If we see a heatwave like in Ministry for the Future where several hundred thousand people on a single city die from heat, does that count? It's catastrophic but not global? What if it happens in two unrelated places within a year? How about three?

"A global catastrophic risk is an event that has the potential to cause harm, death, and damage on an enormous scale". We're talking about millions of victims across multiple countries

I'm not sure climate change will ever qualify for a single event unless we count climate change as a single, ongoing event

If we apply that standard uniformly, then diarrhea has been a huge "global catastrophe" already, and yet no one spray-painted Stonehenge over it.

It follows from the commonly understood definitions of "catastrophe" that it refers to a sudden or somewhat stricly time-constrained event.

Apropos: https://x.com/AlexEpstein/status/1805949669412855983

Climate change would lead to a rise in temperature, one that would lead to droughts or even one that could make crops almost impossible to grow, leading to millions of casualties

But that would be a series of events that have a diffuser common cause, but are separate in time and space

That has been predicted over and over, for decades now, and all we see is improvements in crop yields and reduced mortality from just about every cause, including famine and moderate and extreme weather events.

What are the resolution criteria?

what does major economic collapse mean? I would argue it has happened already

Major economic collapse would be something similar to the great depression, the credit crisis of 1772, or the 2008 financial crisis.