In a world with such high climate sensitivity, is there still a realistic pathway to an acceptable outcome? SSP1 2.6 was already highly optimistic and with these two new models even it doesn't keep us below 2 degrees.
Maybe I am misunderstanding your statement, but to which period of time are you referring to? Your lifetime? 3 generations?
The long now includes a non-zero probability of a collapse of atmospheric oxygen, and complete human extinction within ~3600 years. [0]
We haven’t had a hypoxic atmosphere in the history of the earth since the evolution of photosynthesis (that’s a 2 Billion Year track record). The support for the plausibility of the author's hypothesis is that if you fit a parabola to the data over a certain time window, you get 100% decrease in atmospheric oxygen in a few thousand years??
That model is just nuts. By the same token it predicts we will have negative oxygen shortly thereafter.
However, you said:
> We haven’t had a hypoxic atmosphere in the history of the earth since the evolution of photosynthesis (that’s a 2 Billion Year track record).
This research seems to disagree, doesn't it? [0]
> Climate change triggered by volcanic greenhouse gases is hypothesized to have caused the largest mass extinction in Earth’s history at the end of the Permian Period (~252 million years ago). Geochemical evidence provides strong support for rapid global warming and accompanying ocean oxygen (O2) loss, but a quantitative link among climate, species’ traits, and extinction is lacking. To test whether warming and O2 loss can mechanistically account for the marine mass extinction, we combined climate model simulations with an established ecophysiological framework to predict the biogeographic patterns and severity of extinction. Those predictions were confirmed by a spatially explicit analysis of the marine fossil record.
[0] https://science.sciencemag.org/content/362/6419/eaat1327
[0]https://www.pnas.org/content/pnas/96/20/10955/F2.large.jpg
[1]https://en.wikipedia.org/wiki/Anoxic_event#Anoxic_events_in_...
It may be fit with a line+trigonometric to get some approximation for the next few years (10? 100?). With a line you get 50000 years to the 0 oxygen level, that is less alarmist than 3600 years.
Also, without a good model it's a bad idea to extend these projections too much. There are a lot of natural process that depend on the concentration of oxygen and will change. For example, under 15%-10% concentration of oxygen you can't burn wood so you solve the problem of forest fires https://en.wikipedia.org/wiki/Limiting_oxygen_concentration