Yeah, I wonder: at what rate do species go extinct without human intervention? Like, if we were responsible for 90% of extinctions or 10% of extinctions, that seems a pretty important distinction. Also, the ratio of “human-caused” to “non-human-caused” extinctions seems like it has the advantage that (I would expect) it would obviate concerns about what counts as different species or not: if one researcher draws the line more finely than another, and hence thinks there are 10x as many species as the other, I expect they’ll produce estimates of ~10x for both the numerator and the denominator, which will cancel out.
There is a lot of work on this under the title “background extinction rate”—see https://www.nature.com/articles/nature09678 for a review. Estimates for the current extinction rate (measured in extinctions/million species years) can be anywhere from 10-1000x faster than the background extinction rate, but it depends a lot on the technique used and the time interval measured. EDIT: typo in numbers
You probably also have to estimate some sort of “no human take off” counterfactual extinction rate and compare them to get the upper bound.
Yeah, I wonder: at what rate do species go extinct without human intervention? Like, if we were responsible for 90% of extinctions or 10% of extinctions, that seems a pretty important distinction. Also, the ratio of “human-caused” to “non-human-caused” extinctions seems like it has the advantage that (I would expect) it would obviate concerns about what counts as different species or not: if one researcher draws the line more finely than another, and hence thinks there are 10x as many species as the other, I expect they’ll produce estimates of ~10x for both the numerator and the denominator, which will cancel out.
There is a lot of work on this under the title “background extinction rate”—see https://www.nature.com/articles/nature09678 for a review. Estimates for the current extinction rate (measured in extinctions/million species years) can be anywhere from 10-1000x faster than the background extinction rate, but it depends a lot on the technique used and the time interval measured. EDIT: typo in numbers