The tipping point is Lucy's World, when a particular straw finally breaks the monkey's back. In that scenario, it was plague that broke out of control when the country and planets civilised infrastructure was already under excessive stress from the cumulative effects of climate change.
The tipping point is essentially when you get enough of a mass die-off that infrastructure that moves goods and services no longer functions, and Humanity's population takes a nose dive from it's 10 billion to a few million. At that point we're living in Mad Max's world, with very little possibility of us bootstraping back up, and the very heavy likelihood that we would lose our cumulative technological, social, and artistic legacies within a generation.
A few centuries after we've been knocked back to subsistence farming, the atmosphere should be cleaning itself out. But having exhausted all the easy to obtain fossil fuels, we would never recover our civilization again.
Different tipping point.Actual climate tipping points are what he's talking about. The climate shifting into a different stable mode where even stopping human carbon emissions and waiting centuries won't get us back to where we were.