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Climate Change & The Impact on Health: It’s Not (Just) the Heat, It’s the…Everything

September 22, 2021

Challenges in areas ranging from education to the environment, gender to governance, health to housing don’t exist in a vacuum. Each month, Abt experts from two disciplines explore ideas for tackling these challenges in our monthly podcast, The Intersect. Sign up for monthly e-mail notifications here. Catch up with previous podcasts here.

The rising heat around the globe is not only deadly in its own right, it creates additional health threats to humans, including increases in diseases spread by insects and animals, and toxins released by algae. Abt’s Claire Lay and Adam Schaefer discuss the many challenges presented by heat on land, sea, and air, and how the “One Health” approach can help.

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    Read the Transcript

    Eric Tischler: Hi and welcome to The Intersect. I'm Eric Tischler. The Intersect tackles complex challenges around the world ranging from improving health and education to assessing the impact of environmental changes. For any given problem. We bring multiple perspectives to the table. We thought it would be enlightening and maybe even fun to pair up colleagues from different disciplines, so they can share their ideas and perhaps spark new thinking about how we solve these challenges.

    Today I'm joined by two of those colleagues, Adam Schaeffer and Claire Lay. Claire studies the past and potential future health impacts of climate change, notably, the effects of increasing heat on morbidity and mortality. Adam focuses on integrating environmental wildlife conservation and clinical epidemiology to protect public health.


    Claire Lay: Thanks.

    Adam Schaefer: Thanks. Hi, Eric.

    Eric: Increasing heat due to climate change is a threat to our entire ecosystem, and the dangers are both far-reaching and varied. Today we’re going to talk about how we can scan multiple fronts to mitigate the impacts. Claire, you’ve been studying the effects of heat on human health. What has your research been showing, and what do you think after this intense summer?

    Claire: Thanks Eric. Yeah, so we did actually just publish a paper called “City-Level Vulnerability to Temperature-Related Mortality in the U.S.” and that included some future projections and was based on looking at mortality data over the last several decades, as it related to temperatures. That paper incorporated climate change data that has already happened up to this point, and it incorporated data that went through I think, 2013. So we had some level of knowledge about both how climate change was and increasing temperatures was going to affect mortality. And also how the things that people do to prevent the effects of heat on their mortality, like adding air conditioning and adding warning systems for high temperatures can really bring down the mortality curve in places that are impacted by high temperatures. That said we published it in June. And I have to say that this summer has really changed the way that I'm looking at some of the higher temperature estimates that we've seen through the model temperature projections. We did not really incorporate any 122 degree temperatures in the Pacific Northwest into that model, you know, so 115, 120 is not in there. So I think that there is some additional estimation to be done.

    Eric: Right. And you were already saying that opportunities to mitigate are shrinking, right? So this isn't helping..

    Claire: Oh yeah. So, again, that research looked at effects of air conditioning in places that have already hit 100 percent air conditioning. And we found that, although it looks like up until 2013 or so, those places were doing a pretty good job of reducing the impacts of increasing daily temperatures. It, one, doesn't account for the speed at which these changes are happening, so you can't get 100 percent air conditioning coverage all that quickly. And, two, in those places where we do have full coverage, they may be running out of options to prevent further mortality and morbidity as a result of warming temperatures.

    Eric: We're all aware of heat; it's getting hotter and we all feel it. But Adam, you've been studying the impacts of heat on human exposure to harmful algal blooms, which may be coming from left field for some people. You want to explain the connection and, and tell people what you're seeing?

    Adam: Yeah. Eric, we're supporting a CDC study on the potential impacts of aerosol exposure to harmful algal bloom toxins. We're primarily focusing on populations in Florida, but harmful algal blooms occur across the United States and they’re a concern globally. And the concern that's related to climate change and heat is the fact that these algal blooms are really dependent on a couple of environmental conditions. First of all, the nutrients in the water, but also temperature plays a major role. So, as we see temperatures increase, we see blooms in areas where we haven't usually seen these algal blooms. And then we see increases in the duration and the intensity of blooms in a harmful algal bloom is really just characterized as an algae that's overgrowing, right? That can continue to grow in a particular area, freshwater or saltwater. And many of these have the potential to produce toxins that are harmful to human health.

    So, for example, a blue-green algae that we're focused on can produce a hepatic toxin. So that's a toxin that targets the liver, but it also can have effects on renal function long-term. And then we see acute effects when individuals are exposed to a variety of algal blooms. So you're seeing, you know, coughing, trouble breathing. And those sorts of effects are really important to study among folks that might have a condition like asthma that makes it more likely that they're going to have potential adverse outcomes after they're exposed. But this is all connected to the health of the environment and the temperature and the changes that we're seeing in the environment can only exacerbate some of these bloom conditions.

    Eric: Right. And you're saying that they're widespread as well, right? So this isn't just, like, if you live by the ocean, you're in trouble.

    Adam: Yeah. Some of these algae will bloom in freshwater systems. For example, the Great Lakes commonly have algal blooms as well. And there's been some examples, again, around the world, even in Brazil, which had a well that was contaminated with a blue-green algae that the water was used for patients that had renal disease. And those patients who are, were exposed actually had a high mortality rate.

    Eric: So, if that's not bad enough, we've got another esoteric front that you both looked at, that's also disease vectors as they relate to heat. And so what are the two of you seeing?

    Claire: I'm originally an ecologist. And, so, my focus has really always been on sort of complex systems. One of the pieces that we did a number of years ago was a research article on the increasing range of Lyme disease. As temperatures become warmer, as some places become more humid, we are definitely seeing that the ticks that are the vector for Lyme disease and and some other tick-borne diseases, they're definitely changing in range. They're showing up in places that we haven't seen them in before. And we can anticipate that kind of spread of vectors like mosquitoes and ticks as a sort of general effect of climate change, that is somewhat difficult to estimate. Adam, I think has done a considerable amount more in this particular of field zoonotic diseases, so things that live in animals and can be transmitted to humans.

    Eric: Yeah. Adam, you want to tell us what you've been looking at, please?

    Adam: Yeah, thanks, Claire and Eric. A lot of my background is in environmental health, including wildlife. And as Claire said, with temperatures increasing the geographic spread of many of these diseases, vectors like mosquitoes continues to expand and we see changes in arboviruses. So mosquito-borne viruses like West Nile and Zika are where we're seeing outbreaks and concern, particularly in south Florida, for example. But we also use wildlife as indicators of some of these potential infectious diseases that occur in areas, again, that are bordering on human populations. And as temperatures change, in some cases, it increases the opportunity for animal species to interact or individuals, humans to be exposed.

    For example, some marine mammal work that I've done where we've seen a mosquito-borne diseases in the animals, but also antibiotic resistance in the microbiology of these animals. And that's a concern as well because we're seeing potential human pathogens that are beginning to show resistance to common antibiotics. The same kind of antibiotics that are usually used to treat humans are actually showing up in bacteria that dolphins are carrying, for example. And you wouldn't expect that because dolphins aren't necessarily taking antibiotics, but because of the environmental conditions and because of contamination into the coastal waterways, we're seeing things like this, where we see again, a potential, if a person, for example uses the same water, right? They eat some of the same fish if they're exposed and they might be immune compromised or have an open wound, they're likely to get an infectious disease. And again, with the environment component here, water temperature plays a major role in the spread of pathogens in aquatic environments as well.

    Eric: So we're looking at land, sea, and air, right? Heat impacting us from every angle. So it's easy to feel overwhelmed. What should we be looking for? What else can we do to sort of help safeguard against these different fronts?

    Claire: So thanks Eric. I would say that there is a considerable amount that we can do with adaptation infrastructure. That kind of infrastructure is really in place for human populations in the south and in many places. Those are things like lean centers and making sure that there is good evacuation planning for big events. Making sure that there's sufficient air conditioning coverage and that the power grid is able to handle high load times. Also focusing on things like upgraded warning systems for days where we're anticipating high heat. Systems for keeping workers safe in the fields, in construction sites, and things like that. And that's the kind of thing that we can do for the human population.

    I'd also say that the kind of work that Adam is doing that focuses really heavily on environmental effects in the complex network is really important. We don't just have warming, we have warming plus contamination of waters, plus a slew of other things like high particulate matter that can all interact together to produce some kind of unexpected effects, so one big thing, and identifying those kinds of network effects is going to be finding good indicators that we can use to sort of early warning systems so that we can both respond to issues that are coming our way and also change our behaviors so that we can ensure continued ability to live in particular places and things like that.

    Eric: Claire, you mentioned evacuation, is that what you call it when people move to cooling centers or you're referring to other events?

    Claire: I'm speaking more evacuation routes for things--like we also do planning for hospitals and nursing homes that are faced with hurricanes and other large weather events. So evacuation planning is a really important way that we can limit some of the mortality and morbidity events that might be fairly large.

    Eric: And you're referring to those events increasing, due to heat? Okay. Thank you. Adam you want to talk about your work with systems?

    Adam: Yeah. So the, the complex problems and potential routes of exposure that Claire was talking about really require complex solutions and determining the best indicators, whether it's a particular environmental indicator or wildlife sentinel all really need a very, very specific and integrated surveillance networks and -

    Eric: And I'm sorry, by sentinel you mean that you're using sort of the, these animals to help us to indicate health issues

    Claire: A warning system of other species that might be impacted. Yeah.?

    Adam: So in essence, we're using some of these animals as a canary in the coal mine, right? To send us an alert of potential changes in infectious diseases and environmental exposures.

    Eric: Thank you. Perfect.

    Adam: And that information obviously can be very valuable in terms of taking public health action. But in order to do that, we need to connect data sets. As we said, these are very complex systems and interactions. So for example, with a harmful algal bloom work, we're connecting environmental sampling.--so water sampling with air sampling--all timing it, and geographically locating it with the human exposures that we're looking at and that we're concerned about. But to do this on a wider scale for a variety of diseases and exposures, we need integrative surveillance that uses what we commonly refer to as the One Health approach. So that's where you're pulling in teams of individuals from physicians, veterinarians, ecologist, biologists, all working together to build a network of data that's going to be able to inform us and really look at the big picture. And those sorts of integrated data sets can then be tied into weather datasets. And really we can look at the effects of changes in temperature and weather patterns on not just environmental health, but also human health and that entire system.

    Eric: Great. So what are some ways we might help bolster that system or some things we can do to help bring it together?

    Adam: These systems really require a lot of communication and collaboration across disciplines, and having teams that are able to manage these very large and complex data sets to be able to perform the kinds of analysis that we need to get these big-picture answers. But we need not just a local effort, but a global effort and commitment to being able to connect these dots and provide early warning for, you know, potential pandemics. When we're looking at some of these zoonotic diseases and the potential of transferring to humans, we need early warning systems that can prevent these sorts of global events.

    Eric: Thank you, Claire anything from your perspective that you'd want to add to that?

    Claire: I guess I would say that the focus on sort of the overarching view is extremely helpful in finding where we should be paying attention, where we should be using particular species as leading indicators of when a risk is coming our way. I would also say that the local scale is really important. The people who are going to be implementing the mitigation measures are going to be working at the local scale. They need to be thinking about their cooling plans and their heat warning plans and their evacuation routes in case of wildfire, flood, or any of the other events that we're facing. And that really does have a finer point on it than it might've had in, say, the eighties. So the, the big picture is really great for giving us ideas where we should look and a small picture is really important for being able to actually do anything about it.

    Eric: That's a great distinction. Claire, do you want to say a little more about the potential discrepancies between the big picture and little picture?

    Claire: So one of the things that we're working on right now is that a lot of the big climate models that are giving us projections of what our future might look like. They're very complex. They take quite a long time to run on the order of days or longer. They're gridded very finely so that they can get a fine geographic scale of prediction. And any one of the models has a tendency to have something in the assumptions behind it that can throw things off a little bit. So the historical approach for handling that has been to average a bunch of those models together. One of the things that happens when we average a bunch of models together is that we miss out on some of those really high-end projections, like the potential for a really extreme heat event in the Pacific Northwest.

    Now, I don't know for sure that one of the large climate models would have projected that, but I do know that by averaging all of the different estimates for a number of different models together, we're definitely damping down those, our interpretation and our assessment about the future for those more extreme events. So one of the things that we're doing is we're working on a suite of models that run rapidly because they're much more simple. And we're working on this with a number of collaborators, including the EPA, to run really fast assumption checks to see what happens if we have the sea ice go in much faster than it's generally anticipated, or we have some key, very large fire that can produce shade for a short period of time. So those kinds of rapid models might give us a better picture of the high end difficulties that we may be facing in particular areas. But open questions, still.

    Eric: Thank you. So threat from land, sea, and air. We need global and local solutions and data. That's a lot, but I think it's great that we're taking a holistic view to what is a holistic problem. And so, so thank you both for sharing those multiple corners of the issue that, that the two of you are working in.

    Claire: Yeah, of course. Thanks for having us.

    Adam: Thank you.

    Eric: And thank you for joining us at The Intersect.

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