, sulfur dioxide in the stratosphere, needs to be maintained continually to avoid a sudden onset of warming. It also does nothing for ocean acidification from CO2 or the cognitive problems higher concentrations cause. Thinking that we can just tech-magic our way out of this is very dangerous. This will require hard choices. It would have been 100 times easier if we just started 30 years ago, but it will be 100 times harder if we wait another 10.

by cultus 6y ago

waynecochran 6y ago

5-8C is much higher than most scientific projections. https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature-projections https://www.climate.gov/news-features/understanding-climate/...

cultus 6y ago
Yes, but it is possible due to a number of feedback effects that are still very, very poorly constrained. It's a low-probability risk, but the damage if it occurs is literally apocalyptic. We should plan for it, just like how people wear seat belts even if they usually don't get into car wrecks. Also, government websites like climate.gov typically don't have the most current information.

SpicyLemonZest 6y ago

The IPCC says that the worst case scenario is a 5C rise, and their analysis of food production (https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap7_FINAL.pdf https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap...) doesn't indicate any sort of catastrophic collapse. What source are you getting this information from?

cultus 6y ago
e.g. https://www.nature.com/articles/s41561-019-0310-1 https://www.nature.com/articles/s41561-019-0310-1 The IPCC report is rather out of date at this point. There's a number of positive feedback mechanisms such as cloud cover and methane clathrates that are still poorly constrained and could credibly lead to a rise like that. It's not the most likely scenario, on the high end of current projections, but it should be planned for. You buy fire insurance for your house even if you don't think it will catch on fire. I wear a seatbelt even though the vast majority of times I'm in a car, I don't get in a crash. We rationally prepare for unlikely but severe events all the time. With climate change, people have this blind spot with thinking about risk. Here, it's the planet and our civilization. We should take existential threats very, very seriously.
- SpicyLemonZest 6y ago
  This article is describing a rise of 8C only in some specific areas. That's a very different thing; there are all sorts of localized rises of 8C, and most of them don't matter. We should definitely take existential threats seriously, but part of that seriousness requires us to be rigorous about what we call existential. If we go around calling things existential threats when they're merely bad, the truly existential threats won't be taken as seriously as they deserve or get the attention they require. Temperature rises in particular are strange to present as an existential threat, because we have pretty solid ideas (see https://www.forbes.com/sites/jamesconca/2017/06/22/seeding-the-clouds-should-we-mess-with-our-earths-climate/#19a5724d696c https://www.forbes.com/sites/jamesconca/2017/06/22/seeding-t... for a general review) for how we could quickly force the temperature down if we absolutely had to.
  - cultus 6y ago
    It literally says 8C average surface warming globally in the abstract, just a few sentences in: "In addition to the warming from rising CO2 levels, this instability triggers a surface warming of about 8 K globally and 10 K in the subtropics. Once the stratocumulus decks have broken up, they only re-form once CO2 concentrations drop substantially below the level at which the instability first occurred." edit: There are also a tremendous amount of problems with all proposed geoengineering solutions. They are uniformly an emergency backup, not something we should ever choose. The most realistic option, sulfur dioxide in the stratosphere, needs to be maintained continually to avoid a sudden onset of warming. It also does nothing for ocean acidification from CO2 or the cognitive problems higher concentrations cause. Thinking that we can just tech-magic our way out of this is very dangerous. This will require hard choices. It would have been 100 times easier if we just started 30 years ago, but it will be 100 times harder if we wait another 10.