They're also very likely underestimating or only looking at a fairly short time window. Worse yet, climate change and its results are only effects of a still deeper cause: using a very temporary surplus of non-replaceable resources, we overshot the planet's ability to indefinitely support human life, culture, economy, technology, everything human -- by nearly an order of magnitude. As we continue to refuse to reduce unsustainable rates of non-renewable resource consumption, we will cross scarcity thresholds that are expected to result in about 90 percent (or more) population attrition; not in a short time but still within just a couple of generations. It's nearly impossible to imagine any economy beyond very local economies surviving the transition.
Edited to add:
It's unfortunate that the vast majority of coverage of our modern predicament in widespread sources of news and commentary focuses only on the climate change part of the situation. Because that strongly implies to most people that there could be solutions which would avert or greatly mitigate the coming (and ongoing) disaster, if only we can reduce or even reverse human contribution to climate change quickly enough. But in fact that is a luxury we do not have, not even nearly. We are so far into overshoot that nothing we can do -- even if everyone were on board and like-minded -- can now prevent the attrition that lies ahead, coming at us through any combination of low birth rates, starvation, war, disease, weather events and 'disasters', and failure of infrastructure including health care.
For those who believe it's as simple as accomplishing a green energy transition, there's ample information online from reputable sources that explains how we don't actually have that outlet, as much as we certainly wish we did. The current population is essentially 90 percent made out of and enabled by cheap fossil fuels in ways that go far beyond just energy. Even waking up tomorrow with a perfect solution to fusion energy would not save us from the coming nitrogen shortage and a long list of other irreplaceable current materials and practices.