Climate change leads to conflict. For example, the Syria drought of 2006-2010.
More climate change leads to larger conflicts, and large conflicts can lead to nuclear exchanges. Think about what happens if India and Pakistan (both nuclear powers) get into a major conflict over water again.
Still, like I said somewhere else, even all out nuclear war is unlikely to lead to human extinction. It could push us back to the neolithic in some scenarios, but even then there is some disagreement about what would happen.
Of course, even in the most optimistic scenario it would be really bad and we should do everything we can to avoid it - that goes without saying.
In any case, besides addressing the root cause vs. proximal cause, you couldn't even address the proximal cause anyways: it's more likely that the world could do something about climate change than about war in general.
My take is that if you remove nuclear/biological war out of the picture somehow, climate change is not an existential risk. If you remove the latter then the former is still an existential risk (and there are unfortunately a lot of other possible sources of geopolitical instability). So the fundamental source of risk if the former. But it's a matter of opinion.
Conventional or chemical warfare, even on a global scale, are definitely not existential risks though. And like I said, probably not even nuclear. Biological... that I could see leading to extinction.
The assumption we’d need to use nukes is insane. For the same cost (and energy requirements) for a set of nukes we can filter salt from ocean water or collect rain.
I agree famine and drought can cause conflict. But we are no where need that. If you read the climate change predictions (from the UN), they actually suspect more rain (and flooding) in many regions.
I was referring to the Indo-Pakistani war of 1947-1948 where the conflict focused on water rights. Nuclear weapons did not enter the picture until much later.
Earlier this year, those old tensions about water rights resurfaced:
https://www.usip.org/publications/2023/02/india-and-pakistan...
> For the same cost (and energy requirements) for a set of nukes we can filter salt from ocean water or collect rain.
The fight would be over the water flowing through the Indus, which is orders of magnitudes more than all Indian and Pakistani desalination projects combined.