The word catastrophic is hard to quantify, so it is not a scientific word, it is a matter of how effects apply in different situations.
For example, when a small ‘climate event’ happened in 1783, it had effects that some would describe as catastrophic..
A similar event a few decades later also had profound effects …….
And the Russian heatwave in 2010 had effects that certainly have led to consequences..
These are tiny compared to what will come.