05/10/2019

One Million Animal And Plant Species Are At Risk For Extinction

11:45 minutes

a sea turtle with ashy texture lying dead on a beach with people in the background
The sea turtle is among the one million species that is threatened by human interventions. Credit: MarvinBikolano via Wikimedia Commons

According to a new UN report on global biodiversity, as many as one million species—both plants and animals—are now at risk of extinction, according to a new UN report on global biodiversity. That number includes 40% of all amphibian species, 33% of corals, and around 10% of insects.

One might assume that this type of devastating species loss could only come as a result of one thing—climate change. But in fact, as the report highlights illustrate, it’s deforestation, changes in land and sea use, hunting, poaching, pollution, invasive species—in short, human interventionsthat are causing species to disappear at a rate tens to hundreds of times higher than what has been seen over the last 10 million years.

Walter Jetz, professor in ecology and evolutionary biology at Yale University, joins Ira to discuss why the damage we do to biodiversity in our lifetimes may never be undone.

Plus, amphibians are sometimes thought of as the “canary in the coal mine” when it comes to a biodiversity crisis—they are affected by rising global temperatures, deforestation, and invasive fungal diseases. A new study by Dr. Jetz and his team published in Current Biology this week reports that over 1,000 amphibian species have been newly assessed as threatened or endangered.


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Segment Guests

Walter Jetz

Walter Jetz is a professor in Ecology and Evolutionary Biology at Yale University in New Haven, Connecticut.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Coming up in a little bit, Emily Oster, author of Cribsheet is here to answer your parenting questions with research, what the evidence says about long-term benefits of breastfeeding, the effects of daycare on development. What would you like to know? You make the call, but only if you make the call, 844-724-8255, 844-SCI-TALK, or tweet us @scifri. 

First, you might have heard the news this week that as many as 1 million species, both plants and animals, are now at risk of extinction according to a new UN report on global biodiversity. That number includes 40% of all amphibian species, 33% of corals, and around 10% of insects. 

Now, you might assume that this type of devastating species loss could only come as a result of one thing– climate change. But as the report highlights, it’s a perfect storm of deforestation, changes in land and sea use, hunting and poaching, pollution, the introduction of invasive species. In short, a whole bunch of human activities that in addition to rising global temperatures are causing species to disappear at a rate, quote, “tens to hundreds times higher than what we’ve seen over the last 10 million years.” 

For example, over 1,000 amphibian species, sometimes thought of as the canary in the coal mine of biodiversity crises, have been newly assessed as threatened or endangered according to a new study out this week in Current Biology. Walter Jetz, who is the lead author on that study, and also one of the authors on the recent UN biodiversity report joins me to talk about them both. He is Director of the Center for Biodiversity and Global Change at Yale University. Welcome to Science Friday. 

WALTER JETZ: Thank you. 

IRA FLATOW: Now, the report highlights say 1 million species are threatened with extinction. What proportion of species on Earth is that? 

WALTER JETZ: The report assumed that about 8 million species are on Earth and that’s obviously very highly debated number. We can have a whole separate program on the scientific debate on that. And however, I think it’s fair enough to use it as an initial ballpark. Many scientists would argue it’s many, many more, perhaps twice, three times, four times as many that are yet to be discovered. 

Only about 1, a little over 1 million are described right now. So this report is making the assumption, well, let’s say there are about 8 million species in total. We have assessed about 100,000 species formally to date through an expert process. And out of that, if we run the proportions against the various groups and then extrapolate from there, then that would get us to about a million out of the 8 million species threatened. 

IRA FLATOW: And was this very surprising about just how many would become extinct? 

WALTER JETZ: Oh, no. It doesn’t surprise me at all, and I worry. And in fact, our study points out that the number may even be larger. Certainly, for amphibians, that’s what we find. And we can talk more about that in a moment. It’s not surprising at all. And I would say it’s actually a conservative estimate because insects, for example, have only been assessed in a very limited way. 

The percentage, and I think you mentioned, that comes from that statistic for insects is about 10% being thought of as being threatened right now. But they’re really the ground portion of that 8 million species that are being talked about here. And that 10% estimate, right now, comes from a very small number. It’s mostly European bees. And a lot of tropical biodiversity has not even been assessed at all. 

IRA FLATOW: I think people may be surprised to see how much of human activity’s involved in the extinctions of these and not just climate change. But we mostly hear about climate change and the environmental movement. Is it so focused on climate change as some of these other human activities like poaching and pollution, which were once a big deal for environmentalists don’t get enough attention? 

WALTER JETZ: Well, I wouldn’t argue that. But we need to think about climate change. And some of the species threats that we are talking about here are actually climate change driven. We are already seeing the effects of climate change on some species populations. And this is the big issue to think about going forward. 

But already now, we have seen over 800 vertebrate extinctions since the medieval times, as you said, orders of magnitude– you summarized it beautifully– orders of magnitude more than expected from a background rate of extinctions. And we have a very clear connection between these various impacts that you have mentioned– deforestation, land use change, invasions, et cetera, et cetera on species. So the evidence is there. 

And I agree with you that there should be more attention to the benefits that we humans get from nature and we get them now that we are losing day by day by day through stuff that’s actually much, in some ways you could argue, much easier to manage and control than climate change. And there’s no reason– obviously, we need to think and do something about climate change. But a lot of the impacts we’re talking about here that are driving species to extinction and make us lose nature’s benefits are due to local and regional decisions that could be very easily affected by us getting involved, for example, as people. 

IRA FLATOW: I don’t think people really appreciate what is out there in biodiversity, why biodiversity and loss of it is so crucial. I mean, there are drugs and potential cures and stuff out there in nature where we have seen them before, which we may never even know about because they’ll be gone. 

WALTER JETZ: That’s right. And don’t forget, there are some species we haven’t even discovered yet. And we may lose them before we have even discovered them and before we could enter them into the equation. And the benefits we get from nature are manyfold. 

And it was great to see that report come out. It was the hard work by hundreds of scientists over the past years. It is an IPCC-type process. And thankfully, the governments are now involved in actually discussing this report and thinking about, then, policy changes from there. 

So it’s a wake-up call. And it’s a really important wake-up call about the ongoing loss of biodiversity of species and ecosystems. And we are talking about, for example, there was already an earlier UN report on pollination services. So the bees, for example, are providing billions of dollars of pollination services to us humans annually. If you think about insect feeding animals– and frogs, actually, are a really important group in that regard. 

IRA FLATOW: Well, let’s get to that, your amphibian study. You published a separate study this week about amphibians, which we always think as the canaries in the coal mine about the state of the environment. 

WALTER JETZ: Exactly. So think about amphibians, the frogs, toads, salamanders, et cetera. They are actually– you would think, well, what’s that amphibian species going to do for me? However, as a group, they are not just canaries about the health of the environment overall and, thereby, many other benefits that they derive from nature, but they also carry benefits very directly, as they are really important pest controlling animals that provide unmeasured, unfortunately, services on a daily, annual basis everywhere where they occur. 

They are also known to have a whole range of compounds that have medical purposes. So think about, many of you may have heard about the poison dart frog. So there are some species where the skin of a single animal would have enough toxins to kill 10 humans. 

And there is actually another example closer to home, not quite as toxic, thankfully, the Houston toad. And highly threatened now, but similar to that poison dart frog that I mentioned, this species and others have toxins, serotonins, that have been serving really important purposes in medical research. And some of their natural compounds have supported a whole range of drugs. 

IRA FLATOW: Why are they, so to speak, being singled out by nature to disappear so quickly? 

WALTER JETZ: You know, they are getting hit from all sides. Amphibians are already getting it from all sides. They are highly impacted by, say, species invasions, invasive arts, for example, tackling a lot of the juvenile frogs here in parts of the United States and elsewhere. They are getting hit by land use change directly. 

They’re often distributed. They have very narrow ranges. They’re very restricted in that geographic range, compared to birds, for example. Their range is, on average, about six times smaller. So any human impacts that are happening, any deforestation that’s happening is much more quickly going to wipe out the frog than it’s going to wipe out a bird species. 

And moreover, as they have really interesting physiology that makes them very sensitive to the microclimatic conditions around them. So any small changes, even if they’re not losing habitat directly but something may have happened a few hundred yards away, may affect their micro climate and, thereby, impact their population. So they’re really dropping like flies right now. And they are among the vertebrates, the group that’s already seen the most extinctions in the last 100 years. 

IRA FLATOW: One quick question before we go, is there any way to turn this around by having governments or people become more aware and do something about this? 

WALTER JETZ: Well, first of all, I think thanks to the new research, new remote sensing, for example, new scientific approaches, the sort of big data modeling that we and others are trying to do, you can actually now begin to pinpoint the species that are most strongly threatened by extinction. And they pinpoint the places, thereby that, as we need to do triage– we never have enough funds, or resources, or time to do conservation– we can more effectively identify the places where we want to be active. 

And I think as we identify these places, we all can get involved in lobbying for this group and lobbying for these places. And some of these places are actually close to home. I mentioned that Houston toad. There are many other species close to home that are affected by habitat loss. And we can get involved now by supporting organizations that are setting up conservation activities by– perhaps even in our own backyards– do stuff that is just more supportive of nature and wildlife. 

IRA FLATOW: Thank you very much, Professor Jetz, for taking time to be with us today. 

WALTER JETZ: Happy to. 

IRA FLATOW: Walter Jetz, spelled J-E-T-Z, who is very much involved in doing this. And he’s Director of the Center for Biodiversity and Global Change at Yale University.

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