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Scientists: Climate Change May Wipe Out a Third of World's Parasites, with Disastrous Ripple Effects

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As the United States continues to deal with unprecedented floods and hurricanes, a new study has revealed climate change is also driving the mass extinction of parasites that are critical to natural ecosystems, and could add to the planet’s sixth great mass extinction event that’s currently underway. The report in the journal Science Advances warns that about a third of all parasite species could go extinct by 2070 due to human activity. The loss of species of lice, fleas and worms could have profound ripple effects on the environment and might pave the way for new parasites to colonize humans and other animals with disastrous health outcomes. We speak to Colin Carlson, lead author of the report "Parasite biodiversity faces extinction and redistribution in a changing climate." He’s a Ph.D. candidate in environmental science, policy and management at the University of California, Berkeley. In 2011, Business Insider included him in a roundup titled "16 of the Smartest Children in History," alongside Mozart and Picasso. At the time, he was 15 years old. He is now 21.

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AMY GOODMAN: As the United States continues to deal with unprecedented floods and hurricanes, a new study has revealed climate change is also driving the mass extinction of parasites that are critical to natural ecosystems, and could add to the planet’s sixth great mass extinction even that’s currently underway. The report in the journal Science Advances warns that about a third of all parasite species could go extinct by 2070 due to human activity. The loss of species of lice, fleas and worms could have profound ripple effects on the environment and might pave the way for new parasites to colonize humans and other animals with disastrous health outcomes.

For more, we’re joined by Colin Carlson, lead author of a report published last week which revealed climate change is driving the mass extinction of parasites that are critical to natural ecosystems. He’s a Ph.D. candidate in environmental science, policy and management at the University of California, Berkeley. Still with us, Elizabeth Kolbert, the Pulitzer Prize-winning journalist for The New Yorker magazine. Her latest piece, coming storms. She reports extensively on climate change.

So, I wanted to start with Colin Carlson. Talk about what is happening to parasites in the world and why it matters.

COLIN CARLSON: Good morning. So, I think the key thing that we need to get out there is that there’s a lot of things about climate change we still don’t know. We’ve spent a lot of time in the last 15, 20 years focusing on the extinction of big charismatic wildlife, and we’ve thought a little bit about how that might impact their parasites. But the direct impacts of climate change on parasites haven’t been as well studied. So our research comes out and sort of does this global survey and really thinks through, OK, how good or bad could climate change be for parasites? And it turns out that parasites follow the same logic most species do: A handful do a little bit better in a changing climate, and the vast majority actually do a lot worse. They lose a lot of habitat. They lose their hosts. They face very high extinction rates.

AMY GOODMAN: So, talk about why parasites are important in the world.

COLIN CARLSON: So, I think one of the really cool things about parasites is that we have undervalued them for decades. And that means that when it turns out they actually serve important roles in ecosystems, it’s all the more surprising. Parasites are a huge part of what holds ecosystems together. They can be the majority of biomass in an ecosystem. They can be 80 percent of the links in a food web. They control wildlife populations. They keep populations down, just like predators do. And just like predators in the 18th and 19th century when we were eradicating them, parasites are, obviously, a hard sell. But it turns out they play this important regulatory role. And what we think could happen in a changing climate is, with these very high extinction rates, the loss of that stabilizing role could produce opportunities for new patterns of wildlife in human disease that are genuinely concerning.

AMY GOODMAN: So you say that parasites are among the most threatened species on Earth. Now, it may be hard, Colin Carlson, in the world you’re in, as a scientist, to understand how difficult it is for laypeople to understand this, but assume no knowledge when it comes to parasites, why they’re important. Most people would think, "Great! It’s good to get rid of parasites."

COLIN CARLSON: So, I think the important thing—right?—is that, for one thing, the majority of parasites never affect humans. There are over 300,000, potentially, species of parasitic worm on Earth. And of those, a handful, maybe up to a thousand at most, affect humans. A very similar thing is true for wildlife parasites. We have this idea that parasites are probably not good most of the time. But most of what they’re doing in ecosystems is just directly interacting with wildlife species. Most host-parasite relationships are stable. They’re at some sort of equilibrium, just like most ecosystems are, without environmental change. What we think is going to happen is the destabilization of those pairs, of parasites and their hosts. And just like with, I think, most things in climate change research, the sort of overarching maxim is that change is bad. There’s a massive predictive crisis. There’s a lot of species we still don’t know what the impacts will be. And so, on average, changing things from the way they are is probably actually not a good thing.

AMY GOODMAN: Can you give us some examples of common parasites?

COLIN CARLSON: Sure. Well, there’s a lot of parasites in the news these days, right? I’m from Connecticut originally, and so Lyme disease is always in the news, and we always have deer ticks in the news because of it. And deer ticks are one of those rare species in our study that gains a lot of range. But there’s also a lot of ticks on Earth that are threatened. There’s a lot of worms on Earth that are threatened.

To get back at this role that parasites play, I think one of the most incredible cases that we found in our research is these horsehair worms in Japan. They change the behavior of crickets so that they jump into streams, and that ends up being the majority of the food that endangered Japanese trout eat. So, even though parasites are manipulating host behavior, they’re literally moving energy through an ecosystem and keeping actually endangered wildlife populations stable. And a lot of species like that are the ones in our study that are threatened with extinction.

AMY GOODMAN: Colin Carlson, I just wanted to ask about your very interesting background. Our audience might be surprised to know you were born in 1996. You’re what? Thirty-one now? You enrolled—21 now.

COLIN CARLSON: Something like that.

AMY GOODMAN: Twenty-one.

COLIN CARLSON: Twenty-one. There you go.

AMY GOODMAN: Twenty-one now. You enrolled at the University of Connecticut at the age of 12. By the time you were 16, you had also obtained a bachelor’s degree in ecology and evolutionary biography—biology, and another in environmental studies, as well as a master’s degree in the same subject. In 2011, Business Insider included you in a roundup titled "16 of the Smartest Children in History," alongside Mozart, Picasso and the chess master Bobby Fischer. So, you’ve been doing this for quite some time now, but you’re only 21 years old.


AMY GOODMAN: I’m wondering about the climate you find yourself in right now, so to speak, the climate going to the top of the country, to President Trump, who talks about climate change as a hoax perpetrated by the Chinese. How does this affect your work and your colleagues’ work, your friends’?

COLIN CARLSON: So, a few things on that. I grew up in a rural town in Connecticut where climate change was a very taboo topic. And when I go home, I think it still is. I think that that’s one of the things that has pushed me towards this kind of research. I think that in the context of not just the current administration, but the current challenge that we face in terms of communicating science to the public, it’s incredibly important that we are transparent and honest about sort of the full impacts of climate change, the fact that, yeah, maybe one or two parasite extinctions might be good, the vast majority are bad. We have to give these balanced perspectives. I think that level of transparency is a huge part of how we continue to sell climate change research.

More broadly, I would say that a lot of my colleagues, a lot of folks that I work with, a lot of the people who have collected data that are part of our study, are very worried about the continued status of climate change research in the United States. A lot of our study relies on museum collections, and those are a huge foundation of biological research. We have to have museum collections to understand change over time. There’s really no way we could have ever done our study without them. And I know a lot of folks are worried about museum collections and other biological collections being defunded in the coming years. We’re already seeing some funding cuts for graduate research in ecology and evolutionary biology. Hopefully, those won’t translate into more funding cuts. But I think that in the coming years it’s absolutely critical that we continue to support those programs, we continue to fund research that makes the links between where we’ve been ecologically and where we’re going. Yeah.

AMY GOODMAN: Explain, though, more why museum collections matter.

COLIN CARLSON: So, our study is reconstructive in a lot of ways. It’s the first to map out this many species of parasite at once. And the way that we do that is we look for records of where parasites have been, to reconstruct their habitat. It’s a very top-down approach. So, the way that we end up doing that in practice is we take a set of museum specimens that have coordinates attached to them. You know, it’ll be an island in the Pacific, and we’ll have the longitude and latitude. And that goes into a database that feeds our models.

Our study is based in large part on the U.S. National Parasite Collection, which is currently housed at the Smithsonian. There’s over 20 million specimens in that collection. We’ve mapped out 150,000 records for this study. And I would say those almost exclusively come, in some form or another, from either field research by biologists or from museum collections.

We use collections in a lot of research this way. We use it to say, "Here’s where species have been. Here are the conditions that they’ve been found in. Here’s how we can inform our projections of their future, based on those records." And so, this is an absolutely indispensable role that collections play.

AMY GOODMAN: I wanted to bring Elizabeth Kolbert back into the conversation, author of The Sixth Extinction. Can you put Colin Carlson’s work, the significance of this report, in context and explain further the sixth extinction?

ELIZABETH KOLBERT: Well, the sixth extinction, we’re referring to the idea that we’re in a mass extinction event, so that there have been five, what are called major mass extinctions, over the course of the history of, you know, multicellular life, so over the last half a billion years or so. And the most famous of all these is the fifth. It’s the event that did in the dinosaurs 66 million years ago, which was, in all likelihood, caused by an asteroid impact.

So, now the idea is that because of what we humans are doing to the planet, we have extremely elevated extinction rates. And we are either—you know, by different people’s definitions, we are heading into, we are in, another mass major—you know, potentially major mass extinction event. Now, one of the hallmarks of a mass extension event is that you get extinctions across all different groups of animals, so from the very tiny to the very, very large. It’s sort of an indiscriminate event and takes out a lot of different groups at the same time. That is the very definition of a mass extinction event. So, if you were in a mass extinction event, then you would expect very elevated extinction rates, as I say, across all—virtually all groups, including our friends, the parasites.

AMY GOODMAN: And what most interested you, Elizabeth Kolbert, about this Science Advances report, Colin Carlson’s work?

ELIZABETH KOLBERT: Well, I think Colin makes a really important point, which is that we are always—you know, everyone is aware tigers are in terrible trouble, elephants are in terrible trouble, giraffes are in terrible trouble, you know, and so we’re always talking about—almost always talking about really charismatic animals and what’s happening to them. But E.O. Wilson makes the point—I’m not sure I’m quoting him directly, but it’s the little things that run the world. It’s really, you know, very tiny invertebrates and microorganisms that make the world work and the way we know it. And so, when you’re messing around with that, when you’re messing around with the very tiny world that we’re not really paying a lot of attention to, you can get some really, really big impacts that you didn’t anticipate, as I say, in part because you didn’t even know what was going on.

AMY GOODMAN: We were talking about the political context that is taking place right now in Washington. President Trump has just nominated the Republican Oklahoma Congressman Jim Bridenstine to head NASA, the National Aeronautics and Space Administration. Bridenstine has no science credentials, has repeatedly denied the human impact on climate change. NASA conducts a significant amount of global climate change research. In 2013, Congressman Bridenstine took to the House floor to demand President Obama apologize for funding climate change research.

REP. JIM BRIDENSTINE: Global temperatures stopped rising 10 years ago. Global temperature changes, when they exist, correlate with sun output and ocean cycles. ... Here’s what we absolutely know. We know that Oklahoma will have tornadoes when a cold jet stream meets the warm Gulf air, and we also know that this president spends 30 times as much money on global warming research as he does on weather forecasting and warning. For this gross misallocation, the people of Oklahoma are ready to accept the president’s apology, and I intend to submit legislation to fix this.

AMY GOODMAN: So that was Oklahoma Congressman Jim Bridenstine, who President Trump has now nominated to be head of NASA. I want to get both of your responses, beginning with Elizabeth Kolbert.

ELIZABETH KOLBERT: Well, unfortunately, he’s a pretty characteristic nominee of this administration to positions that have traditionally been held by very eminent scientists. And you’re seeing this sort of wholesale undermining of science, scientific inquiry, at the top of the U.S. government. And you have to say yourself, you know, "Whom does that benefit?" It does not benefit scientists, and it certainly doesn’t benefit the public. So there’s obviously an agenda here. And it’s pretty—as I said, it’s a pretty scary one. When you’re having people at the very top of the U.S. government who are basically peddling patent medicine, it’s really, really not a happy situation.

AMY GOODMAN: And, Colin Carlson, as a scientist yourself, your response?

COLIN CARLSON: I think it’s incredibly concerning to see science not only deprioritized, but actively worked against, by the administration. The view from the ground is that a lot of researchers are incredibly worried about our ability to keep doing research that is scientifically ethical, that is valid, that presents issues like climate change objectively, and our ability to continue to be funded to do that research. I think this is one in a set of decisions by this administration that really do give us reason to be worried.

That said, I think there is some silver lining in that I know that this has brought out a lot of passion among scientists who I work with and scientists across the country. I think this is giving us a chance to really shine as a community. And I think that this might, in some inadvertent ways, lead to a really productive four years of research.

AMY GOODMAN: And, Colin Carlson, in your report on parasite biodiversity facing extinction and redistribution in a changing climate, what most surprised you?

COLIN CARLSON: I think one of the really cool results, buried a little bit in the study, is that with the kind of models that we use, human parasites or parasites that spread human diseases, like that deer tick, don’t actually have any inherently better or worse chance in a changing climate. It’s kind of a lottery. And we’ve known this about climate change and extinctions for a while. We know that there are factors that make some species do better and worse. There’s variation between groups. But really, for parasitic species, because they’re dependent on wildlife and because wildlife are already threatened at such a high rate, what we think is going to happen is a pretty high across-the-board extinction rate, like Elizabeth was talking about, regardless of whether that affects humans or wildlife. I think the rates that we are predicting are shockingly high, and it’s definitely a lot more than we expected going in.

AMY GOODMAN: I want to thank you both for joining us. Of course, we’ll continue to discuss this issue, the issue of the intensity and frequency of hurricanes and climate change. Colin Carlson, co-author of the piece, "Parasite biodiversity faces extinction and redistribution in a changing climate." Elizabeth Kolbert, the Pulitzer Prize-winning author of The Sixth Extinction, her latest piece in The New Yorker magazine, "Hurricane Harvey and the Storms to Come." Thanks so much for being with us.

When we come back from break, we’ll go to Florida to talk with the prize-winning author Edwidge Danticat, Haitian-American writer, who also had to take cover, had to evacuate. And we’re going to talk about the—hear from voices of survivors of the Mexico earthquake and speak with Kim Ives about what took place in Haiti when Hurricane Irma struck. Stay with us.


AMY GOODMAN: The Cuban singer Silvio Rodríguez, singing live at Central Park SummerStage last night. This is Democracy Now!,, The War and Peace Report. I’m Amy Goodman. At least four people have died and nearly 6 million people are without power in Florida, after Hurricane Irma made landfall Sunday in the Florida Keys as a Category 4 hurricane. The storm also flooded the streets of downtown Miami, turning Miami’s main strip, Brickell Avenue, into a three-foot-high raging river. The storm sparked one of the largest mass evacuations in U.S. history, with nearly 7 million people ordered to leave their homes.

We go now to speak with one of them. We go to Florida to speak with the award-winning Haitian-American writer Edwidge Danticat. She lives in Miami but had to evacuate to Orlando.

Edwidge, how are you? Where are you now? And your thoughts on what’s taking place in your state?

EDWIDGE DANTICAT: Good morning, Amy. Thank you for checking in. I am fine. I’m doing much better than a lot of other Floridians. We had to evacuate on Thursday, because the area that I live is not too far from downtown Miami, and it’s close to a bay. And so we’re part of an extended evacuation area. So we decided, actually, two hours’ notice, on Thursday, to drive up to Orlando, where we have friends. And the road was really—I’ve never seen anything like that. We were driving about 10 miles an hour most of the way because of—you know, we were among some of the 6 million or so people who were told to evacuate. So, it was a very long drive, with a lot of folks also leaving. And we got to Orlando, hoping for a weaker version of the storm. We didn’t—gas was very—there is a lot of shortage of gas, so people—we couldn’t clear the state totally. So we stayed in Orlando with some friends, where the storm did come last night in a weaker version. There was a lot of wind. And I’m not sure what the damage is out there now, because we haven’t been able to go out. We don’t have any power where I am, as most of something like 3 million Floridians don’t have power. But we’re OK. And we are happy to survive, and are ready to return and see what happened, what we can do to help.

AMY GOODMAN: I wanted to ask you about an issue that also plagued people as Hurricane Harvey was hitting Texas, where, in Houston, something like 85,000 young people have DACA status, are allowed to stay, live and work in this country, and in the midst of the horror of that hurricane, President Trump pulls DACA. I wanted to ask you about temporary protected status for more than 50,000 Haitians, their status set to expire in July. But after pressure from immigrant rights activists, the Trump administration extended the temporary protected status for six months, meaning they could again face the threat of deportation in January. Are you hearing concern about this, as people are fleeing, as millions were forced to evacuate? Edwidge?

We may have just lost Edwidge Danticat, who was speaking to us from Orlando. She actually lives in Miami, but she is one of the 7 million evacuees in Florida.

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