The article offhand mentions that we're on track for RCP 8.5, or 8.5 W/m^2 additional heat in 2100. That should
fucking terrify you. That's 4 C global temperature rise, a .75 meter sea level rise, and a doubling of ocean acidity. Page 82 of the IPCC report[1] has some fast facts- at RCP 8.5 most of the wild animals on earth will start dying out from lack of freshwater. Corals and molluscs will die out, and all ocean species will be affected. All coastal settlements will need extensive protection from higher sea level, and some will just be overwhelmed by the ocean. By 2300 they will all be overwhelmed by rising sea levels. Human food supply is greatly affected in the next 20+ years under RCP 8.5:
> All aspects of food security are potentially affected by climate change, including food production, access, use and price stability (high confidence). For wheat, rice and maize in tropical and temperate regions, climate change without adaptation is projected to negatively impact production at local temperature increases of 2°C or more above late 20th century levels, although individual locations may benefit (medium confidence). Projected impacts vary across crops and regions and adaptation scenarios, with about 10% of projections for the 2030–2049 period showing yield gains of more than 10%, and about 10% of projections showing yield losses of more than 25%, compared with the late 20th century. Global temperature increases of ~4°C or more above late 20th century levels, combined with increasing food demand, would pose large risks to food security, both globally and
regionally (high confidence)
The accompanying chart shows that human food yield is expected to decrease by ~25%.
> By 2100 for RCP8.5, the combination of high temperature
and humidity in some areas for parts of the year is expected to compromise common human activities, including growing food and working outdoors (high confidence).
What the report doesn't talk about is that by 2200, global temperature rise would be 6 C. 8 C by 2300. Those are both apocalyptic. The earth has only been that hot once before[2], and the warming period occurred over 20,000 years, caused by CO2 being released 20 times more slowly than we add it. Unlike the Paleocene-Eocene thermal maximum, species would not be able to adapt to this change. The mass die-offs would wipe out everything but the most resilient and isolated disaster species, and the Earth would enter an anoxic event. Methane and levels of other toxic gases would skyrocket and oxygen levels would suddenly plummet. Humans would need sealed shelters to survive. There would be no natural ice anywhere on earth.
Any worse than RCP 8.5 and the earth enters a runaway greenhouse. At that point the atmosphere turns into Venus, and life on Earth really would be over.
[1]: https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINA...
[2]: https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Therm...