I don't see how the grandparent comment implied a lack of trust in other experts, nor did they imply themselves to be experts.
> Catastrophic collapse is not really something generally assumed on the 2-3 degree warming path.
Actually, the IPCC, which tends to be rather optimistic on how bad things could be (or already are), predicts pretty significant socioeconomic problems arising from 2-3 degrees warming: https://en.wikipedia.org/wiki/Shared_Socioeconomic_Pathways
It doesn't take much imagination to come up with ways that "Social cohesion degrades and conflict and unrest become increasingly common" leads to "nation states with nukes and experiencing extreme scarcity and high social unrest declare war on each other"...