Sixth Extinction

Geological eras are marked by mass extinction events.  In an article for Science, lead author Rodolfo Dirzo of Stanford University says we are beginning the sixth such event he refers to as "Anthropocene defaunation".

Update (September 9):  Further evidence for a mass extinction.  And especially bad news for birds.

Update (November 30):  An interview with Sean Carroll who hosts a documentary about mass extinction.

Update (December 17):  Will humans go extinct?  Well, we're working on it.  Something like climate change denial is tied up with several aspects of our psychology.  We're very smart--but just not quite smart enough.

Update (January 6, 2015):  I can joke with a colleague about how human extinction would cut into my retirement plans.  But underneath, a deep, deep sadness.

Update (April 30, 2015):  A metastudy published in Science finds that up to one-sixth of all species could go extinct due to climate change.

Update (May 4, 2015):  Sixty percent of large herbivores face extinction. These reports always bother me more than our own impending doom because, of course, these animals have no control over their fate.

Update (June 1, 2015):  Joe Romm doesn't think we'll go extinct, but overshooting our population limits is a problem.

Update (June 20, 2015):  A study published in Science Advances concludes that vertebrates are going extinct at a rate 114 times faster than the background rate.

These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.

Update (June 22, 2015):  Lindsay Abrams makes note of a quote from the lead author of the Science Advances study, Gerardo Ceballos:

If [this rate of extinction] is allowed to continue, life would take many millions of years to recover, and our species itself would likely disappear early on.

Update (June 24, 2015):  Maybe it will be food shortages that do us in.

Update (July 7, 2015):  An interview with Guy McPherson, co-author of Extinction Dialogs.  He makes the point that economic collapse itself can add to warming when the production of sulfates ends.  Makes the events in China and Greece a little more ominous.

Update (July 11, 2015):  Interviews with Jason Box and other climate scientists -- "When the End of Human Civilization Is Your Day Job".

Update (August 3, 2015):  A study by the Global Sustainability Institute at Anglia Ruskin University forecasts a social collapse due to food shortages under "business as usual" scenarios.

Update (August 11, 2015):  A study published in Conservation Biology claims that invertebrate extinction has been underestimated.

Update (January 9, 2016):  An article in Science supports the contention that the current epoch should be recognized as the Anthropocene.

Update (January 24, 2016):  Phil Torres says that the loss of biodiversity is an under-reported problem.

Update (September 3, 2016):  The Working Group on the Anthropocene has voted to recommend designating the period starting in 1950 as the Anthropocene epoch.

Update (July 16, 2017):  A study published in Proceedings of the National Academy of Sciences finds large declines in range and population even among species not considered endangered.

Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a “biological annihilation” to highlight the current magnitude of Earth’s ongoing sixth major extinction event.

Update (August 13, 2017):  The Ends of the World by Peter Brannen looks at the five major mass extinctions in earth's history. Biology itself has had a role (the production of oxygen), but largely the cause has been carbon dioxide outgassing which lead to temperature rises (even the famous impact from 65 million years ago likely triggered massive volcanic eruptions that caused most of the damage).

And while humans are tied to many extinctions already, the overall impact has been about one percent of species compared to 70 to 95 percent in previous episodes. So, it's not a "mass" extinction--yet. Paleontologist Doug Erwin is quoted:

[I]f it's actually true we're in a sixth mass extinction, then there's no point in conservation biology.

Erwin says that a network collapse can't be stopped which means we could be early enough in the process to really do something about it. But this bit of optimism must be tempered by the fact that the system is non-linear.

[E]verything's fine until it's not. And then everything goes to hell.

The only hope we have in the future is if we're not in a mass extinction event. 

Update (September 18, 2017):  Animal agriculture is a leading cause of wildlife extinction.

Forests that are home to endangered animals like the Sumatran elephant are being cleared to grow feed crops for cows, pigs and chickens at factory farms. Fish like anchovies and sardines are being caught in alarming quantities to be made into feed for farmed salmon, pigs and chickens. This means that penguins and other animals who naturally feed on these fish now face a grave situation.

Furthermore, animal agriculture produces more greenhouse gas emissions than all the cars, planes, and other forms of transportation combined, exacerbating the perilous effects of climate change.

Update (December 16, 2017):  An asteroid had a near miss with Earth (6.2 million miles) and has the potential to eventually hit the surface. But I think Keith Spencer doesn't reflect Peter Brannen's account of recent understanding (emphasis added).

Major extinction events on Earth, generally caused by asteroid impacts, are believed to happen at least once every hundred million years, and perhaps more frequently.

Update (December 24, 2017):  Matthew Rozsa contemplates our extinction.

How we wind up dying off collectively matters a great deal in terms of how we can cope with the underlying meaning of the very fact that we existed at all. There is no shame in dying off because of some event that was entirely beyond our control, like an asteroid hitting earth, or even one that we caused for understandable reasons, like fighting diseases so effectively that they evolved into superbugs. On the other hand, it will be shameful if we die off because a faction of our population was unwilling to restrain polluters who caused unnecessary climate change. There are other ways in which pollution could kill us off (look at the declining bee populations, for one thing), and beyond that there is always the possibility that nuclear war could do us in. If the unrestrained ids of fanatics or fragile egos of powerful men wind up resulting in our annihilation, it would be hard to imagine how we could explain ourselves to any hypothetical god.

Update (July 24, 2019):  Rowan Jacobsen reports on findings that wild bees are more productive than domesticated honeybees.

As we enter an era of dire food insecurity, one of the easiest things we can do to ensure the global food supply is to enhance populations of wild pollinators. Unfortunately, we seem to be doing just the opposite.

But wild bee populations are declining as well in part due to diseases spread by hauling honeybees around the country.

Update (October 3, 2021):  23 species are being listed as extinct.