Mass Extinction, Past and Present

Scientists have uncovered another ancient mass extinction. Find out what we can learn from this event for our own time.

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Growing up around here, one of the standard field trips for kids was a trip to the Royal Ontario Museum (ROM).  It’s a stately Edwardian building in Toronto, built in a neoclassical style.  When I was growing up, it was the quintessential traditional museum, along the lines of the British Museum in London or the American Museum of Natural History in New York.  It’s the oldest and the biggest museum in Canada.

We liked the suits of armor and the artifacts from the First Nations, but the star attraction was always the dinosaurs.  The Barosaurus was awe-inspiring for a child.  At 27 metres long, it’s the largest mounted, real fossil dinosaur skeleton in Canada, and one of only three complete Barosaurus skeletons on display in the world. It’s one specimen in an impressive gallery that presents one of the largest dinosaur collections on earth.

The question that arises, in young minds and old, is, “how could such powerful and plentiful creatures vanish?”  It’s not only the dinosaurs.  Biologists have discovered that more than 99% of species have gone extinct. Sometimes it’s an isolated event and sometimes it’s part of a global disaster.  This type of disaster is called a mass extinction or a biotic crisis.

We’ve known about five mass extinctions

We’ve known about five mass extinctions for a while now.  They’re called the End Ordovician, 444 million years ago, the Late Devonian, 375 million years ago, the End Permian, 251 million years ago, the End Triassic, 200 million years ago, and the End Cretaceous, 66 million years ago.  All five of these events have something in common.  They resulted from giant eruptions that covered wide areas of land or the ocean floor with the mineral basalt.

This week, we found out about another ancient mass extinction, thanks to a new analysis published in the journal Historical Biology.  A team of researchers from NYU have concluded that an additional biotic crisis took place during the Guadalupian, or Middle Permian period, 272 to about 260 million years ago.  “In terms of both losses in the number of species and overall ecological damage, the end-Guadalupian event now ranks as a major mass extinction, similar to the other five,” the authors tell us.

This newly discovered crisis happened at the time of the Emeishan flood-basalt eruption.  That eruption created an extensive rock formation in southern China.  The Emeishan event was as large as the others noted above.  The lead researcher, Professor Michael Rampino explains, “Massive eruptions such as this one release large amounts of greenhouse gases, specifically carbon dioxide and methane, that cause severe global warming, with warm, oxygen-poor oceans that are not conducive to marine life.”

there have actually been six mass extinctions

This means that, instead of the traditional five mass extinctions, there have actually been six.  We should note that these past events have all involved greenhouse gases and global warming.  Ecologists are telling us that we are now in the middle of a new mass extinction.  The difference is that this one hasn’t been caused by flood-basalt eruptions.  It’s caused by human activity.

They are calling this new crisis the Holocene or Anthropocene.  It has five causes; land and sea use, direct exploitation of organisms, climate change, pollution and invasive alien species.  Over a million animal and plant species are facing extinction all at once. That is more than ever before in human history.   Our species is the cause and only our species has the capacity to prevent and reverse it.

The researchers are hoping that their findings can help us to better understand mass extinctions, including the one we face today.  As Professor Rampino put it, “it is crucial that we know the number of severe mass extinctions and their timing in order to investigate their causes.”

our current mass extinction is from human activity

As we said, like climate change, our current mass extinction results from human activity. It comes from demographic and economic drivers of change. These drivers include population growth, mass consumption, new technology and weak governance. Typically, we extract and produce resources in one part of the world to meet the needs of people on the other side of it. This has led to global inequities.

Human activity has changed 75% of our land mass and 66% of our oceans. Over a third of our land surface and 75% of our freshwater now goes to agriculture. We have tripled our agricultural production since 1970, raised timber production by 45%, and we consume double the renewable resources we did in 1980. We catch 33% of our fish stocks beyond what’s sustainable, and we have maxed out another 60%. Our urban areas have doubled, and we have increased plastic pollution tenfold since 1980.

By studying mass extinctions from the past, we can learn about both their cause and their prevention.  This can help us with our current species extinction emergency.

We always have more to learn if we dare to know.

Learn more:

NYU
The end-Guadalupian (259.8 Ma) biodiversity crisis: the sixth major mass extinction?

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