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The World Wide Fund for Nature warns that

there is, in fact, a very serious biodiversity crisis.

And illustrates this with an unreferenced "scientific analysis"

These experts calculate that between 0.01 and 0.1% of all species will become extinct each year.

From this, they conclude that - depending on the estimate of how many species there are, up to 100,000 species are becoming extinct every year.

Are their uncited calculations accurate? Do experts think that the extinction rate is per annum is between 0.01% and 0.1%?

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    You are plowing into difficult questions about how to count species, as the article suggests. Could we change the question to be "Is the species extinction rate over 0.01% per year?" I think it still has the flavour of your question but might avoid debates about definitions of species.
    – Oddthinking ♦
    Commented Oct 26, 2017 at 14:38
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    @Oddthinking I don't really understand your point, but do as you feel best, we all want high-quality questions
    – BlueMoon93
    Commented Oct 26, 2017 at 14:51
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    Made a significant change to avoid us getting bogged down in how many species there are.
    – Oddthinking ♦
    Commented Oct 29, 2017 at 10:37

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776 species have gone extinct since year 1500 according to the most comprehensive global survey of threatened species, The IUCN Red List of Threatened Species. The number of species that go extinct without anyone noticing may probably be large, but not 10,000 times as high as the number of species confirmed by IUCN.

Figures like "10,000 and 100,000 species are becoming extinct each year" are fictitious numbers derived from mathematical models, not empirical science. Search google scholar for "Species–area relationship model" if you want find out howcome some environmentalist campaigners use numbers that are thousands of times higher than the numbers from biologist that actually try to count number of extinct species. (eg. Nature "Species-area relationships always overestimate extinction rates from habitat loss"

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    Your first paragraph answers the question and is well sourced. Your second paragraph makes a specific claim, but is very poorly sourced. The linked paper makes several statements about how much of an overestimate the mathematical models are; The highest stated number is 165%. Your second paragraph implies that there is some credible source that actually makes the 10,000 times number, when you show no evidence of that at all. Google scholar will show you scientific papers, not literature written by environmentalist campaigners. It sounds a lot like you are conflating the two.
    – BobTheAverage
    Commented Oct 29, 2017 at 2:26
  • "derived from mathematical models" - we have not got close to identifying every species - that goal probably doesn't even make sense. So, if we want to know how many species we are losing, we have to use mathematical models - they are the closet we can get to the truth. The 776 number is largely meaningless without models to understand it.
    – Oddthinking ♦
    Commented Oct 29, 2017 at 9:30
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    Ah, I actually had a look at the second paper. It doesn't match what you say it says. It isn't about "environmentalist campaigners", it doesn't suggest the errors are "thousands of times higher". It is actually all about tweaking the mathematical models that you deride. It suggests the errors from other scientists are between 15% and 160% too high. Worth fixing, sure, but hardly a destruction of the concept.
    – Oddthinking ♦
    Commented Oct 29, 2017 at 10:36
  • Could it be that tose "776 extinct species" are limited to certain typeg, e.g. mammals or vertebrate? Including insects the number would be astonishing low.
    – Sven
    Commented Oct 30, 2017 at 11:25
  • @ZsoltSzilagy Those 776 extinct species are limited to ones we have identified and confirmed as extinct. An unknown number of species have gone extinct without being described by a biologist. Another unknown number has gone extinct and no one noticed they were gone.
    – BobTheAverage
    Commented Oct 30, 2017 at 19:13

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