Guest Post by Willis Eschenbach, title from a Paula Abdul quote
The backstory for today’s adventure is that this is the first scientific question I seriously researched. It is also the reason I don’t trust the “experts” or the “consensus”. In 1988, E. O. Wilson, an ant expert with little knowledge of extinction, made a startling claim that extinction rates were through the roof. He claimed there was a “Sixth Wave” of extinctions going on, and that we were losing a huge amount, 2.7% of all the species per year. This claim quickly went viral and soon was believed by everyone. So back in 2003, a decade ago now, I researched the question, found that Wilson was wrong by orders of magnitude, wrote it up, sent it around to the journals to see if they would publish it, and … well, let me just say that I was not received kindly. I was a voice crying in the wilderness. They didn’t give me a look-in, I was challenging the consensus. As far as I know, I was the only one saying that Emperor Wilson had no clothes … and as a result, I was not encouraged to continue publicizing my views.
But the world goes on, and three years ago I simplified and streamlined my work and published it as a post on WUWT entitled “Where Are The Corpses“. In it, I argued that there was no “Sixth Wave” of extinctions, that Wilson’s numbers were wildly exaggerated, and that current extinction rates (except in isolated islands and Australia) are not unusual in any way. Dr. Craig Loehle rewrote and developed the ideas, and he got it peer-reviewed and published in Diversity and Distributions, available here. Craig wrote about it in a post entitled “New paper from Loehle & Eschenbach shows extinction data has been wrongly blamed on climate change due to island species sensitivity“. Title says it all …
Figure 1. Stacked graph of total historical bird and mammal extinctions by year. This charts of the spread of European species (foxes, cats, rabbits, dogs, humans, weeds, diseases, etc.) to Australia and the islands. The earliest extinctions are from the time Europeans arrived in the Caribbean. There is a second wave of exploration and settlement in the 1700s. Finally, the spread of empires in the 1800’s led to the peak rates around the turn of the last century. Since then, the rates have dropped.
Having written so early and so extensively to try to debunk the claims of massive extinction rates and the bogus “sixth wave of extinction” hyped by the alarmists, I was pleased to receive a note from Anthony pointing out the publication of a new study in Science magazine (paywalled, naturally) entitled Can We Name Earth’s Species Before They Go Extinct? It’s gotten lots of media attention, mostly due to the fact that in the Abstract, they say that estimates of extinction rates are way overblown. My emphasis:
Some people despair that most species will go extinct before they are discovered. However, such worries result from overestimates of how many species may exist, beliefs that the expertise to describe species is decreasing, and alarmist estimates of extinction rates.
I must say, seeing that phrase “alarmist estimates of extinction rates” in Science made me smile, it was a huge vindication. However, I fear that they still have not grasped the nettle. I say that because at the end of the paper they say:
The estimates of how many species are on Earth (5 ± 3 million) are now more accurate than the moderate predictions of extinction rates (0.01 to 1% per decade). The latter suggest 500 to 50,000 extinctions per decade if there are 5 million species on Earth.
Why do I think that their conclusion is so badly flawed?
Like many modern scientists, rather than trying to find the most probable, they simply assume the worst. So they give their calculations assuming a 1% decadal extinction rate. Here’s the problem. That’s no more believable than Wilson’s 2.7% per decade rate. There are about 3,300 mammal species living on the continents (excluding Australia). If we assume that one percent of them go extinct per decade, that would mean that we should be seeing about 33 continental mammal extinctions per decade. It’s worse for birds, a 1% extinction rate for birds would be about 80 continental birds per decade. We have seen absolutely nothing even vaguely resembling that. That’s only slightly below Wilson’s estimate of a 2.7% extinction rate, and is still ridiculously high.
Instead of 33 mammals and 80 birds going extinct on the continents per decade, in the last 500 years on the great continental landmasses of the world, we’ve only seen three mammals and six birds go extinct. Only nine continental mammal and bird species are known to have gone extinct in 500 years. Three mammals and six birds in 500 years, that’s less than one continental mammal extinction per century, and these highly scientific folks are claiming that 30 mammals and 80 birds are going extinct per decade? … once again I’m forced to ask, where are the corpses?
This kind of world-blindness astounds me. I’ve heard of living in an ivory tower, but if you were making the claim that it’s raining, wouldn’t you at least look out the ivory windows to see if water were actually falling from the sky? How can you seriously claim that we’re losing dozens and dozens of species per year when there is absolutely no sign of that in the records?
Because the reality is that despite humans cutting down the forests of the world at a rate of knots for hundreds and hundreds of years, despite clearcutting for lumber, despite slash-and-burn, despite conversions to cropland, despite building hundreds of thousands of miles of roads and fences, despite everything … only nine continental mammal and bird species have gone extinct.
That gives us actual, not theoretical but actual, estimates of the historical extinction rates for continental birds and animals. For continental mammals that works out to 3 extinctions per 3,300 continental mammal species per 50 decades equals 0.002% per decade, somewhat below their low estimate of 0.01% per decade. For birds, it’s 6 extinctions per 8000 continental species per 50 decades, which is only slightly lower. If we assume that we’ve missed four out of five of the historical extinctions, very unlikely but I suppose possible, it still works out to only about 0.01%.
So their very lowest estimate, that of an extinction rate of 0.01% per decade, turns out to be a maximum estimate of what we’ve seen on the continents over the last five centuries.
Now, this does not include the islands and Australia. Rates there have historically been quite high. But the high historical rates there, as shown above in Figure 1, are the result of what might be called “First Contact”—the first introduction of numbers of European plants, animals, and diseases to previously isolated areas. But in 2013, there are few islands on the planet that haven’t seen First Contact. As a result, the extinction rates on the islands and in Australia, while still higher than on the continents, are extremely unlikely to have another peak such as they had at First Contact.
Finally, let me say that the low extinction rates should not be any cause for complacency. What my studies have shown is that the real threat to mammal and bird species is not habitat reduction, as incorrectly claimed for the last couple decades. The real extinction threat to birds and mammals is now and always has been predation, either by humans, or by imported “alien” species, particularly on islands. Hunting by humans threatens bonobo chimpanzees and other primates, as well as tigers, rhinoceros, and other mammal and bird species. Hunting is the extinction threat, not habitat destruction, and always has been, whether the hunters were animals or humans.
People are always giving me grief about how I’m not getting with the picture, I’m not following the herd, I’m not kowtowing to the consensus. I have no problem doing that, particularly given my experience regarding extinctions. For years I was the only person I knew of who was making the claim that E. O. Wilson should have stuck to his ants and left extinctions alone. Wherever I looked scientists disagreed with my findings. I didn’t have one person I knew, or one person I read, who thought I was right. Heck, even now, a decade later, the nettle still hasn’t been grasped, people are just beginning to realize that they were fools to blindly believe Wilson, and to try to manage a graceful climb down from the positions they took.
What I learned in that episode was that my bad number detector works quite well, that I should stick to my guns if I think I’m right, and that I should never, ever, ever place any faith in the opinions of the experts. They were all wrong, every single last swingin’ Richard of them, and I was right. Doesn’t mean I’ll be right next time, I’ve been wrong plenty both before and since … but it has given me the courage to hold on to some extremely minority positions.
It is my strong belief that I will also be vindicated in my claim that the earth’s temperature is regulated, not by CO2, but by a host of interlocking and mutually supportive homeostatic mechanisms that maintain the temperature within a fairly narrow range … time will tell. In my opinion, the experts in the climate field have shown that they don’t know a whole lot more about the real underpinnings of the climate than E. O. Wilson knew about extinctions … but that’s just me, and YMMV.
The very finest of a lovely day to you all,