4 ms·
Anchoring against the cumulative number of species that have ever existed is a strange baseline, that's a metric that will emphasise "hey, life on earth is old"
by shoo 1y ago
Anchoring against the cumulative number of species that have ever existed is a strange baseline, that's a metric that will emphasise "hey, life on earth is old" but makes it very hard to say if there's anything unusual or not about the current period.
The more common baseline I've come across is comparing the estimated rate of species extinction from the last century or so versus the baseline historical extinction rate.
To pick an arbitrary article about extinction rates with citations to published research:
> But this estimated [background extinction] rate is highly uncertain, ranging between 0.1 and 2.0 extinctions per million species-years. Whether we are now indeed in a sixth mass extinction depends to some extent on the true value of this rate. Otherwise, it’s difficult to compare Earth’s situation today with the past.
> In contrast to the the Big Five [mass extinction events], today’s species losses are driven by a mix of direct and indirect human activities, such as the destruction and fragmentation of habitats, direct exploitation like fishing and hunting, chemical pollution, invasive species, and human-caused global warming.
> If we use the same approach to estimate today’s extinctions per million species-years, we come up with a rate that is between ten and 10,000 times higher than the background rate.
https://theconversation.com/what-is-a-mass-extinction-and-are-we-in-one-now-122535 https://theconversation.com/what-is-a-mass-extinction-and-ar...
- jrowen 1y agoThis is an interesting analysis, but it does feel a bit apples-to-oranges. It is good to seek perspective on the impact we are having, but in terms of "are we in an extinction event" it feels woefully premature to me, perhaps even comically futile. 1. For all of the others, we are piecing together bits of evidence spanning eons. Can we really compare estimated background extinction rates over hundreds of millions of years to the by-comparison hyper-detailed and extensive data we have from the last 100? 2. This time it's different. Humans are categorically different from past drivers of extinction. I don't think there is a whole lot to extrapolate from. We can selectively preserve species we care about. We can run roughshod over others without even noticing. The impacts of our actions on the global ecosystem, from construction to medicine to pollution to deforestation, are unique. We could hold in a relative stasis where biodiversity continues declining but at too slow of a rate to really be considered a mass extinction. Or we could blow it all up tomorrow. Or we could unlock bioengineering and see an explosion unlike any before. By the criteria in the article it could be millions of years before we can say anything conclusively.
- jrowen 1y agoUpon some further reading, particularly this[1] page, I'm going to revise this stance and say that the evidence and consensus is pretty substantial. I do still think "it's different" but even starting from the late Pleistocene it's pretty clear that we're highly disruptive. [1] https://en.wikipedia.org/wiki/Holocene_extinction https://en.wikipedia.org/wiki/Holocene_extinction