In order of magnitude:
Psychological and political consequences of climate change leading to a significantly larger likelihood of botching AI and killing all present and future humans.
I can safely assert that if the expected consequences of climate change do show up, our society will become a lot more dumber and a lot more likely to screw up on this.
Imagine mankind being as close to AGI as we will be in ten years during a political situation similar to the Cold War. Things are likely to get at least as bad if most powers feel like they have to contend resources against each other, not to mention that we are likely to get a lot of nationalist governments when the global situation will get this chaotic and people will start to panic. From there to "if we don't improve our AIs the neighbouring hated enemy will and will crush for sure" it's a pretty brief step. Not to count "but we do have to fix this mess somehow, I'm sure you have already been careful enough and we are ready to do this", "or I'm sure we have been cautious enough, people are dying as we speak, we have to do this now".
Environmental and social consequences of climate change managing to collapse the existing civilisation by putting too much stress on the vulnerable systems needed to keep it alive (especially water and food) and such stress going into a positive feedback circle, with the result of giving permanent death to any present human who hasn't already received cryogenic and hidden his body/brain somewhere safe.
From what I've seen the models on climate change consequences are overly optimistic, simply because we have no real data on what actually happens if so many things change at once in the environment. These models describe consequences like one third of all animal and vegetal species going extinct, and one billion climate refugees. These are disasters one order of magnitude greater than anything we have directly observed so far, and it's a safe bet such big changes would produce a lot other effects.
Industrial overproduction and overcompsumtion of resources.
To actually get a society that won't crash horribly for resource exhaustion before we get AGI right, with consequences similar to the above point, it's urgent that we dial back industrial production a lot.
We are overproducing so much and wasting so many resources and outputting so much unnecessary pollution that it's ridiculous.
If you actually read the report of the Ipcc their suggested solutions are, very semplified: mostly don't waste, replace everything you can with cleaner energy sources, invest heavily in trying to reabsorb excess greenhouse gasses. Most of the analysis I saw, instead, claimed the climate crisis was unsolvable because renewables couldn't possibly provide all the energy that we need RIGHT NOW, not really considering how much are we using compared to what we need.
All of this excess production and pollution isn't even doing anything positive, it's not improving out living standards in any way, it's just a waste and a way for a small percentage of very rich people/corporations to make an increased profit (which doesn't fall back in any way to the general populace, as wealth concentration and quality of life clearly shows).
But if you mention we need to use less resources and decrease industrial production some people just seem to assume that you are a Luddite or that you want everyone to go back to the caves. I think there is something similar to cheering for the technology+industry team and that's a pretty dangerous bias.