Science Friday - Urban Forests And Climate Change, HIV Treatment Progress. September 4, 2020, Part 1

Episode Date: September 4, 2020

New York City’s skyline is dominated by tall skyscrapers—but there’s a surprising amount of forest in the city known as a concrete jungle. Tree canopy actually covers about 20% of the city. In fact, woodlands are one of the few natural resources the city has. Reporter Clarisa Diaz, in collaboration with John Upton from Climate Central, shares how the city’s green spaces, both large and small, are needed to create an urban forest ecosystem in the face of climate change. Plus, forester David Nowak talks about the science behind planting an urban forest, and how to determine the value of a tree. Plus, while all eyes are currently on the COVID-19 pandemic, the coronavirus isn’t the only disease circulating the world. Lockdowns have hindered access to medical care, and supply chains for both tests and medications have been disrupted. With countries allocating limited public health resources to battle COVID-19, longstanding public health threats like tuberculosis, malaria, and HIV/AIDS may be at risk of resurging. However, there is also hopeful news for communities facing HIV/AIDS. Last week, a study published in the journal Nature examined 64 unusual people who seem to be able to naturally keep HIV at bay. Researchers investigated what makes these so-called ‘elite controllers’ able to manage their infections. They now think powerful T cells—a type of white blood cell which helps regulate the immune system—may hold a clue to these cases. Furthermore, earlier in the summer, a trial of a long-lasting injectable drug to prevent HIV infection was found to be at least as protective as the existing “pre-exposure prophylaxis,” or PrEP drug, which must be taken daily. Health and science reporters Apoorva Mandavilli of the New York Times and Jon Cohen of Science join Ira to discuss recent HIV/AIDS developments, and to reflect on 40 years of AIDS research.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. Contradicting multiple expert opinions about when a COVID-19 vaccine should be available, the CDC told states they should be prepared to distribute a vaccine by the politically advantageous date of November 1, two days before the elections. When a COVID-19 vaccine finally becomes available, who should get it first? Researchers are starting to think ahead because, well, they don't have an easy answer. For example, this week, two groups released proposals, one prioritized first responders and health care workers. The other said giving it to people with known comorbidities was the most ethical option. Here to give us a rundown on those proposals and other science stories of the week is Amy Nordrum, editor for MIT Technology Review. Welcome back, Amy. Thank you, Ira.

So experts don't expect a coronavirus vaccine anytime in the near future, but people are starting to plan ahead for how one will get distributed when it does become available. Amy, can you give us a rough outline of the two plans proposed this week? Yeah, certainly. I mean, it's a very important question, and the two groups that put their proposals out this week are thinking about that question very differently. So one proposal came from the National Academies of Sciences, Engineering, and Medicine. It laid out a four-phased approach with medical workers being the first to get the vaccine, as well as elderly people living in nursing homes and those with pre-existing conditions who might be at higher risk. And then later on in phase two, that would include groups of people like teachers, people living in prisons, people living in homeless shelters. And then later in the week, a group of medical ethicists, 19 from around the world, put out a different three-phased model in a paper in science. They said a vaccine shouldn't necessarily go to health care workers and the elderly in certain

countries first, but it should be distributed globally based primarily on how many premature deaths it would avoid. So they wanted to look at the total population around the world and get the vaccine to those people at highest risk of death or permanent damage no matter which country they live in. So there's clearly different ways to think about this approach, even among the experts. Could there be two plans at once, two different plans? There certainly could be. There could be as many plans. as governments or organizations decide to pursue. There is one global organization called Kovacs right now.

It's an alliance between the World Health Organization and a group called the Gavi Alliance. That's really trying to spearhead a global effort to help with vaccine distribution around the world. Dozens of countries have signed up for that. But the U.S. is not planning to be a part of that, at least not at this time. So it very well could be a patchwork approach where different governments and organizations decide how they want to roll it out for themselves. So it's going to be like we have with the states now on their own. When the vaccines come out, the states will be still on their own without any central guidance. You know, it could be that. It could be in the U.S.

It could be a state-by-state decision. I mean, it could be a more federal organized approach. But, you know, it's not clear at this time. And there's still a lot of conversations around it. I don't think these are going to be only two proposals that come out around this question. I think, you know, we'll expect to see others. And the discussion will definitely continue. No one coordinating this effort then?

Not right now. I mean, the Kovacs Alliance with the World Health Organization and the Gavi Alliance is probably the best leading effort in that regard. But, you know, there's big players like the U.S. that haven't signed up for that. So, you know, there's not really a central global effort at this stage. Okay, let's move on to a story that is kind of really interesting because I'm a physics geek and I like these things. There was a discovery made by the gravitational wave detector LIGO this week. Now, I remember when a LIGO announcement would have been front-page news. Remember when that happened?

And now it's sort of buried under the virus headlines. Tell us about what the scientists discovered. Yeah, you know, I guess LIGO, on average, is detecting gravitational waves about once a week now. So it has become a more common thing. But this week, they reported a particularly interesting detection. they recorded evidence of a merger between two black holes. And one of these holes was surprisingly large. It was so large, in fact, that they don't think it could have been formed in the typical manner that black holes are formed,

which is by a star collapsing. They think it might have been formed by two other black holes merging and becoming this larger one. And it's the first black hole of its size that they've been able to directly detect. So this is the biggest black hole ever detected is what you're saying. You know, there are bigger, black holes. It's sort of in the middle range. So we've actually detected smaller and larger black holes, but none in the middle range. And that's important because we don't really know how the biggest black holes have formed. And one theory is that they might form through a bunch of mergers of smaller black holes.

But if that were the case, you might expect to find black holes in this middle range. And until now, we haven't actually directly detected one. So in its range, it is the first to be detected. Well, I'm going to call it the Goldilocks black hole then, right? That's perfect. Right in the middle. Does this violate anything, any of the laws that we know about black holes, or is it just interesting because it's just in the middle range? It's not surprising.

We've seen black hole mergers before. This is the first that we've detected involving black holes of this size. So the merging isn't surprising. LIGO, actually, the first detection of gravitational waves that ever made was from a black hole merger. But the size is what's important here. The black hole involved, the bigger one, was about 85 times as massive as the sun. Wow, I can imagine the kind of gravity wave. That must have given off.

Right, quite a site for LIGO. Right, really. Let's go on to other space news. SpaceX, Elon Musk's company, added another 60 Starlink satellites to its network this week as part of its years-long project to offer global internet service. Give us a little update on that, if you will. Yes, on Thursday, SpaceX launched 60 more of these Starlink satellites into low Earth orbit from the Kennedy Space Center in Florida, successful mission. The company has now put more than 600 of these Starlink satellites into orbit.

It's building up a huge constellation with the goal of delivering global broadband internet service to anyone anywhere around the world. It'll start service in North America and then continue on from there. And it's been launching satellites into orbit for years now. And the company has now said that sometime this year, some people in the northern U.S. should be able to sign up for a public beta Internet service from them. So they're starting to move on to making this an actual commercial product. So a beta internet service, what does that look like? Will we just be able to open our laptops, see Starlink listed as an available Wi-Fi network?

You would have to use a user terminal that the company would provide. It's unclear whether the customer would buy it or whether that would come when you sign. sign up for internet service. It's a device that kind of looks like a tiny satellite dish that you would put in your home or outside of your home, and then you'd be able to connect to that kind of like a router to these satellites. So we're reinventing the satellite dish in some sort of way. Exactly. And, you know, the company has said that the speeds will be comparable to what's available now through broadband service through fiber optic cables. So it's, you know, I think sometimes we think of satellite internet service as being extremely slow. And the company is saying that's not the

modern version that they're going to provide. It will be as fast as, you know, anything else that you'd sign up for. You know, amateur astronomers have been pushing back on all these thousands, thousands and thousands of satellites that are going to be up there because they sort of spoil the view at night, don't they? Yeah, the company, I mean, they've put more than 600 into orbit already, but they have actually permission to launch as many as 12,000. So that is a lot of extra traffic in low Earth orbit that wasn't there before. Speaking of big companies taking on huge challenges, the FAA has given Amazon approval to deliver packages via drones. Now, we know that Amazon has been working on this for some time.

Why has it taken so long to get approval? Yeah, Amazon's been working on it for years. They're not the first company to get approval. So UPS and Google have also received FAA permission to do the same thing, investigate, package delivery by drones. And, you know, none of this means that these companies will start tomorrow. there's still several steps that would need to be completed. The FAA hasn't really spelled out exactly how drones should operate in cities and neighborhoods for a delivery service. So even though this was a big step for Amazon, there's a lot of regulations and figuring out what it means in terms of air traffic control and identifying drones in the air.

A lot of these details are still being worked through. So this will allow Amazon to start doing limited tests of drone delivery service with customers. customers. But although the company hasn't said kind of when or where those tests will begin. Yeah, I would imagine that we'd test it in a more sparsely populated neighborhood than in a big city. Because, you know, who knows where they could land if they miss a spot by a little bit. Yeah, a lot of the, you know, we've seen other drone delivery services test around the world. And often rural areas is the best place to begin these tests. And also could be, you know, where it makes the most sense to start because it takes longer to travel. longer distances there and package delivery through the air might make more sense from a commercial

perspective as well. We all know the old Euclidean, I guess axiom, a distance between two lines. The shortest distance is a straight line. Exactly. That's what they have in mind for this. So we'll see you know, how soon it happens. Let's go to the last thing. Scientists have discovered something cool about sea anemonez, one of my favorite topics because I used to have them in my aquarium. Yes, I do have some interesting news about sea anemones. These are the animals that clownfish love to hide inside. They have these tentacles that wave around in the water. Some anemones have 10 or 12 tentacles. Some have 24. Scientists didn't really know why certain inimities had more tentacles than others. But as it turns out, the more a sea anemone eats, the more tentacles it grows. And this is kind of unusual for an

animal because tentacles are appendages. So it would be like me or you growing an extra arm when we eat more. And it's the first time, to their knowledge, that there's an animal that grows more appendages based on how much it eats. Yeah, because we're used to plants, right? You feed a plant that gets healthier. It puts out more shoots or stalks. It grows, but you're talking about animals here. Yeah, in this sense, the anonymity is definitely acting much more like a plant in that regard than an animal as we traditionally think of it. Must make the clownfish happier, I'm guessing. That's right. I didn't try that in my aquarium, but if I had one, I would try that.

I'd watch for it. Thank you, Amy. Thank you. Amy Nordrum editor for MIT Technology Review. On the Science Friday Voxpop app this week, this is what we want to know. Are you deaf or hard of hearing? Have you tried any so-called cures to regain your hearing? We want to hear about your experiences.

That's on the Science Friday Voxpop app wherever you get your apps. We're going to take a break, and when we come back, tracking another worldwide virus, but this time it's more hopeful news, an HIV-AIDS update after the break. We'll be right back. This is Science Friday. I'm Iroflato. While all eyes have been on the COVID-19 epidemic, COVID is by far not the only disease around. Other global health threats from tuberculosis to malaria continue, and we're headed into the 40th anniversary year of the first public descriptions of what would come to be known as AIDS. Joining me now for an update on where the fight against HIV stands are two reporters covering diseases and global health. Apurva Mandevili, a health and science reporter at the New York Times, and John Cohen, senior correspondent at the journal Science.

Welcome to both of you. Thanks so much. Thank you for having us. Apurva, you wrote recently that while people were fighting coronavirus, some of the big global health issues from TB to HIV are being affected. Tell us about that, please. Well, as you know, Ira, HIV and TB and malaria are a huge problem in many parts of Africa and Asia and even Latin America. And in those places, the lockdown as well as the pandemic have really affected the efforts to contain those diseases. So it's really hard for people to get to clinics and be diagnosed.

It's difficult for them to get medication, and it's difficult for doctors to keep track of whether people are taking their medications on time. And all of those steps along the way are what we need to be able to control in order to prevent deaths from those diseases. I think a lot of people may not realize that tuberculosis is still the biggest infectious disease killer. And last year it killed about 1.5 million people. So these are not trivial diseases. Yeah, they have not gone away, even though they have gone off the radar screen, right? That's right. I think people think of TB as an old disease, and it is very much that, but

it's also very much present. And it looks like it is going to be an even bigger threat because of the pandemic and the coronavirus derailing all of the efforts to control the TB pandemic. Yeah, let's talk about that some of the resources, the supplies and tests that would normally have gone to those other diseases, are they being used up by the coronavirus? There is a test called the gene expert, which is used to diagnose TB, and it's a very effective diagnostic tool. But as it turns out, it can also be used to diagnose the coronavirus infection, which in many ways has been great for these countries because they were prepared to diagnose the coronavirus infections. But at the same time, it meant that in these,

places where there are very few resources, all of the people in the clinics and all of the resources went towards the pandemic. And all of a sudden, TB was again a back burner issue. And, you know, a lot of hospitals actually shut down everything except the coronavirus. And so all of the efforts in diagnosis went towards the virus and people are not being diagnosed with TB as much anymore. I mean, in some countries, diagnosis of TB have fallen by something like 70%. If you're not getting diagnosed, you're probably spreading it to other people, your disease is progressing, you're much more likely to get really sick, and you're much more likely to die. That's really sad news to hear. You wrote about difficulties in getting the drugs needed to prevent

mother-to-child HIV transmission, possibly causing a surge in HIV cases in Africa. Right. So we actually have very good drugs to prevent mother-to-child transmission of HIV. But one of the problems with the pandemic has been that the lockdown has made it really difficult to get the medications to where they're needed. Some of that is because there are only very few places where these drugs are made. For example, India is one of the places in China as the other, where most of these drugs are manufactured. And without being able to get the drugs into the countries, but also a lot of women are not showing up at the clinics because they're afraid of getting infected at the clinics or they're not able to because of the lockdowns. And so they're not getting the medications they need to prevent that mother-to-child transmission. So we will probably see and have already been seeing an uptick in the number of babies diagnosed at birth.

John, you've written, and so have you, Apurva, about a study that came out in nature last week, about people called elite controllers. John, what is that? Can you tell us about that? We've known for a long time that there are some people who become infected with HIV and the virus doesn't harm them. Over the years, their immune systems remain normal and they don't take antiretroviral drugs. And it's been studied intensively, but usually the studies are of three or four of these elite controllers. And they've found some hints as to why they control the virus.

and it does seem in some cases as though they have unusually good immune responses against the virus, but it doesn't explain everything. And this new study looks at 64 elite controllers in a very deep dive into their chromosomes and discovers something really eye-popping. The virus weaves itself its genes into our chromosomes, and they found that in the elite controllers, as compared to people on treatment, they more frequently, far more frequently, have the virus in parts of their genomes, in parts of their chromosomes that can't copy the virus. They don't have the machinery necessary to go from the DNA

of the virus into new viruses. So they're throwing the virus into what are called gene deserts. And that's a fascinating insight. It's going to be difficult to translate that to help everyone, because there are 38 million infected people, and elite controllers make up half of one percent of those people. But that's how progress happens. You crack open the door, and this tells us something we didn't know. Pretty rare is right. I mean, the researchers looked at 64 people.

That's not a lot of people, is it? Well, it's a lot of people considering how few of them exist. And the sequencing that they did of their DNA is really intensive. It's a tremendous amount of data. they looked at thousands of genome sequences of HIV in these people as compared to the control group. So it might not sound like a lot of people, but in reality the amount of data is a flood of new data that makes a really strong case that they're throwing their HIV DNA into these gene deserts. And it raises a provocative question of how did they do that? Why did they do that?

and it may well be linked to their immune responses. And the leading theory is that their immune responses got rid of the really good HIV DNA in their genomes. HIV wants to be inside of a gene. And genes only make up a percent of our genomes. You know, we have 3.2 billion DNA building blocks in us. Genes are a tiny part of that. HIV targets those. And these people selectively got rid of those.

That's interesting. Did they get rid of them forever? I mean, are they disease free? Can they be called cured now, John? You know, it's something of a philosophical question. No, they are not cured, but they're not on drugs, and the virus isn't harming them. In one person in this study of the 64, she had broken HIV DNA in her genome and no replicably. competent is the scientific nerdy words, but no DNA that could make new viruses.

She may well be cured because there's no evidence that she has any HIV in her that can make new HIVs. The other people all have evidence of HIV in them that can make new HIVs. And we've seen lots of cases of people who appear cured, who stop all treatment, and the virus comes back two, three years later. So it's a dicey problem. proposition to say someone is cured. But for all intensive purposes, they are quote-unquote functionally cured because they live their lives as though there's no virus in them. It doesn't do anything to them. Apurva, how different is this from other people that have been said to be, quote, cured of HIV? The virus eliminated over a long course of antiviral therapy.

Well, only two people have really been cured of HIV before this. The Berlin patient and the London patient, Timothy Ray Brown and Adam Casicejo, they both were treated for their cancers with a bone marrow transplant, which is an extremely invasive and risky procedure. And basically, they had their immune systems wiped out and they got a whole new immune system. This isn't something that we can really do for the 37 million people who are infected out there. So it's not really a very practical solution, but it gave us some hope that a cure is possible, that it is possible to completely get rid of HIV from your body. Now, this newest case, Lorraine Willenberg, she's been infected since 1992.

And as John was saying, there's really no virus, live virus left in her body that they could figure out can multiply itself. And so she is, for all intents and purposes, cured. One of the cool things about this study that they were able to do is they looked at just a massive, amount of her blood cells, which, you know, these are the kinds of things that we couldn't really do a few years ago. And they use techniques that are just very new and very cool to be able to look at enormous number of cells and to look everywhere in the genome. And they couldn't find any trace of virus. So the scientist that I spoke to seemed pretty comfortable

with calling her a cure. She had a funny response when I asked her, do you think you're cured? She said, I don't know why people ask me that. The virus has never done anything to me, so why would I be cured? Earlier this summer, John, there was some other hopeful news with regard to something called pre-exposure prophylaxis or prep. Tell us about that, please. So prep is the idea that's kind of like if you go to a country that has malaria, you can take drugs to prevent malaria. Well, you can do the same thing with HIV. The drugs that treat people for HIV, the antiretrovirals, they work as preventives. And that's what prep is. That was first approved by the FDA

in 2012. It's been around for a long time. And there's solid evidence that it works. The problem is that for it to work, you have to take daily pills. And a lot of people don't want to take daily pills who aren't living with a virus. And the advance that came out was an injection that offered better protection even than the daily pills. And that could last for a few months. Some people aren't going to want injections. Some people are going to want to take pills. It's kind of like contraception. Some people are going to want condoms. Some are going to want birth control pills. Some are going to want IUDs or diaphragms. But we have a menu available to prevent pregnancy. And the same idea is occurring in the HIV world.

Apurva, do you see this as changing the equation for people in communities affected by HIV? I mean, even financially, is this more competition in the prep drug market? Absolutely. I mean, we've only had one company in the space before, Gilead. They had Truvada, and then they more recently developed another drug called Descovy. And, you know, they've had basically a monopoly. And there's been a lot of issues with activists alleging that Gilead is, setting the prices way too high, that it's profiting from patents that the taxpayers helped to develop. And so it's always nice to have competition in the space. And this this prep option in

particular is really welcome because it's long acting and people wouldn't have to take the pill every single day. You know, there's also a lot of stigma associated with taking a medication like that. There are a lot of women in parts of the world. There are people who like to travel. For a lot of people, it's just not a very practical option to have to take something every single day. In this case, they would be able to just go and get the shot, and then that's it. You don't have to think about it for the rest of that period. I'm Ira Flato, and this is Science Friday. In case you're just joining us, we're talking about HIV-AIDS and other global health issues in the time of coronavirus with my guests,

Aperva Vili of the New York Times, and John Cohen, senior correspondent at the Journal Science. Let's zoom out and look at the big picture. We're heading into the 40th year since AIDS was really talked about in public. And I remember back 40 years ago, most of the money went into finding a treatment for AIDS and really we still haven't found a vaccine against it. As opposed to COVID-19, the majority of the effort is going on to finding a vaccine. We have hundreds of people looking for potential vaccines. John, what's your problem? perspective on that? In 1989, I started to work on a book about the search for an AIDS vaccine, and I had the foolish idea of proposing a book about one year in the search for an AIDS vaccine, and I sold that book proposal. It took me 12 years to complete the book. The book came out in 2001, and it was about why there wasn't an AIDS vaccine and how the field was in disarray. So HIV surfaces, and we don't know what causes AIDS.

We don't know that HIV is the cause. That takes several years. In the case of COVID-19, we know on January 10th, and some people knew earlier that there was a new coronavirus that resembled SARS. And you have to know what the cause is to make a vaccine. You can make a treatment for something without knowing the cause. It's better if you know the cause. but the truth is you can treat some diseases without really understanding cause. But a vaccine, that's not the case.

And HIV is a much more difficult virus to stop than SARS-CoV-2. And we know that for lots of reasons. Number one, most people who get SARS-CoV-2 recover and get the virus out of their body with their immune system. That's not what happens with HIV. And if you look at animal studies where you give a vaccine to the monkey and then challenge it with the virus, in the HIV world, the monkey model really struggled for many years and still struggles to show that you can protect monkeys with a vaccine. With SARS-CoV-2, almost everything works to some degree. So I'm incredibly optimistic.

And I think now I should do one year in the search for a SARS-CoV-2. two vaccine because it just doesn't look like that tough of a scientific problem. Apurva with studies like we've been talking about today, do you think we're looking towards a time when HIV will be controllable or even eradicated? It's looking more optimistic now in terms of the research than it has in a very long time, partly because we have learned all of these insights in the last few years. there is also a long-acting drug, the same company that made the long-acting preventive that we were just talking about, the PrEP, also has a long-acting drug that people would be able to take once every month or once every two months and not have to be treated every single day. I think there are a lot of really positive developments along those fronts, but to go back to what we were talking about earlier with the pandemic and that derailing HIV prevention and treatment efforts, I think the numbers, the next few years are going to be tricky again because we're losing a lot of progress during

this pandemic. And resources going towards the pandemic that might be going toward other diseases and even HIV, just bringing us back to where we started this discussion. Exactly. It looks like the pandemic is going to set us back by about a decade or 15 years if countries don't shell out the resources that they need to keep things on track. Well, we've run out of time. I'd like to thank my guests of Porva Mandivili, a health and science reporter at the New York Times, and a Science Friday alumn, and John Cohen, senior correspondent at the journal Science. Thank you both for taking time to talk with us today. Thanks for having us. Thanks so much, Ira. We're going to take a break, and when we come back, a look at trees, climate, and the big city. Stay with us.

This is Science Friday. I'm Iraflato. It's time to check in on the state of science. For WWNO, St. Louis Public Radio News. Iowa Public Radio News. Local science stories of national significance. New York City's skyline is dominated by tall skyscrapers, but even though the city is known as a concrete jungle, there is a forest among that jungle. Tree canopy covers about 20% of the city,

and woodlands are one of the few natural resources this city has. Clarissa Diaz reports how New York City is using, green space large and small to create an urban forest ecosystem in the face of climate change. In the heart of the Prospect Park woodlands, the coolness of the breeze is a relief from the heat on a summer's day. But it's not just any summer. It's a pandemic summer. I feel like Prospect Park is usually packed, but I have seen an influx of groups of people here for sure more since COVID. Taina and her friend Cherise have come to the park almost. every weekend since the summer began.

And for Tyena, it's quite a trek. I live in Bushwick, and it takes me a while to get all the way across Brooklyn. We don't have nature like this around the city, so you need a place that feels local, that feels accessible, that you can come to. For New York City residents cooped up in their apartments during the middle of summer, it's literal cabin fever. You know, we live in a pre-war building, and it kind of traps the heat in during the summer months. You can find a space that you can kind of call your own, or at least just escape.

It's cooler, you know, than hanging out by the concrete area. Yeah, concrete retains a lot of heat. On average, urban forests in the city are about five degrees cooler than their surrounding areas, according to the U.S. Forest Service. The average tree covers around 21% across the whole city, and the city contains from field samples. We estimate about 7 million trees. That's David Noak, senior scientist and eye tree team leader at the U.S. Forest Service. His team has developed an air temperature model, which looks at the weather conditions of New York every hour, along with the surface parameters around each site of trees in the city.

As you move more towards impervious surfaces and less away from trees and natural systems, you tend to get this greater heat-land effect. The urban heat island effect makes swathes of the city with fewer trees hotter in the summer. As temperatures become more extreme, residents that do not have adequate means of cooling down may become more vulnerable. I mean, the cities are hundreds of years old, and they have this infrastructure. and this history of being built, they are what they are, it's probably easier-designed parks as you develop a city in the beginning than trying to retrofit parks in afterwards.

Not that it can't be done, but there are a lot of problems in doing that. According to NOAC and other scientists, while more cooling can be achieved around a specific site with a grouping of trees, the spreading out of trees could lower temperatures across the city, though not as cool as a large park would, but could provide some relief where city dwellers live. You have two types of things going on, creating these respites of cool air temperatures in the parks that people can go to, but also, if you don't have access to those parks,

you want to create cooler air temperatures in and around the spaces where people are living, and individual trees can do that. One key to making sure trees can thrive in urban environments is maintenance. Street trees, for example, need to be ensured enough space for their roots to grow in proper soil conditions. The conditions for growing urban trees are specific to the site and the type of tree being planted. You've got to look at it from the forest perspective and not necessarily the single tree perspective, that you could have many trees of different sizes throughout an area that can create this cool of pocket.

It's like in a forest that stand. We have all sorts of tree sizes that create that cooling environment. The idea of planting a single tree in a larger system for reforesting the city through time makes the forest perspective unique from typical urban street landscaping, which may only take into account a particular neighborhood or site. What if tree plantings could be planned so that the cooling, effects in adjoining neighborhoods could be combined. John Jordan is the director of landscape management at Prospect Park Alliance. We're really one of the first parks in the city that started doing

organized forest management and the Prospect Park Alliance, even at its outset, was really oriented all around saving the forest and forest restoration. Jordan takes us on a tour of the park's restoration efforts, starting at the edge of the park's 526 acres. Those are we call perimeter woodlands. They're impacted in a really different way. They have more invasive species, more human impacts, things like that. So they serve as a buffer. And from a cooling perspective, they're super important. As we walk along the perimeter of the park,

there's more and more shrubbery. Once you get a little further, you'll see there's a fence and a bunch of green behind those trees. And that's going to be the start of our reforestation or aforestation project where basically we took a trees and turf area that was having a lot of negative human impacts. And we're starting to try to convert that back to like an actual woodland.

The landscape gradually turns into a more mature urban forest, showing distinct growth from one to four years of planting and maintaining trees. Those tulip trees are really doing well. They're filling in this space. And this is, you know, now we're looking at several years of growth of a really fast growing tree. This is meant to be kind of like a meadow planting

that would fill in and become forest over time. Balancing the plantings of slow growing trees and fast growing trees is a delicate craft. Take the oak tree. They're more like long-term strategists. They're going to grow slower, but they're going to live longer. So the tulips probably will die 100 years. Maybe one of these tulips will fall down or get blown over,

and the oak will take that opportunity to push up, you know, through the next layer. But as temperatures warm in New York City's climate zone shifts, some native trees, such as the sugar maple, are becoming more sparse. Species from the south are creeping in, and native trees that have a large range may become more dominant. For example, tulip tree that we were looking at earlier grows all the way down to do like North Carolina, South Carolina, and beyond.

And also like species like red maple or sweet gum, both native trees of ours, there's red maple in Florida, and sweetcomb grows all the way down to like central Mexico. Species like that will probably play a bigger role. Sucases that we know aren't sort of at the end of their range here. And as for the sugar maple? It's interesting. We're still planting them, but not as much as we used to because I think we're a little worried about their longevity. In an average planting season, Jordan estimates the Alliance plants 300 to 1,000 trees in the woodlands with another 500 to 2,000 shrubs. We think that this area was forested pretty much since the park was created, maybe even before.

The bigger trees have been here the whole time. What's really different is the understory. The Prospect Park Alliance works tirelessly to continue the growth of the woodlands that in parts has existed longer than the city itself. For Science Friday, I'm Clarissa Diaz. Clarissa Diaz is a reporter and designer at New York's WNYC. She produced that story in partnership with John Upton at Climate Central and the Pulitzer Center on Crisis Reporting. Now we're going to talk about the science behind planting an urban forest and how you figure out the benefit of a single tree. Let me introduce my guest.

Dr. David Noak, who you heard in that report, is a senior scientist and leader of the I-Tree team with the Forest Service. We'll talk about what that is a little bit later. He is based in Syracuse, New York. Welcome back to Science Friday. Thanks, Ira. Glad to be here. In terms of trees, New York City is known for Central Park and other parks with lots of trees in one place. You talked about this in the piece, but the idea is thinking about a city in terms of an urban forest. Is this a new way of thinking, David?

It's not necessarily new. Urban forestry, as a profession, has probably been around through the 70s and 80s, starting in that but it's becoming more and more popular now in that we have more and more data over the last 10 or 20 years and we're learning more about what these trees in our cities do. So it's the idea of trying to get an additive effect of trees spread around a city? Correct. There's trees not only in Central Park and where they're concentrated in forest stands, but they're spread out through backyards along streets throughout the whole city of New York and other cities. And these trees provide multiple benefits related to cooler air temperatures,

removing air pollution, affecting water, affecting our human health as we view that. So they have multiple benefits and is a high diversity of different types of species in different locations throughout cities. You know, I think a few city dwellers think about their urban forest as having any other benefit besides a nice place to go eat lunch. Well, that's a common one. People appreciate various things. I think they appreciate that, the view, the aesthetics of the forest.

I think they can understand cooler air temperatures because naturally as the city heats up, we tend to walk in the shade into cooler areas so we can sense those. But there's many other benefits that people may not perceive, such as the air being cleaned and water reductions going down, absorption of UV radiation, changes in sound. So just having these leaves out there, the biology and the chemistry of the leaves and the physics of these elements of nature throughout the city affect our lives in many ways.

Let's talk about how you balance clustering versus spreading trees. Let's say you have 100 trees. How would you plant them the best way in a city? Well, that's an excellent question. It would depend on, first of all, the space that you have. So to get a greater effect per area, be that best to cluster them if you have the space. So temperatures would probably drop more as you put those hundred trees together, so we drop the cooling effect.

But then as 100 trees are limited to just that space that you planted in, so fewer people would probably receive that benefit, but the benefit would be greater at that local scale. On the other side, if you spread those hundred trees out across the landscape, each individual tree will probably have a lesser impact per tree, but more people might receive those lesser impact. So it's a question of if you have the space, clustering together is good for many reasons, but in many cases we don't have the space, so it doesn't diminish the capacity of the forest to provide services, even if they're spread apart. If you plant the trees together, did they sort of help each other out to grow? Well, yes and no. In some ways,

the services, because they're planted together, will tend to get greater temperature reduction, but you also tend to block winds more with the greater conglomerations of trees. But On the other side, if you plant them together, they tend to grow because trees need light and water to grow. If you have trees in a forest stand, they're all competing for that limited resource of light and water. So we tend to have more competition and maybe more mortality in some ways in these forested stands because it's hard for a small tree, a seedling that's established in a forest stand to make

it to maturity because it has to compete with not only animals that might eat it, but all the light and water that it needs to grow, where singular trees and cities have less competition for light and water. and often people water them. So in some ways, they're better off and maybe healthier, in some cases, being an open-grown situations, but often we put them in narrow pits near roadways, which limits rooting space, which cause problems. There can be vandalism, damage to the trees, pollution, so the other factors that could diminish

the health. There are benefits of having trees together, but there's also that tends to be a competitive factor of having that forest stand of the trees next to each other. You know, I know anybody who goes into a stand of trees knows there's a cooling benefit that comes with the trees. And it's more than just shade, right? Yeah, it's definitely more than just shade. A lot of evaporative cooling. So the trees are basically pumping water from the soils and evaporating that to leaf surfaces. And evaporations are cooling process. So what you're feeling two things when you go into the interior of stands or

stand in the shade of a tree, you're getting less radiation hitting you so you're not heating up as much. But also you're getting that evaporative cooling that's blowing from the leaves down to you. So you're getting cooler air temperatures refreshing you as the air passes over you. So if you took out all the trees in a city or a space, you would radically change the urban feeling there. Oh, in so many ways you would. Visually, definitely, you would see a change, and that would have a big impact, I think, on people. But the physical environment would change. Temperatures would go up, wind speeds would go up.

It would become, I just said that, it would become warmer, but it'd be more pollution in the atmosphere because the plants are actually absorbing pollution as it's transpiring that, those gases through the leaf surfaces. it's also taking in air pollution in the gashes and removing it at the leaf surface. So many attributes of the environment would change. Sound acoustics of the environment would change. There's so many ways that, again, we maybe not appreciate all of them, but you'll appreciate it once they're gone. If you're an urban planner or a tree specialist like you are,

how do you decide what tree would work best in what city? Partly it's based on local expertise of experience of knowing what trees will survive. But also, we build a tool called I-Tree. You were trying to help people match up the trees to not only surviving in their area, but what services they provide. When you plant a tree, you want the tree to survive. So you want the right tree in the right space. So big trees do better than small trees, long-lived trees, do better than short-lived trees.

You have to fit it to the space and the conditions of the soil and the environment around that. Like bigger trees, produce more leaves. They're better at removing air pollution. They're better at reducing temperatures. Some store carbon better. so when you design your sites, look at what problems you might be trying to solve and then pick from your palette for which trees do best on that. We have a series of tools and that they can use the tools and do it themselves.

That's the concept of I-Tree to build this data to let people easily collect data and make their own local assessments and their own local decisions. But in the process of doing this, we like working with the cities to learn what they need to do so we can customize these tools to meet their needs. So anyone can download this I-Tree app and figure out the value of their trees? It's for anybody. We try to make it as simple as possible. The My Tree app is a single tree app that works on your phone where you can record where you're at.

You put the tree species and size in it'll tell you the value of that tree at that location. Very simple tools. We design that for homeowners and kids. There's a tool called design where you can sketch your house and put trees around it. So it's very site-specific, but few trees. If you start getting into large number of trees like the city of New York, where we had the sample, anybody could do it, but it tends to be more people that are professionals and managers that want to know about larger systems.

I'm Ira Plato. This is Science Friday from WNYC Studios. We're talking about the urban forest with David Noak, a senior scientist and leader of the eye tree team with the forest service. When you say the value of a tree, what is the metric that you're using to measure the value? In terms of what, what is the value? From the structure of the forest, it's locally. We try to assess what the tree does, the services provided. We'll never know the true value because we'll never be able to assess all of the true values, such as aesthetics is very difficult. What we focus on is pollution removal, changes in water flows and water quality, air temperatures,

carbon storage, effects on building energy use. And many of those we can quantify, like building energy use, if we quantify how many kilowatt hours are being saved due to the evaporative cooling and shading of buildings, we can use local utility costs to determine what the monetary value of that is. For things like air pollution, we look at changes in pollution concentration and how many people in the area, then we use a program from, EPA called BenMAP to look at metrics of how changes in concentration affect human health metrics, such as mortality, asthma, and other things, heart attacks. So we use various methods to try and get at

how it affects people or, say, energy use and then put a dollar value on those services. So you can actually measure how much money a tree saves for a city? Yes and no. Saving energy is a direct saving. Saving like health effects is indirect. The city doesn't directly see that, but people will see that through better human health, lower costs to health care because they won't have me to go to the doctor as much. Some are more direct that you can see out of your pocketbook. Some are more indirect savings. And again, they're all conservative, so there are many things that we haven't been able to quantify yet. Tell me what it's like being a forestry person working in a city or working with cities. What would you want people to know about

their urban forest? I think working in cities is one of the best places to work because the trees have a direct impact on the lives because the trees are very local. We're in more rural forestestand. there are a lot of trees and very few people. In the urban forest, there are a lot of trees and a lot of people. So you have a direct interaction day to day with these trees, and many people love the trees and are attached to trees and just enjoy being in the forest or the attributes of the forest, such as wildlife. So it's exciting to be in cities just because of the interaction with people and their environment around them.

Terrific. Thank you very much for taking time to be with us today. Thanks, Iyer. Much appreciate it. Dr. David Noak is a senior scientist and leader of the eye tree. team with the Forest Service, and he is based in Syracuse, New York. Also, thanks to reporter Clarissa Diaz for bringing us that story. Charles Berkowitz is our director.

Our producers are Alexa Lim, Christy Taylor, Katie Feather, Kathleen Davis, B.J. Leatherman composed our theme music. And if you missed any part of this program, or you'd like to hear it again. Yeah, subscribe to our podcasts or ask your smart speaker to play Science Friday. And on the Science Friday Voxpop app, we have a future segment on nursing homes. And we want to know, have you had a loved one received care in a nursing home? Tell us about your experiences having a loved one receiving care in a nursing home. That's on our Science Friday Voxpop app, wherever you get your apps. Have a great weekend. We'll see you

next week. I'm Irafledo.