Wednesday, July 12, 2017

Sixth mass extinction likely underway with humans as the asteroid

I've mentioned the sixth mass extinction exactly once before in I missed World Giraffe Day on Sunday, when I wrote "Those numbers remind me that humans causing a sixth mass extinction has been in the news this week.  I'll get to that later."  That was more than two years ago.  That's a long time, even for me, to return to a promised topic of such importance.  Fortunately, Newsy reminded me this week when it asked Are we really in the 6th mass extinction?

Increased extinction rates and population losses might be signs of another mass extinction. But some researchers are doubtful.
The Proceedings of the National Academy of Sciences just published Ehrlich and others' Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines, which begins with this paragraph about the study's significance.*
The strong focus on species extinctions, a critical aspect of the contemporary pulse of biological extinction, leads to a common misimpression that Earth’s biota is not immediately threatened, just slowly entering an episode of major biodiversity loss. This view overlooks the current trends of population declines and extinctions. Using a sample of 27,600 terrestrial vertebrate species, and a more detailed analysis of 177 mammal species, we show the extremely high degree of population decay in vertebrates, even in common “species of low concern.” Dwindling population sizes and range shrinkages amount to a massive anthropogenic erosion of biodiversity and of the ecosystem services essential to civilization. This “biological annihilation” underlines the seriousness for humanity of Earth’s ongoing sixth mass extinction event.
Most species are not going extinct, not yet, but lots of their populations are going extinct.  That's a warning sign of worse to come, regardless of what the other scientists, who I think are being overcautious, say.

Ehrlich hasn't been the only one sounding the warning.  Follow over the jump for two videos featuring Elizabeth Kolbert, the author of "The Sixth Extinction," plus SciShow being perversely optimistic.

The most recent is The Sixth Extinction, a short infographic- and animation-rich clip from Fusion.

“This time, humans are the asteroid.” The New Yorker journalist Elizabeth Kolbert says we may be triggering a mass extinction on earth. Here’s why.
That was from this May.  Kolbert's book, which I own, came out three years ago.  Vox interviewed her then, asking Is another mass extinction on the horizon?

There have been five mass extinctions in Earth's history. Author Elizabeth Kolbert thinks we may be headed for another.
As I tell my students, in the short run, mass extinctions cause massive loss of diversity and ecosystem collapse.  In the long run, they open up opportunities for the survivors.  SciShow attempts to predict which animals those would be in Who Will Survive The 6th Mass Extinction?

Some scientists say we’re in the midst of Earth’s sixth mass-extinction event, caused entirely by us. But some animals have a knack for surviving in a human-dominated world. What’s their secret?
The prediction's right, as far as it goes, but it assumes either that humans will be able to survive and maintain urban environments in the face of ecosystem collapse or that the animals will survive the collapse of civilization after taking refuge in cities and then dispersing back into the wild when their competitors have become extinct.  That second one is the better assumption.

Oh, my.  When I promised something more serious today, I had no idea how serious!

*Paul Ehrlich became famous for his 1968 book, "The Population Bomb," in which he forecast 7 billion by 2005 (we got there in 2011) and mass famines killing hundreds of millions during the 1970s unless something was done to vastly increase food production, which did happen as Bloomberg noted two years ago.  Even though he ended up being wrong, at least about the 1970s (the 2020s and 2030s may be another story), his polemic alerted people to the problem and help push through a solution.  This Crazy Eddie approves.  May his current warnings do the same for biodiversity.

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