June 07 , 2019
Fears of a Sixth Extinction
The UN recently released a report that claims human activity is putting at risk a million species for extinction. This would be a catastrophic blow to our natural environment and has made many observers sit up and take notice. The destruction of that many species would in fact be a “sixth extinction”.
While species come and go all the time at a very low rate, in Earth’s history, the fossil record shows that there were five major “mass extinction” events. The best known was 66 million years ago, at the end of the Cretaceous, when a massive asteroid hit the Earth in the Gulf of Mexico, and caused the dinosaurs to die out, clearing a path for mammals to take over the Earth. The biggest mass extinction event actually occurred 250 million years ago, when all the continents on Earth came together to form a single landmass called Pangea. The time was associated with major climate change and volcanic activity that poisoned the oceans with hydrogen sulfide gas. We are in fact nowhere near another mass extinction similar to those events.
In mass extinctions, 20% or more of all species die out. To be more specific, 20% of complex animal and plant life die out. Bacteria, which actually make up most of the species on Earth, are not really counted in all this. The UN Report on this question is actually deceptive. To make a decent attempt to count how many species will go extinct, we must first know how many species there are. Scientists have identified and named about 1.5 million complex animal and plant species. When it comes to the best-known animals, the birds and mammals and reptiles and fishes, we have a range of about 6,000 mammals to about 35,000 fish. But the UN study did not start with this number, instead they assumed that we have not found most of the life on Earth and that there are really 10 million species. That cannot be taken seriously. Where are these other 8.5 million species hiding? Biologists are all over the Earth, and much of North America, Europe, China, and Japan along with other areas are well-explored so how can so many species be missing? Are they all miniscule insects? It is inconceivable that thousands of mammals and birds and fishes remain totally unknown to us, much less millions.
The second error the UN makes is their method for predicting extinctions. They took a survey of about 100,000 species done by the International Union for the Conservation of Nature (IUCN) which is the main body that maintains the list of endangered species. In this survey the IUCN found that about 25% of the species were under some level of pressure that put them at potential risk of extinction at some point in the future (decades to centuries from now). The UN then applied that 25% figure to their estimate of 10 million species, but to be conservative just cut that down to 10%, and declared that to be the correct number.
This is sloppy methodology. The actual data shows that only about 500 species have gone extinct since 1900, with the last few decades seeing very few extinctions. There is no mass extinction now or imminent in the future. This issue is being extremely exaggerated, mainly to panic the public into action.
There is a kernel of truth in the fearmongering. Human activity has taken over vast tracts of land for agriculture and grazing and has overfished the oceans. This pressure has led to a marked decline of available habitat for many species. Lions used to roam all of Africa and the Middle East and are now living in smaller isolated regions. Same is true for tigers in South and East Asia. Humans have also deliberately hunted some animals to the brink of extinction including whales, elephants, and rhinos. The passenger pigeon was hunted to extinction one hundred years ago, and bison almost disappeared from North America.
The good news though is that all these pressures are coming to an end. Whaling has been essentially banned for decades. In North America bison, wolves, grizzly bears, mountain lions, and bald eagles are all expanding. The trade in elephant ivory and tiger parts, driven by demand from East Asia, is being curtailed. More importantly, the world over, more and more land and ocean areas are being turned into protected zones. National Parks are expanding.
The biggest piece of good news is that more land is no longer being gobbled up for agriculture. Despite rising populations, increasing crop yields and better livestock management has meant that we have not needed to use more land for the last several decades. In the richest regions like North America and Europe farmland has been returning to wild with forests expanding rapidly. Forests are growing even faster in Russia which includes the northern half of Asia. China has spent 100 billion dollars on planting and expanding forests and has ambitious targets to expand forests to 26% of China by the next decade. The biggest gains will be in the next 80 years. As yields continue to grow 1-2% per year, and population growth slowing and stopping, even more farmland will go back to nature. By the end of this century, we may need only half as much land as currently used to grow all our food and livestock. The immense pressure that humanity exerted on nature in the last century was not a sign of worse to come. It was a peak from which we have started to retreat and will do so at an accelerating pace. There will be no sixth mass extinction.
