I'm also not at all convinced of the forecast of population collapse through famine etc. Any event so drastic as to kill tens of millions of people will also lead to more births surely after, as people have more kids when and after times are unstable.
I think climate events that could kill tens of millions of first world people are still decades away, unless there is a rapid collapse of the Arctic or other climate weak points. However climate events that kill tens of millions are not necesary for societal collapse. If years like the last three become the new normal, war is soon to follow. That could undo modern society faster than any other natural event short of a meteor strike. Remember that he who must not be named on this thread has the biggest button.
Climate change is just starting. I'm hoping the changes we are seeing slow down for the next few years and we get at least 5 years of a climate stability similar to that of the 20th century. I think that would be sufficient time to recover, rebuild and prepare for the next wave of extremes.
However I don't like our odds. As the globe warms and ice disappears for the rest of our lifetimes, extreme climate events become more likely. That means less time and space for recovery.
Recovery is key. During the holocene many extreme climate events happened, but they were suficiently separated from each other in both time and space that human society had time to recover, and oportunity to grow. I think the increase in birth rates and economic growth that can be observed after many catastrophes happen only if the climate allows it. Growth is the default human behaviour, like all life.
While it is true that modern society has a great capacity for sucessful adaptation, planetary climate change is something new. Not new to the planet, not even new to humans, but new to modern society. New problems might not have easy solutions or solutions at all.
Even if the problems of adaptation can be solved economicaly and without decreasing the birth rate, adapting has a cost. Using human tools we can reduce the cost and maximize gains if adaptation but there is always a cost.
Even if we had the will to face climate change with human tools (knowledge, science, engineering) there will be losses during the process of adaptation, but given the fact that humanity have decided to face climate change like animals, ignoring the long term danger, there is likely to be significant losses. After each one there is a posibility of war and collapse.