I think you are seriously underestimating the impacts that worldwide crop failures in the next 20 years are going to have as far as global human catastrophes go.
Significant crop failures will cause prices to rise, which will enable the wider use of refrigerated storage, fertilizer, new crop varietals, desalinated water, greenhouses, etc. This will bring supply and demand back into balance at a higher price.
The higher price for food will cause millions of deaths, an impact comparable to COVID or to the Ukraine and Ethiopian wars combined. It will pale in comparison to the impact of WW2, the black plague or the Chinese cultural revolution.
it's difficult to articulate the (IMO correct) position that climate change is horrible but still totally solvable. somehow people hear "we can solve this" as " there's no reason to be concerned"
I agree with the gist of your argument, but I wouldn't phrase it as "totally solvable". Limiting it to 2 degrees is possible, limiting it to 3 is likely. Both are bad, both are locally catastrophic but neither are globally catastrophic.
I like my phrasing "millions will die". That works on numerate people, but most people can't really conceptualize the difference between a million and a billion. Any other suggestions?
There's a certain group of people that take the absolute worst predictions of climate science and just runs with it. Granted, there's a far larger group of people that think we'll be ok with business as usual. Neither is true.
I'm using BAU loosely here. I'm not referring to RCP 8.5. I have my own issues with the IPCC's estimates relying to much on direct air capture, but I don't think 5-6c is likely unless there's an unforseen feedback loop we haven't factored in.
I'd almost bet money on the eventual use of stratospheric sulfide injection to cool the planet. It's cheap enough that even a third world country could conceivably pay for it. We have no idea what the side effects will be, but it may well be worth the risk to avoid 3-4c of warming.
I work with climatologists in the development of AI models that improve over the climatology.
The amount of arable land that will be lost in the tropics is going to dramatically impact all countries around the Equator. Some areas simply will not support human life without air conditioning with a 2 degree increase in wet bulb temperature and +3C increase in extreme weather events.
Crop failures are linked to many historically extreme events. A 15%-30% in staple foods has _massive_ impacts in the poorest 20% of the population. In poor democracies it leads to people voting for demagogues and autocrats; in other places it's much worse.
The cascade of these events with ever increasing temperature is exponential.
The soil quality there is very low. Also, large parts of canada are covered by the 'canadian shield' which is basically where glaciers have scraped down to bare granite bedrock. If we had thousands of years to adjust, I'm sure we could manage but you're not planting huge fields of wheat, corn or soybean in that soil.
Those area are limited by the number of hours of sunlight and the number of growing seasons. Reductions in 20-30% are expected, but this doesn't really capture the increase in extreme weather events that can lead to total crop loss.
The higher price for food will cause millions of deaths, an impact comparable to COVID or to the Ukraine and Ethiopian wars combined. It will pale in comparison to the impact of WW2, the black plague or the Chinese cultural revolution.