That is hardly an uninhabitable world. It might be a very different world, with all sorts of new issues to deal with. But not uninhabitable.
Unfortunately (for us) it does look like newer predictions predict worse outcomes with higher confidence [1].
PS: yes scientific consensus changes over time as a function of available measurement data and understanding. That's not a sign of failure but of improved scientific insight.
[1] https://www.counterpunch.org/2020/03/18/the-ipccs-worst-case...
Things have pretty much been consistently worse than predicted.
Seriously, it's going to suck and cause many, many issues. But the planet won't be completely uninhabitable for many centuries, if it ever even happens, through man made climate change.
Do you remember the Syrian refugee crisis and how it destabilized pretty much all of Europe and how we're still dealing (or failing to deal) with the political consequences of these upheavals?
How do 1.5 billion migrations by 2050 sound to you? Yeah. Many many issues.
And I'm not even going into the discussion that the whole planet will be toast once we reach +5 degrees celsius, which looks more and more not only like a extreme outlier but a real possibility instead.
Fun times ahead.
Their "best guess" isn't very good. What's your best guess for the number of COVID cases in your area in 2 months?
Things could be significantly worse than IPCC's estimate, or not that bad. We really don't know. From that uncertainty we should begin to think about things we can do to limit risk.
When there's relatively unbounded downside, you buy insurance (of various forms, financial, operational and other).
IPCC models don't take into account the feedback loops. Also , things are moving faters alredy that they have been anticipating, so expect these predictions to be completely obsolte in few years.
* The models are continuously updated. Recent measurements of land surface temperatures and polar ice sheets have been tracking worst case scenarios, not the previous expected mean (see e.g. Arctic ice sheet melt-off in 2020). * There are considerable confidence intervals around predicted temperature increases and related forecasts, e.g. GDP growth. * There are considerable nonlinear dynamics such as thawing permafrost or sea-floor deposits of methane, or death of carbon sinks such as forests. This means that the outcomes of the models can diverge wildly from the mean expected outcome. * I believe IPCC models do not take into account the political upshot of massive loss of farmland and habitable land in the tropics (i.e., refugees and wars).
Add that to the massive ecosystem disruptions that are already taking place, add the political unrest that will follow from the tsunami of migrants that are trying to just survive and you have the perfect ingredients for an pretty much uninhabitable planet.
Maybe not in the next 25 years. The next 25 years we will just have massive unrest, political upheaval, wars, ecosystem collapse and genocides.
I'm not so optimistic about the 25 years after that, though.
Statements like this can be problematic because while the world in general may still be inhabitable, there could be particular regions that are not, or the damage cause by climate change can be too much for the people living there to deal with.
For example: right now Karachi, Pakistan, population 15M, seems to be basically totally underwater:
* https://www.theguardian.com/world/2020/aug/26/pakistan-flood...
* https://www.dw.com/en/flooding-causes-havoc-in-karachi/a-547...
Tuvalu and the Marshal Islands are predicted to basically disappear:
* https://www.theguardian.com/global-development/2019/may/16/o...
* https://en.wikipedia.org/wiki/Effects_of_climate_change_on_i...
Some regions may not have the fiscal/political capital to deal with the changes wrought by climate change, and it is often the regions that did the least cause climate change that suffer the most. Most of the historical emissions that got us here were produced by the industrialized West (especially US), but they'll probably be bit the least-hard.
Just because certain political factions make climate change into a hysterical issue, doesn’t mean that this is actually scientifically accurate.
On the other hand, global warming, probably will have second order effects that make humanity extinction more probably. For example: it would make nuclear war more probable or investment in space more difficult.
A warming planet as we've seen also makes viruses more prevalent as we invade natural habitats and expand to more food sources... (we may need to hunt all animals for food someday, including apes, tigers, monkeys, etc.. )...
Honestly, I think the best solution is a full stop on consumerism, and all industries and combine forces and resources to find a solution that will work like - a big effing huge solar shade that can cool off the planet and maybe put us in a small mini-ice-age to bring back some polar ice, and ice in antarctica and essentially reboot the global temps.
Carbon capture tech and methane capture will be important too, but the feedback loops are going to be what really speeds things up.
Warming planet also means more water evaporation, so we'll need to desalinate water just to be able to have drinking water for everybody. Water wars are going to be the biggest fights of the next 40 years.