In The World’s ‘Sixth Extinction,’ Are People The Asteroid?

The dinosaurs have been killed through the Fifth Extinction — which scientists suspect was attributable to an asteroid. Now, we live via an epoch that many scientists describe because the Sixth Extinction, and this time, human exercise is the offender. As one scientist put it: We’re the asteroid.

Elizabeth Kolbert is the writer of the brand new guide The Sixth Extinction. It begins with a historical past of the “big five” extinctions of the previous, and goes on to elucidate how human habits is making a sixth one — together with our use of fossil fuels and the consequences of local weather change.

“We are effectively undoing the beauty and the variety and the richness of the world which has taken tens of millions of years to reach,” Kolbert tells Fresh Air‘s Terry Gross. ” … We’re sort of unraveling that. … We’re doing, it’s often said, a massive experiment on the planet, and we really don’t know what the end point is going to be.”

Climate change was the topic of Kolbert’s earlier guide, Field Notes from a Catastrophe. Her analysis for the brand new guide took her around the globe, to oceans, rain forests and mountains — in addition to a spot almost in her yard — the place scientists are learning disappearing vegetation and animals.

“Amphibians have the dubious distinction of being the world’s most endangered class of animals,” she writes. “But also heading toward extinction are one-third of all reef-building corals, a third of all fresh-water mollusks, a third of sharks and rays, a quarter of all mammals, a fifth of all reptiles and sixth of all birds.”

Interview Highlights

On how we outline mass extinction

The definition, I suppose, could be many, many organisms throughout many, many various teams. And that’s, actually, what we’re seeing and that’s what makes scientists worry … that we’re in a mass extinction. … About 1 / 4 of all mammals are thought of endangered. … About 40 % of all amphibians are thought of endangered. But we’re additionally seeing organisms, invertebrates, for instance, are endangered … many species of reef-building corals at the moment are thought of very, very endangered.

So you are seeing extinctions throughout all kinds of teams, and that, I believe, must be one of many defining traits of a mass extinction.

On carbon emissions affecting ocean acidity — local weather change’s “evil twin”

What occurs while you put CO2 into the air is that you just’re additionally successfully pumping it into the oceans, as a result of wherever the floor of the oceans and the environment meet, there’s simply an trade of gases. So a couple of third of the CO2 that we put up yearly — and that is within the order of 10 billion metric tons — is making its means into the oceans. And when CO2 dissolves in water it varieties an acid. It’s known as carbonic acid … decreasing the pH of the water. If you are a marine organism and … your complete atmosphere is the water and you modify the chemistry of the water, that may have very, very profound results. …

[It’s] world warming’s equally evil twin … and from the attitude of the broad expanse of life, there have been a couple of moments in time the place the oceans have turn out to be acidified, not essentially acidic however acidified … and they’re related to among the main crises within the historical past of life.

On a examine that examined how CO2 emissions affected marine life

If we proceed at our current charge of CO2 emissions, then by the tip of this century … [extrapolating from this study,] you are eliminating a 3rd of the creatures within the ocean as a really tough estimate. And then as you … get nearer and nearer to [underwater gas vents] — so even past what we anticipate on the finish of this century — if we type of proceed past that time, then you definitely’re getting to some extent the place your oceans actually begin to look type of just like the underwater equal of a vacant lot.

On the extinction of the Panamanian golden frog

There’s a frog often known as the Panamanian golden frog, and it is a lovely, stunning frog. It’s type of a taxicab-yellow frog with very skinny legs and arms and it is thought of a good-luck image. … These yellow frogs have been simply throughout. … And then this scourge got here via, which seems to be a fungus, a fungal illness, and simply wiped them out. And what occurred is that scientists realized — as a result of that they had seen this sample earlier than, they really anticipated this — and so they took a few of them out of the forest right into a conservation middle … and they’re breeding them there. There are nonetheless Panamanian golden frogs on this middle, however they can’t return out into the world into their very own native habitat as a result of this fungus remains to be there, and the fungus survives though the frogs now not do.

Barry Goldstein / Henry Holt & Co.

/

Henry Holt & Co.

On a idea of how the fungus unfold

One idea — it has been very tough to pin down — however it’s that this fungus was moved around the globe. Another actually fascinating story on frogs [is that they] have been used within the ’50s and ’60s for being pregnant exams. Something known as the African clawed frog, when you inject it with the urine of a lady who’s pregnant, it is going to lay eggs in a short time. And obstetricians used to maintain complete tanks of those frogs of their places of work. And the African clawed frog seems to be a frog that carries this fungus however would not appear to be killed by it. So one idea is that as these frogs have been [exported] around the globe, they carried this fungus with them … so we introduced the frogs and the frogs introduced the fungus.

On how individuals have disrupted ecosystems by bringing vegetation and animals with them once they journey

Rats have been introduced with very early Polynesian settlers within the Pacifics, in order that they have been delivered to locations like Fiji and so they wreaked havoc. Already, say, 1,500 years in the past. …

I believe what has modified is the size and the speed. For instance, it has been estimated that simply in ship ballast now in our huge supertankers, persons are transferring 10,000 species a day around the globe. So though our ancestors have been already at this venture and did trigger important results due to that, and important numbers of extinctions, we’ve simply ramped it as much as a complete new degree.

On bats dying off

Bats simply [started] dropping useless abruptly … round 2007. It occur[s] that the epicenter of this was proper close to the place I stay … in Western Massachusetts. This was first observed in Upstate New York. Right because it occurred I used to be in a position to exit with some scientists to a collapse Vermont, which was the most important bat hibernacula in New England.

So bats within the northeast hibernate within the winter, they go right into a state of torpor, they hold by their toes. They attempt to discover a place like a cave the place the local weather goes to stay fairly secure over the winter, and their physique temperature drops nearly to freezing, so you may see ice crystals on them numerous instances. And they simply hold there, fully immobile — it is an incredible factor to see. In this bat collapse Vermont, they have been significantly exhausting hit. They simply began to drop from the highest of this cave to the ground in these enormous drifts of useless bats. I went out within the winter of 2009, and it was a completely ugly scene of a carpet of useless bats.

On how ecosystems get well from mass extinction

After a mass extinction, it has typically tended to take many thousands and thousands of years for all times to get well. It’s not one thing that you just bounce again from, from sooner or later to the subsequent.

Copyright 2023 Fresh Air. To see extra, go to Fresh Air.