to me, these heatwaves feel like the start of the end of human existence
People one or two generations before you felt that about the cold war.
However while apocalypse scenarios (Nuclear war, asteroid impact, AI powered biological warfare) are low likelihood, extreme impact, climate change is extreme likelihood and high impact, not just the immediate effect on places like Europe, Canada etc, but also from the conflicts that climate change will drive, which in turn may escalate to those extreme impact nuclear wars.
On a 5x5 matrix, grand extinction events would be a 5 for effect but a 1 for likelihood, putting them in a "medium-high" category
Climate change is a 3-4 on effect but a 4-5 o likelihood, putting them in a "very-high" risk category