Could global warming lead to an oxygen shortage by 2100? [duplicate]

Question

In this report of a mathematical model (original paper here) about the response of ocean plankton to climate change, its author claims the following:

By 2100, the earth at sea level could have atmospheric oxygen levels comparable to the top of Mount Everest today. And as far as I know, people cannot normally stay on Everest without oxygen masks for more than a few minutes.

I'm not interested in whether his model about the oxygen production by plankton is correct or not, but is his claim that the consequence of this could be an immediate shortage of oxygen remotely credible? To put this another way, even if oxygen production in the ocean suffered a catastrophic decline, would we see oxygen shortages by 2100?

NB. This question was raised as the linked paper has now generated more than one question here (Will global warming reduce available oxygen? and Is space exploration even possible in an oxygen constrained Earth?). Neither of these question address the most outrageous claim in the news stories that global warming could lead to a ~70% reduction in the atmospheric oxygen by 2100 (the partial pressure of oxygen at the top of Everest is about 30% of its value at sea-level). One commenter on the original question even suggested that this, much more specific, question should be asked. So stop saying it is a duplicate: it is clearly a much more specific claim that is completely unaddressed in the answers to the other questions.

Answer 1

Disconnect between journal article and the blog post on it

The sketchy claim investigated in this question is:

“By 2100, the earth at sea level could have atmospheric oxygen levels comparable to the top of Mount Everest today. And as far as I know, people cannot normally stay on Everest without oxygen masks for more than a few minutes,” Petrovskii said.

While this quote is attributed to the author of the journal article, this claim doesn't appear in the journal. Rather:

Note that it was not our aim here to calculate precise critical values of the oxygen production rate. Instead, our aim is to identify the new threat in principle rather than to link our analysis to specific plankton species or specific marine ecosystems.

This stress on "in principle" seems to reflect that the authors didn't want to actually claim that they believed this to be a threat.

Additionally, the journal stresses that they were reporting a model without even attempting to estimate the values for the parameters:

Similarly, we do not attempt to estimate the value of the model parameters.

Finally, they note that this model wasn't an attempt at realism:

In contrast to other simulation studies where complicated “realistic” marine ecosystem models were used (e.g., Chapelle et al. 2000; Fasham et al. 1990; Hull et al. 2008), our model is relatively simple.

Checking Google, the earliest found reference to the alleged quote comes from "Report: The World Will Run out of Breathable Air Unless Carbon Is Cut" (2015-12-03). This story reports the quote in relation to the article, but since it's not in the article, it's unclear how the reporters obtained it; they don't mention an interview or correspondence with the author.

So:

• We're not sure if the journal article's author actually made this claim.

• Even if the claim's real, it doesn't appear to be peer-reviewed.

• The peer-reviewed journal article explicitly disclaims concrete claims and realism, stressing that they were only trying to demonstrate a concern "in principle".

• As noted by the estimates above, the claim seems pretty implausible.