That sounds pretty extreme. I’d be Interested in reading that article, if you can find it.
https://www.ipcc.ch/report/ar6/syr/
I’m looking at the Full Volume, and on page 71 you can see
With about 2°C warming, climate-related changes in food availability and diet quality are estimated to increase nutrition-related diseases and the number of undernourished people, affecting tens (under low vulnerability and low warming) to hundreds of millions of people (under high vulnerability and high warming) … Climate change risks to cities, settlements and key infrastructure will rise sharply in the mid and long term with further global warming, especially in places already exposed to high temperatures, along coastlines, or with high vulnerabilities (high confidence).
At global warming of 3°C, additional risks in many sectors and regions reach high or very high levels, implying widespread systemic impacts, irreversible change and many additional adaptation limits (see Section 3.2) (high confidence). For example, very high extinction risk for endemic species in biodiversity hotspots is projected to increase at least tenfold if warming rises from 1.5°C to 3°C (medium confidence). Projected increases in direct flood damages are higher by 1.4 to 2 times at 2°C and 2.5 to 3.9 times at 3°C
Global warming of 4°C and above is projected to lead to far-reaching impacts on natural and human systems (high confidence). Beyond 4°C of warming, projected impacts on natural systems include local extinction of ~50% of tropical marine species (medium confidence) and biome shifts across 35% of global land area (medium confidence). At this level of warming, approximately 10% of the global land area is projected to face both increasing high and decreasing low extreme streamflow, affecting, without additional adaptation, over 2.1 billion people (medium confidence) and about 4 billion people are projected to experience water scarcity (medium confidence). At 4°C of warming, the global burned area is projected to increase by 50 to 70% and the fire frequency by ~30% compared to today
However, if you really want to get into it, you can read the Climate Change 2022: Impacts, Adaptation and Vulnerability Full Report. It has a lot more details about the effects of climate change on all parts of the world, but it’s also a 3,000 page pdf.
It’s mild hyperbole, but it’s not far off from best-guess speculation. It’s well and regularly covered in IPCC reports. Have at.
