Welcome to the big idea of Planetary Health. Planetary Health is a new topic, and scientists and other researchers around the world are studying it just the way you might study biology or math or other subjects. The subject of Planetary health focuses on understanding the impact of environmental changes on human health.
As you might guess from that sentence, there are two big parts of the idea of planetary health: Environmental changes, which include different types of large-scale changes to our environment—often caused by humans; and health impacts, which are the different types of effects that these environmental changes can have on human health. This document tells you about three topics in each of these categories. Let’s start with environmental change.
One big environmental change concerns changes in how people around the world use land. In other words, changes in land use. Land use changes when natural habitats are converted to other uses. For example, urbanization is a change in land use. Urbanization means the spread of big cities. As more and more people are living in cities around the world and cities are growing larger, ecosystems are changing. Forests are cut down, wetlands are drained, coastlines are altered. A similar thing happens with the spread of big industrial farming, which is also a change in land use. Big farms convert large areas of natural habitat into huge fields, sometimes just to a grow single crop, like corn or soy beans. When this happens, it changes the ecosystem for the plants and animals that used to live there, especially for the bees and other insects, birds, and bats needed to pollinate the crops. When the pollinators lose their habitats, it eventually hurts the crops. It’s important to point out that ecosystem change doesn’t always need to be negative. For example, special bushes can be planted in between rows of crops to create habitats that attract pollinators. Cities can be designed to protect coastlines and to keep pathways of green space that allow plants and animals to thrive.
A second type of environmental change is something that, unfortunately, many of us are familiar with—pollution. Pollution happens when things like chemicals and smoke and trash enter the environment in amounts that harm the quality of the air we breathe, the water we drink, or the land on which we grow our food. Air pollution leads to a variety of types of heart and lung diseases; water pollution affects drinking water and can cause infections and other health problems. Land pollution can cause the food that grows on it to be unhealthy.
Sometimes the health effects of pollution can be indirect and hard to see. For example, there are island communities in different parts of the world where, for generations, people have traditionally depended on fishing for their food. But recently, ocean pollution has decreased the fish supply, so now there aren’t enough fish for everyone on the island to eat. Healthy alternative foods can be very expensive—because it can be expensive to ship food to small islands—so people turn to less healthy foods, which leads to people possibly getting diabetes or other diet-related diseases. But again, it is important to point out that there are positive environmental changes we can make that can help. For example, by changing the way we collect seafood and catching only what we need, we can allow fish populations to recover. This will make for much larger fish populations that can provide food to more people.
A third type of environmental change is changes in biodiversity. Biodiversity has to do with the variety of plant and animal life in a particular habitat or ecosystem. For example, the biodiversity in a forest ecosystem includes all the different plants and animals in the forest and the many ways they interact and depend on one another. When there is a lot of biodiversity in an ecosystem—that is, when there are lots of different plants and animals living together—it keeps ecosystems healthy. When big changes happen to the ways plants and animals interact, for example, when many species go locally extinct, or when invasive species start to take over—the entire ecosystem can get weaker.
Remember: The big idea of planetary health has two parts to it—environmental changes, and health impacts. So far, we have been talking about one side of the idea—environmental changes. We have talked about changes in land use, pollution, and changes in biodiversity. Now we will turn to the other side of the idea and describe three kinds of health impacts. Health impacts are the effects of environmental change on human health.
One obvious health impact is disease. There are lots of diseases that can be caused, or made worse, by changes in the environment. For example, diseases like malaria, and the ‘flu,’ are infections caused by mosquitoes and tiny germs that can be spread from one person to another. Changes in the environment, including changes in temperature, the wetness of soil, changes in rainfall, and in how many trees are cut down, can change how diseases spread and who gets sick. For instance, some mosquitoes that cause malaria really like sunlight, so cutting down trees will make malaria spread because the sunlight can reach into the forest because of the cut trees.
A second kind of health impact is nutrition, which has to do with the food we eat and how healthy it is for our bodies. Remember when we told you about the island communities and the fish? That’s an example of a nutrition-related health impact, because without enough fish—which are very nutritious—people in these communities are often forced to eat foods that are much less nutritious. Sometimes environmental changes can actually change the nutritional value of healthy foods, making foods that were once good for us less good. For example, rising levels of carbon dioxide in the air from factories and cars are making crops such as rice and wheat less nutritious than they used to be. People who depend on these foods may get less protein and fewer of the vitamins and minerals they need, which can lead to various kinds of health problems.
The last kind of health impact we want to talk to you about is mental health. Our minds need to be healthy as much as our bodies do, and changes in the environment can affect people’s moods, their emotions, and their outlook on life. For example, natural disasters like extreme storms, fires, floods, heat waves, and droughts happen more frequently because of climate change, and research shows that these events can cause severe mental stress, anxiety and depression. Even without these extreme events, environmental changes like building more cities and cutting down forests can limit our access to the outdoors, natural sunlight and green spaces, which in turn can have negative effects on our mental health. Of course, cities can also be designed thoughtfully, so that people have lots of access to urban green space like parks and gardens. And when they are, research shows that these increases in green space can make us happier and less depressed.
Well, there you have it. This article has introduced the big idea of planetary health by talking a little bit about its two sides: environmental changes, and human health. If you are thinking that planetary health is a pretty big topic, you’re right: There’s a lot more to learn about it, and we should all keep trying to learn as much as we can. Why? Because the most important point about planetary health is that planetary health is in our hands. Human beings can change the planet—for worse, but also for better. We believe that together, we can all learn more about the connections between environmental changes and human health, so that we can all come up with ideas about how to make the planet, and ourselves, healthier in the future.