E pur si muove

Guest Post by Willis Eschenbach

A few years back, some scientists got together and invented something they call the Living Planet Index, or LPI. It’s supposed to measure how well (or poorly) the species that make up the living world are doing. They say it is a “measure of the state of the world’s biological diversity based on population trends of vertebrate species.” So it’s an index based on the decline of some selected species, which is claimed to represent the decline of the species of the “living world”.

Here’s the big news from their latest report.

The Living Planet Index claims an average 70% decline in the populations of species worldwide since 1970.

YIKES! 70% loss since 1970! EVERYONE PANIC!

But is this true?

Over in the Twitterverse where I’m @weschenbach, I said that based solely on my experience, their claim was nonsense. I’ve spent a lot of the last half-century outdoors in the elements, both on land and on and under the sea, around the planet. I said I would have noticed a 70% reduction in species populations.

Of course, folks who spend their lives behind desks in a city thought I was being ridiculous, and they laughed uproariously. How could I be so certain? Plus of course, there were the claims of “But Willis, those are actual scientists! How can you doubt them?”

So I thought I’d take a look at some real data. Let’s get a sense of the number of the species involved.

There are estimated to be around 8.7 million species on earth. Of these, about 65,000 are vertebrates.

How many of these 8.7 million species are studied by the Living Planet Index? Well, not all of them.

First, no plants, no fungi, no chromista. Next, only vertebrates, and only some of those, specifically fish, mammals, birds, reptiles, and amphibians.

The good news is that the IUCN Red List of Threatened Species, which is the official keeper of data on which species are threatened or not, lists data for 62,493 vertebrates, so it covers pretty much all of the vertebrates.

It also allows us to search based on various criteria, including those used by the LPI listed above.

And when we eliminate the vertebrate species the LPI doesn’t include, we end up with 59,866 species fitting the LPI criteria—mammals, birds, reptiles, fish, and amphibians. Of course, they didn’t look at all of them, only 5,230. But I wanted a larger view of the issues.

The Red List also lets us see if the populations of each species are increasing, stable, or decreasing.

Of the populations of the 30,763 of the LPI-studied mammal etc. species for which the Red List has population data, 53% have stable or increasing populations. So we’re left with 14,565 species with decreasing populations. Call it half to be generous.

Here’s the problem. If around half the species for which we have data are stable or increasing, then even if the rest were all totally extinct, the average decline would only be 50% … far from the 70% they claim.

Oooops …

Next, as a sensitivity analysis, let’s assume every one of the 28,714 species for which we don’t have the population trend is decreasing. Clearly, that’s not possible—some will be increasing or stable. And because the Red List is focused on threatened species, the unknown species will likely be weighted towards stable species. But it’s a sensitivity analysis, so we’ll assume every one of the unmeasured species is decreasing.

With that impossible assumption purely for a sensitivity analysis, it would mean only 27% of the species are stable or increasing.

And the problem still remains. With 27% not decreasing, the only way to get to a 70% decrease in population is if almost every one of the 33,861 theoretically decreasing species is already extinct or on the brink of extinction. Only that impossible situation would give us a 70% average decrease.

Conclusions?

Out of 59,866 species fitting the LPI criteria for which we have population data, just over half are stable or increasing.

Of the 59,866 species, only 8,509 are both decreasing and in some trouble (vulnerable or near threatened or endangered or critically endangered). Here’s the Red List Report:

The endangered and decreasing fish, birds, reptiles, amphibians, and mammals are 0.001% of all species, and there’s no reason to assume that their condition reflects the world situation.

The 70% claim of the LPI is falsified by the Red List data.

As I said, I have investigated this because based solely on my experience, I said I didn’t believe the LPI numbers, and folks laughed at that. And now, having studied the species data, I find that my experience is correct—their claims don’t hold water.

So how did the scientists behind the LPI get it so wrong? Obviously, their selected species are not representative of the whole.

I would suggest that Upton Sinclair had the answer to that. He said:

“It is difficult to get a man to understand something, when his salary depends on his not understanding it.”

The problem is, if the LPI was going up, or just slightly downwards, the scientists behind the LPI would be out of a job. To use George Orwell’s term, that’s doubleplusungood …

And almost inevitably, this leads to an unconscious bias in their choice of species, locations, and studies to include in the LPI. For the LPI, they’ve studied 31,821 populations of 5,230 species. So no overt bias is needed—just picking study A over study B because reasons, choosing population 1 over population 2, selecting species Alpha over species Beta, lather, rinse, repeat, and soon you have a 70% decline since 1970.

Finally, please be clear that I’m not saying that we should ignore population decreases. I’ve been a commercial fisherman for a good deal of my life, and I’d like my grandson to be able to do the same. The only way for that to happen is for us to care for the other life forms with which we share this magical planet. I’m just saying that the LPI is just more unsupported alarmism.

Best to all, and yeah, I’ll continue to trust my experience despite people laughing at it … I’m funny that way.

w.