Why does climate change matter?


Weather impacts




Ice sheets and glaciology


Rising sea levels


Ocean acidification


Algae blooms


Species extinction


Human health


Food security


Economic impacts


Climate change vs. equity




Intro to climate change


Why does climate change matter?












What can we do?

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Why does climate change matter?

We've just discussed the basics of climate change. So--who cares? Let's review and jump into the impacts that connect you to climate change.

Weather impacts

Extreme weather

What evidence do we have that climate change is impacting extreme weather? Let's watch this next video to learn about attribution science.

So while we can’t say for certain that an individual storm was caused by climate change, we can say that climate change made the storm more likely to occur or perhaps more severe. We can also blame climate change for a general trend of longer storm seasons, more storms, and greater severity. If you want to better understand these probabilities, watch this optional video about hundred-year floods (it has some cool dice!). But of course, hurricanes aren’t the only kind of extreme weather that will be affected by climate change. Let’s talk about what changes we expect to see, why, and how we might be able to adapt.

Heatwaves: when the Earth gets warmer, it makes sense that we’ll experience that warmer world, though it’s not as simple as the daily temperature being a few degrees warmer every day. One of the effects we will see is that heat waves (periods of intense heat) will be more frequent, more severe, and longer-lasting. “The National Climate Assessment estimates 20-30 more days over 90 degrees F in most areas by mid-century. A recent study projects that the annual number of days with a heat index above 100 degrees F will double, and days with a heat index above 105degrees F will triple, nationwide, when compared to the end of the 20th century” (source). Heatwaves are deadly because they not only cause heat stroke, but they can also exacerbate health conditions like asthma, kidney disease, and insomnia. Resilience methods include cooling centers and more efficient power grids for handling the increased load of air conditioning, as well as green roofs, cool pavement, and increased tree cover in cities to keep them cool.

Drought: as water evaporates faster in warmer temperatures, increased droughts are one of the most important consequences of climate change. The heat can also disrupt wind patterns that usually bring a region rain, and it can decimate the snowpacks that feed rivers in the first place, introducing drought to areas where it was never a problem before. Droughts hurt people all over the world through water shortages as well as crop failures and famines that increase global food insecurity, but we can do our best to address these through better water management and less water-intensive agriculture.

Wildfires: wildfires go hand in hand with high temperatures and drought-withered plants, both of which are exacerbated by climate change. Between more fire-prone conditions and a longer fire season, “For much of the U.S. West, projections show that an average annual 1 degree C temperature increase would increase the median burned area per year as much as 600 percent in some types of forests” (source), worsening the destruction and tragedy that we already observe today. We can try to cope through better forest management (such as controlled burns to clear fuel), more fire-resistant design in where and how we build our houses, and spending more resources on firefighting and prevention.

Extreme precipitation: If it’s true that climate change causes droughts, how can it be true that it also causes flooding and other extreme precipitation events too? Well, when all that water evaporates from areas in droughts, it doesn’t disappear. Instead, it sticks around in the air, which is now warmer and can hold more water. And when all that extra water comes down, it causes flooding, devastation, and loss of life. To make matters worse, because it now comes down in occasional larger storms instead of more frequent smaller storms, the soil gets saturated and the excess water drains away before the community can benefit from it. Thus, even areas that experience extreme precipitation can still suffer from droughts. Resilience methods include water management systems to slow the damage and capture rainfall. You’ll learn more about this “green infrastructure” in a later section.

Hurricanes: Increased precipitation under climate change will also mean increased rainfall from hurricanes. But hurricanes won’t just grow more intense due to heavier rainfall. Heat is the energy that drives hurricanes, so a warmer Earth means higher wind speeds, longer hurricane season, and wider areas vulnerable to hurricanes. Any given storm is likely to be stronger, and what might have been just a tropical depression is more likely to be a full-fledged hurricane. They’re also likely to move more slowly and thus dump more rain over an affected area. Lastly, higher sea levels make storm surges more severe. The best ways to adapt include elevating buildings and preparing with boarded windows when storms approach, as well as constructing storm buffers like wetlands and seawalls to absorb storm surges.

Blizzards: This is perhaps the most counterintuitive effect of climate change, but as warmer air contains more water, that means that when the air does cool, it has a lot more snow to dump. And although average temperatures might be going up, cold weather isn’t going away any time soon. Resilience methods for blizzards include emergency stores of non-perishable goods, sturdy roofs, and burying power lines to prevent outages from icefalls.

It’s also important to remember that for all of these disasters, members of marginalized communities are likely to be disproportionately harmed. We’ll talk more about this soon, but those in poverty don’t have the money to move out of vulnerable areas, rebuild after a disaster, or fund resilience efforts. In addition, as has been demonstrated by past catastrophes like Hurricanes Katrina and Maria, our government often doesn’t provide timely or adequate disaster relief to communities of color.

These extreme weather events ravage the news, too. Let's read through this article from Inside Climate News to learn about a disturbing current event from the time of writing this course.

Q: What's on the news right now? Find a recent event (news article, broadcast video, research paper, etc.) that might have occurred because of or been worsened by climate change and summarize below.

Everyday weather

But what about the weather that’s not extreme, the kind we see from day to day? Climate change impacts that, too, of course. Average global temperatures will rise. But that doesn’t mean that the weather will get warmer everywhere. Let’s learn about some of the important processes climate change might disrupt.

Watch this video to learn about the jet stream disruption.

Next, let's watch this video about Gulf stream disruption. Alternatively, you can read this article. Despite their similar names, Gulf stream disruption is unrelated to jet stream disruption!

Q: How are the disruptions of the jet stream and the Gulf stream similar? How are they different? Consider their causes, behaviors, and effects.

Water shortages

Are you wondering how increased rain and increased drought can coexist? This next video is a good introduction to how climate change can cause water shortages. A deeper dive can be found in this optional video.

Remember that bit about migration and war that came up in the first video—it resurfaces in later sections in the course, influencing food security, health, and equity.

Q: Review and reflect. How will climate change likely affect weather in your region? Consider both everyday weather and extreme weather events. How should your community adapt in the face of these changes?


Our planet’s forests are some of the most valuable resources we have. They provide us with clean air, construction material, food, and more. Even more importantly, they are one of the most important defenses against climate change!

Who cares if we cut down all the trees? Sure, it sounds like a bad idea, but what would really happen to a city without trees? Let's watch this TED-Ed video to find out.

Habitat loss and fragmentation

If you ever thought that deforestation is unrelated to your current lives, let’s take a look at how deforestation played a role in causing pandemics and epidemics that have changed the course of society.

Covid-19, SARS, and Ebola are three highly infectious diseases that plague the human species since 2002, and all three leaped to humans from wild animals that lived in dense tropical forests. As we slash and burn the forest habitat to create land for agriculture, the chances of us coming in contact with wildlife that carries infectious microbes increases. Watch this animated video from one of our team members to learn more.

The occurrence of Covid-19 is catastrophic; however, this can pivot our attention to the consequences of exploiting our natural world, as well as the huge payoff we can achieve once we change our actions.


Although wildfires are natural occurrences within some forest ecosystems, fire seasons are becoming increasingly more extreme and widespread. The continuously hot and dry weather caused by climate change creates favorable conditions for more frequent and higher intensity wildfires. Fires, either ignited by humans or lightning, are much more likely to burn over larger areas and at hotter temperatures with drier conditions. Forests degraded by logging and disease, and fragmented by deforestation are also more susceptible to fire (source).

Rainforests like the Amazon are especially affected. You may recall seeing videos last year of the Amazon burning; though our attention may have moved elsewhere, the situation has not improved. It is estimated that 2020 was an even more devastating year for the Amazon as well as the indigenous people who call it home. Let's watch this next video to learn a little more about what the Amazon forest first can tell us about deforestation.

Wildfires release pollutants such as carbon dioxide into the atmosphere, exacerbating global warming, and irreparably damaging forest ecosystems where more than half the world's land-based plants and animals live. In addition, the resulting smoke and other emissions containing pollutants can travel long distances, creating significant public health crises. Uncontrolled wildfires also cause billions of dollars in economic damage each year as property and natural tourist attractions are destroyed and economies are crippled by evacuations (source).

Let's visit the Global Forest Watch and examine recent trends in fire alerts. Pick a region to investigate!

Q: What did you learn about your region? Are there trends that you can pick out? Where are the forests located? How does your location stack up with other areas?

Ice sheets and glaciology

There’s a lot of ice in our poles, and it’s melting fast. But how much would the melt really affect us? Just how much water is held in the ice caps? Watch this quick video as an intro to this segment on how climate change affects our cryosphere.

So, that's what would happen if all the ice were to melt. But with the climate change we are predicting, just how much ice do we expect to melt? Let's check out this article from NASA about the long-term sea level rise from melting ice in Greenland.

There are two main types of ice: ice that forms in the ocean, or sea ice, and ice that forms on land, such as glaciers, icebergs, ice sheets, etc. Sea ice impacts climate in two main ways: reflecting sunlight back into space, and changing the surrounding salt concentration when it forms.

If emissions stabilize by the end of the century, based on IceBridge’s glacial mass model we lose 26-57% of the total mass currently. However, if they continue to increase, we could lose up to 99% of glacial mass by 3000. If they decrease, we can limit the losses to only 8-25% - still a large number, but much more manageable.

Q: Why is sea ice important? What effect will climate change have on it?

NASA has put together a few articles that describe major factors that impact sea level. Let's first take a look at the tabs under Global Sea Level.

Now take a look at the tabs under Regional Sea Level.

Q: How do they compare to Global Sea Level? Do you see one as more important?

Lastly, take a look at the By The Numbers and the Key Indicators tab. By The Numbers provides a nice numerical breakdown of the changes happening, and the Key Indicators provides a more graphical view.

Current events in the cryosphere

The cryosphere is the part of the earth's surface characterized by the presence of frozen water. The Larsen Ice Shelf is a long shelf on the east coast of the Antarctic Peninsula, commonly divided into four segments: A, B, C, and D. Let's read about some major melts.

Q: Consider why their breakaways are significant to the overall landmass. Do you think these melts were caused by climate change? How will they affect the future of the cryosphere?

Next, let's check out the Global Ice Viewer from NASA to explore the ablation data and pictures.

Look at the ice flow map under the Antarctic tab. Pick an area of fast flow, and look at a map of the ice shelves in the corresponding area.

Q: How would you describe the connection between flow and ice shelves?

Optionally, pick a shelf to research and look into whether the shelf is still stable today.

Bonus for the glacially inclined

Check out this photo glossary of glacial features!

The following video shows both the speed of the ice sheets and gives a more understandable look at what exposing bedrock will look like as the massive ice sheets covering Greenland give way. If you’re interested in IceBridge, here’s more on its history.

The Greenland Ice Sheet lost 3.8 trillion tons of ice between 1992 and 2018. Based on this, it will contribute to a gain of 3-5 inches in sea level by 2100.

The Greenland Ice Sheet is one of two ice sheets left in the world: the other is the Antarctic Ice Sheet. Here's another article from Nasa that dives into Greenland's melt.

If you are interested, the third ice sheet that existed up until 20,000 years ago was the Laurentide Ice Sheet. It covered most of northern North America (i.e. Canada and the northern US), advancing and retreating multiple times during the Quaternary glacial epochs.

Rising sea levels

So where is all that ice going? Well… into the ocean. Not only that, but as the ocean warms, the volume of water itself increases. This thermal expansion is predicted to account for about 75% of future sea level rise. Read this article to learn more about how water is affected by climate change.

Q: Why does melting ice cause more warming?

Let's read the following article from National Geographic, which encompasses the many impacts of sea level rise, including loss of habitat, erosion, flooding, and more.

Q: What are some ways communities are adapting to the extreme weather and rising sea levels?

Next, let's watch this video from Our Changing Climate, which explains nuisance flooding and provides a nice visualization of the data trends.

Many cities are at risk, especially ones near the coast. Let's visit Google Earth's models of sea level rise in prominent cities at different temperature levels.

Q: What did you notice from the Google Earth videos? What surprised you? Which temperature increase would you rather experience?


So what? The oceans are rising. I’m not on the coast. Why should I care?

Well, as it turns out, a lot of infrastructure is at risk. The interconnected nature of American infrastructure for key systems like the internet means that just one foot of sea level rise could plunge 20% of America’s internet infrastructure under water, due to its concentration in coastal cities like New York and Miami.

Costs for rebuilding and protecting this infrastructure won’t be cheap. Even the cabling built to be water resistant will likely not survive being permanently submerged. These internet disruptions won’t just affect jobs and businesses, but could throw off everything from traffic lights to flight patterns, which are now online. If you’re interested in learning more about the internet and climate change, you can read this optional source.

Another form of infrastructure that will be affected is the power grid. Nuclear plants need a constant supply of water to maintain their cooling systems, and many draw this water from the ocean. Depending on where you draw the line, between 25 and 40% of power plants are located along the coasts, with this figure potentially rising as high as 66% among new plants.

Rising sea levels increase the likelihood of floods and tsunamis that, in the best-case scenario, will temporarily shut down a plant’s power operations and, in the worst-case scenario, can cause meltdowns and other nuclear disasters. As sea levels only continue to rise, we will be forced to remove nuclear materials from flooding sites. Even if we can safely move these radioactive materials and avoid meltdowns, this still leaves us only more dependent on fossil fuels to provide energy. For more information on nuclear power and climate change, you can read this optional source.

Q: Can you think of any other potential effects of rising sea levels? If you can’t think of any new ones, consider other potential consequences of the effects discussed above.

Ocean acidification

Let’s start off with a short review. Remember when you learned what the carbon cycle is? It’s the movement of carbon between the air, land, and water, as a result of plants using carbon during photosynthesis to grow and living things making carbon during respiration to make energy.

Usually, this cycle keeps the levels of carbon steady in the air, the water, and in plants. But since the burning of fossil fuels and the cutting down of forests started, more and more carbon dioxide (CO2) is being pumped into the atmosphere. What do you think this does to the ocean? Do you think that having more carbon dioxide in the air can have large repercussions for the fish in the ocean? How do you think that happens? Make a prediction for yourself.

The change in the ocean’s pH over time.

The change in the ocean’s pH over time.

Before we talk about how organisms in the ocean are affected by changes in the carbon cycle, we need to talk about how the ocean water is affected. In the picture above, the line is tracking changes in something called “oceanic pH.” This is the measure of how acidic or alkaline the ocean water is. The acidity is inversely related to the concentration of hydrogen ions in the water. In the water, these are individual atoms of the first element in the periodic table, hydrogen that have lost their only electron.

The periodic table with hydrogen emphasized.

Hydrogen, image from knowledgedoor.com

The hydrogen atom on the left and the hydrogen ion on the right (with the electron missing).

Image from Ions and Chemical Bonding

The “inverse relationship” means that as the number of hydrogen ions increases, the pH decreases. pH is unitless but has a logarithmic scale from 0 to 14, with pure water in the middle with a neutral pH of 7. “Logarithmic” means that with each step up or down the scale, the concentration of hydrogen ions changes by a factor of 10. So, if you have a cup of water with a pH of 7, another cup of water with a pH of 6 will be 10 times as acidic, and a cup of liquid with a pH of 5 is 100 times as acidic.

The smaller the numbers get on the scale, the more acidic the substance is, like vinegar or lemon juice. The higher up you go, the more alkaline the substance, like baking soda or bleach. Seawater is naturally more alkaline, with a pH around 8.16. As we can see from the graphic, over time, the oceanic pH has become more acidic, meaning the pH is getting smaller and smaller.

The pH Scale

Measuring Changes in Ocean pH, image from the NOAA Ocean Acidification site.

But what does this have to do with the carbon cycle? While the amount of carbon dioxide in the atmosphere is increasing, the ocean’s pH is decreasing instead. But the ocean’s pH depends on the amount of CO2 in the ocean, and this ultimately is affected by the amount of CO2 in the atmosphere. To understand this, we’re going to look at some data from this online activity by NOAA on ocean acidification. Take a look at the following graph of measurements scientists have taken in Hawaii since the 1960s. Make sure to look at the legend so you understand what the graph says.

Graph of atmospheric CO2, ocean CO2, and ocean pH over time in Hawaii

Graph of atmospheric CO2, ocean CO2, and ocean pH over time in Hawaii

Q: Pick the right conclusions to make about this graph.

  1. On this graph, the red line shows an [increase / decrease] in atmospheric CO2 over time.
  2. The atmospheric and oceanic CO2 follow [the same / different] trends over time.
  3. As the atmospheric CO2 changes, the oceanic pH follows [the same / a different] trend.

Here, we see that as more carbon dioxide is present in the atmosphere, the ocean becomes more acidic. This means the pH is decreasing, and the concentration of hydrogen ions is increasing. We can see these changes over time at this next website by NOAA.

Click the link and find the slider that shows the change over time. Notice that the animation starts in 1861. What color are most of the oceans when you first open the website? Move the slider to the year 2030, then to 2070. What change have you noticed? Finally, move the slider all the way to the right to the year 2100. What color is almost missing now?

The dark blue at the beginning around the 1800s meant the ocean around then was mostly basic, with a pH around 8. However, by the year 2100, almost all the oceans have a pH of 7.7. So, how does the ocean being more acidic affect the animals living there? Watch this video by the Alliance for Climate Education, which explains the impact of ocean acidification.

One mineral that shell-building animals need is aragonite. But as the ocean becomes more acidic, it’s harder and harder for these animals to find aragonite to make their shells big and strong. We can see trends in how saturated aragonite is in seawater and make predictions for how saturated it will be in the future with another NOAA visualizer.

Q: When you first open the site, what color is the ocean mainly? What does this mean? When you move the slider to some time between 2020 and 2030, what changes have you noticed? When you move the slider all the way to the right to the year 2100, what color is almost gone now? What color do you see more now? What does that mean for the animals that require aragonite to make their shells?

Here, we can see that the more acidic oceans are, the harder it is for animals to survive—and, as the video stated, if the oceans are acidic enough, their shells will begin to dissolve in the acidic oceans instead of growing stronger. This makes it harder for fish that eat these shelled animals to find food, which makes it harder for people who rely on these fish for their livelihoods to survive.

One example of an animal crucial to the survival of marine animals and the people that depend on them to buy food to put on the table is the humble coral reef. These reefs may look like pretty rocks, but in reality, they are living organisms that support 25% of all marine organisms. They use chemicals in the water to grow larger and make more habitats for other fish. However, when the water is more acidic, it is harder for them to grow, threatening the populations of countless fish and the livelihoods of millions of people who rely on them. Many other factors, like warming ocean temperatures, overfishing, and ocean pollution are threatening these corals, so adding on ocean acidification is not helping conservation efforts. If you are interested in learning more about coral reefs, the threats they face, and their importance to the ocean ecosystem, check out this article by CarbonBrief.

Algae blooms

You’ve already learned about a lot of negative impacts of climate change. Here’s another: algae blooms. To learn a bit more about algae blooms, watch this video from the Environmental Working Group. When watching, it may be helpful to create a two-column chart to sort information about how algae blooms form and what the consequences are.

Before you go on to learn about species extinction, let’s review what was discussed in the video. Harmful algae blooms occur when colonies of algae and cyanobacteria grow out of control. When this happens, harmful toxins that hurt fish, humans, animals, and the entire system are produced. As the algae decay, they take in oxygen from the surrounding water, discolor the water, and can get into drinking water.

How does this relate to climate change? We have seen that increased nitrogen and phosphorus in the water leads to more blooms, much of it coming from fertilizers and agricultural products. We are also seeing that increased rainfall and higher temperatures are making these blooms start earlier in the season and last longer. Human actions are directly making harmful algae blooms longer and severe, which will have profound ripple effects on water ecosystems.

Species extinction

You’ve read a lot about how climate change affects ecosystems - acidifying oceans, melting glaciers, burning forests, and so on. To add onto that, we must remember the effects this has on the species that rely on those ecosystems. How do shell building animals adjust to decreasing levels of calcium carbonate caused by ocean acidification? Let’s take a look at the impacts of climate change on biodiversity, diseases, and animals as a whole.

Migrating species and extinction

First, let’s learn about how animals and plants need to adapt to a changing climate. Check out this video from Ted-Ed about how some species are changing, whether those changes are permanent, and how humans can assist.

The video describes a distinction between plastic (non inheritable) and genetic (inheritable) changes. The plastic changes mentioned are things like: changing size, mating time, location, and flowering time. Unfortunately, these changes are not passed onto offspring. On the other hand, scientists have seen some genetic changes, such as the tawny owl changing from white to brown or the Two Spot Ladybug changing from a mix of melanic (black with red spots) and non melanic (red with black spots) to mostly non melanic.

Q: Which genetic (heritable) change did you find the most interesting? Briefly describe the change and why it is advantageous.

Human health

Climate and weather have always played vital roles in human health. Climate influences the flora and fauna (plants and animals) that grow around us and provide sustenance; it determines the way in which we interact with our fellow creatures; and of course, humans thrive in a relatively small set of temperatures that we are lucky to currently experience here on Earth.

Heat-related disease

Cardiovascular diseases (disorders of the heart and blood vessels) are the #1 cause of death globally. As temperatures increase, how do you think the incidence and severity of cardiovascular disease might change? Would it change much?

Q: Briefly predict what might happen and why that might be the case.

Now take a look at this case study published in the Iranian Journal of Public Health. What did they conclude about the relationship between climate change and higher temperatures (at least past a certain point)? Tip: You don’t have to read the body of the paper to figure this out. If this can be generalized, what are the implications for the future?

Q: What kinds of adaptations and innovations would we need to combat increased cardiovascular disease, at the root or otherwise? This is a pretty big question, so feel free to get creative. Anything goes!

Q: What are other examples of conditions you can think of that might be worsened by climate change? Try thinking about how you feel after an exercise session on a hot day.

After you’ve pondered that for a minute or two, briefly check out the following article.

Humidity describes the amount of water vapor in the air. Have you ever noticed the "feels like" section on your weather app? While the app says it'll be 76 degrees one day, it also says that it'll feel like 85 degrees instead. This isn't a mistake! High humidity creates a stickier, sweatier environment, making it seem hotter than it really is. The heat index is a more accurate representation of how the weather might feel to us, taking both relative humidity and temperature into account.

Heat index

Let's watch this next video from the YEARS Project, which explains how humidity makes the heat more deadly.

Think about how you would illustrate the disparate effects of climate change on different types of people.

Q: Imagine how increasing temperature and humidity will affect you and your community. Now consider how it might affect a community in the developing world. What might be different?

Air pollution-related disease

Have you ever thought about how climate change can affect the air you breathe?

Q: Make a prediction: What actions aggravate climate change that might also affect air quality?

In fact, when climate change causes more wildfires or when more forests are cleared for agriculture, more smoke enters the atmosphere. This increases the concentration of tiny particulates in the air. These particles can aggravate many respiratory health problems, like asthma, by irritating your eyes, nose, throat, and lungs. Over time, repeated exposure to high concentrations can cause other health issues like heart disease, lung cancer, chronic bronchitis, and more. This is yet another example of how climate change can have negative impacts on human health.

Now, take a look at this interactive from the New York Times that compares the city with the world’s worst air pollution to your city. If you can access the interactive, answer the following questions. If you can’t access the interactive, a few graphics from the interactive are below using Washington, D.C. as an example. If you want to answer the questions, try finding the answers online.

Q: What was the pollution in your city on the worst air quality day of the year? What level would it be considered?

Q: In which city was the most recent air quality crisis? How concentrated were the PM 2.5 particles? Is this even within the EPA’s air quality categorization scale?

Q: What are some events in China or in Brazil that caused high PM 2.5 pollution during 2019?

Beijing also used to be plagued by poor air quality, but since 2014 actions have been taken to improve the air, such as setting limits on burning coal, new emissions standards for sources of air pollutants like power plants, and banning the building of new power plants while shutting down the oldest ones. It has also restricted the number of vehicles present on the road at any time and supported the use of electric buses that don’t create large amounts of air polluting particles.

Q: What are some actions that you can take to help lower air pollution?

Disease outbreaks

In addition to heat- and air pollution-related deaths and injuries, climate change has the potential to increase the frequency and severity of disease outbreaks. Climate change can increase the risks of diseases carried by tickets, rodents, fleas, and mosquitoes. Hotter temperatures increase the rate of spread and allow the pests to carry and spread diseases for longer portions of the year. Read this article from The New York Times about how the spread of dengue fever may worsen, and watch this video from the YEARS Project to learn about how climate change affects ticks:

Q: What did you learn about how climate change may worsen the spread of dengue fever and lyme disease? How do you think climate change will worsen the spread of other diseases based on what you learned?

Flooding and Storms

As mentioned in previous sections, climate change will increase extreme weather events like flooding from intense storms. Besides the effects discussed in those sections, flooding will impact human health as well. Flood waters can contaminate food and water sources, spread dangerous bacteria and viruses, and cause difficulty in reaching health services.

Read this document from the CDC which discusses the dangers of warming waters and increasing numbers of floods:

Read this article from the National Resources Defense Council (NRDC). Skim the first few sections to get a refresher on the impact climate change has on storms and flooding and focus on the “Flood Consequences section.”

Q: What is the link between climate change and waterborne disease? How might flooding impact some communities more than others?

Food security

Food security is when all people at all times have physical, economic, and social access to sufficient, safe, and nutritious food to lead active and healthy lives (source). If you’d like to learn more, watch the following optional video from the World Economic Forum.

Reflect on all the other impacts of climate change you have learned about so far. Brainstorm ways that this might affect the production and distribution of food, particularly for people who are at the greatest risk of food insecurity. Then read this article from Columbia University's Earth Institute, which explains the impact of climate change on agriculture.

You can also read this optional article, which includes potential solutions to these issues.

Q: Which impacts in the article(s) did you anticipate? Which were new to you? Did you have any ideas that the article did not discuss?

Economic impacts

Perhaps one of the most frustrating responses to fighting climate change is the argument that “reducing emissions would require disrupting the economy.” But it’s important to remember that climate change will deeply affect just about every aspect of our lives. And that, of course, includes the economy.

Surely, compared to all the other impacts we’ve gone over so far, the economy should be the least of our worries, you might say. But remember that during recessions, people lose their jobs and healthcare, small businesses struggle, and the impoverished suffer. When the stock market falls, people lose their retirement savings. And while preventing climate change may cause some damage, the economic and human suffering that it will bring far outweighs the sacrifices involved in preventing it.

Studies find that the impacts of climate change could cost the economy at least $150 trillion over the next hundred years, and possibly as much as $792 trillion (source). Let’s go over where those costs are coming from. Before we start, go over what you’ve learned and make a list of all the ways you think climate change will impact the economy. As you read, add anything new you learn to your list. Ours is by no means exhaustive.


We’ve all seen the photos of devastation caused by hurricanes and floods and wildfires. These are the obvious economic impacts: people left homeless, businesses forced to close because they can’t afford to repair their buildings, the dollar sums of damage reported on the news. But these aren’t the only impacts. When infrastructure like roads and bridges are destroyed, shipping and transport are disrupted: businesses can’t replenish their stocks and employees can’t travel to work. When one step in a supply chain is taken out, the whole production line grinds to halt. Disasters can also hamper internet connection, locking people and businesses out of the modern information economy.

And it’s not just the extreme weather that’s bad. Studies have found that heat waves and rising temperatures decrease productivity and increase employee absences (source). The loss of productivity is especially prevalent in manual labor and construction jobs, which become more dangerous as temperatures increase. However, absenteeism remains strong regardless of the job. Whether or not this is linked to heat-related health issues is unknown, but the evidence makes clear that the economy will slow as the globe warms, likely by around $2 trillion or more (source).

Rising sea levels

Rising sea levels will flood and displace coastal cities, where millions of people live and billions of dollars of investment are concentrated. As people are forced to migrate, unemployment, homelessness, and other metrics of poverty will increase. Industries located along the coasts will have to either relocate at great expense or shutter entirely, laying off their workers. Damage to infrastructure will also devastate the economy, and not just to coastal areas. Shipping networks and supply chains will be disrupted, as will communications and the power grid.

Plants and animals

It’s difficult to dispute the threats climate change poses to the natural world. Instead, people argue that we should focus on the interests of people over plants and animals. Such a take, however, ignores just how much of the world is dependent on those species.

As referenced in previous sections, the fishing industry is likely to suffer greatly due to warming, acidifying oceans. Shellfish die as they are unable to build their shells. Schools of fish move towards colder water at the poles, away from the people who depend on them for food. Parasites and diseases expand their ranges. Fish migration and breeding seasons are thrown out of sync. Together, these factors spell a collapse of fisheries around the world. The hundreds of millions of people for whom seafood is a staple of their diet will suffer, but we will also see substantial job loss among the people providing those fish. The industry could lose as much as $10 billion a year, with many small scale and equatorial fisheries losing their entire livelihoods (source).

Additionally, the natural world is critical to global tourism. Safaris in Africa, rainforest tours in Costa Rica, and national parks in the United States all rely on their biodiversity and natural beauty to draw visitors. Climate change won’t just bring about extinctions; there are also countless jobs that will be lost when species go extinct and habitats collapse. For example, it’s estimated that Florida’s coral reefs alone generate $1.6 billion of revenue, all of which will vanish if the reefs do (source). Even non-environmental tourism will be affected, as beaches are submerged and ski resorts lose their snow.

Food and water shortages

Between water shortages, rising temperatures, extreme weather, changes in insect distributions, and other factors you’ve read about, agriculture is going to become a lot harder under climate change. Farmers, especially family farms without industrial capacity, will struggle, and many will fail. Over a quarter of the world’s population makes their living from farming (source), and now that livelihood is under serious threat from climate change.

Climate-driven crop failures, when combined with the damage climate change will inflict to fishing and supply chains, will deal a major blow to food security, as discussed above. Even if we manage to avoid widespread famine, food prices will rise (source). Those who can afford their next meal may struggle affording much more than that. In addition, rising food prices can cause economic inflation, leading to even greater poverty (source).

Cause for hope

So are we really caught between a rock and a hard place? We either slow our economy deliberately with carbon prices and environmental regulations, or we let it be ravaged by climate change?

Well, we’ll let you in on a little secret. What you’ve heard about how fighting climate change will hurt the economy and cost millions of jobs is (mostly) not true. We’ll explain more about this in a future section.

Climate change vs. equity

Although climate change affects everyone on Earth, the impoverished and indigenous groups will face significantly worse impacts than the wealthy. Their situation is worsened by the fact that the overwhelming majority of carbon emissions come from wealthy industrialized nations, which they have no control over.

The impoverished

First, let's examine some of these dire situations around the world through this article from the New York Times.

Q: Pick two of the following locations (Greece, Houston, Nigeria, Guatemala, India, and New York City) and compare them: which challenges do they share, and which are unique?

Now, read at least the first two sections of this article from BBC that describes the "climate apartheid" as well as this article from CNBC that covers pre-existing health conditions and "green gentrification."

The impoverished also cannot afford to move out of areas vulnerable to sea level rise and flooding. Who is going to buy a house that will be underwater in ten years? As a result, those in poverty remain trapped as the waters rise.

If you're interested, here are a few additional resources:


Let's read the first three sections of this report from Brookings (through the end of the “Time to envision legal recourse for climate refugees” section), though feel free to read the full article if you'd like. While reading, take notes every time it talks about a number of people being displaced, whether by a specific event (like a hurricane) or by climate change as a whole.

Content warning: the article below includes descriptions of migration that some students might find triggering. If that’s the case, you are exempt from this reading.

Now, let's check out this article from the New York Times (which is also available as audio) and read the introduction, stopping when you reach the interactive model, or at 9:20 in the audio file. Once again, while reading or listening, take notes every time you are given a statistic or number of people being displaced.

The rest of the article is optional, although we strongly recommend the section between “II: How climate moves people” and “One afternoon last summer,” as well as the final section starting from “There is no more natural and fundamental adaptation to a changing climate.”

Q: Look back at all the numbers you have written down. Behind each one is a story just like you encountered in the New York Times article. Take a moment to reflect and to appreciate the extent and scale of what you have read about. You can use the submission box as a space for thoughts, questions, or any method that helps you process what you’ve read.

Indigenous peoples and the global South

Some of the most vulnerable to the effects of climate change are the indigenous populations of the world. We’ll first look at the native peoples of the Pacific Islanders as a case study.

You’ve probably heard about how sea level rise is threatening to submerge entire islands in the Pacific, but this article from Science Alert discusses how the real threat is the contamination of fresh water sources with sea water.

And that isn’t the only issue affecting the islands. As Penehuro Lefale makes clear, “Ocean acidification poses a serious threat to ocean ecosystems, and could have profound impacts on the food security, economy, and culture of communities in the Pacific Islands” (source).

In addition, according to the United Nations, “The impact that climate change is having and will have on the tourism industry [in the Pacific islands] is undeniable. Coral bleaching [due to ocean acidification], mangrove forest inundation, and immersion of turtle nests and sea bird habitats all threaten major assets drawing visitors to [these islands]. Tourists are also discouraged from travelling to [Pacific islands] for fear of yet another violent and life-threatening storm. And as valuable coastland is lost to sea level rise, the resorts and hotels that often occupy that prime real estate will be all the more vulnerable to storm surges and other extreme weather events. If the tourism industry contracts, [Pacific island] economies will suffer devastating losses.” (source)

Lastly, according to the Climate Reality Project, “For Pacific island nations, hurricanes (or as they’re known in the region, tropical cyclones) are already a very real threat. In 2015, Tropical Cyclone Pam hit the Republic of Vanuatu and devastated the nation. It’s considered one of the worst disasters in the country’s history and damages cost the equivalent of 64 percent of the country’s 2016 GDP. This isn’t supposed to happen. As Kiribati’s then-President Anote Tong said in 2015, “When you're on the equator, it's supposed to be in the doldrums. We're not supposed to get the cyclones. We create them, and then we send them either north or south. But they aren't supposed to come back. But for the first time, at the beginning of this year, the Cyclone Pam, which destroyed Vanuatu, and in the process, the very edges of it actually touched our two southernmost islands.” Many small island nations have limited capacity to respond to and recover from natural disasters like this. As hurricanes are projected to become more intense due to climate change, Pacific island nations will be especially vulnerable to their wrath.” (source)

However, as climate change poses such an existential threat to the Pacific islands, they have been some of the best innovators of ways to protect themselves and their environments from it. Some of their methods include climate-smart agriculture (adaptations that boost productivity while decreasing emissions and adapting to climate change, such as using organic fertilizer, raising garden beds to avoid saltwater intrusion, and diversifying crops); protected areas such as green buffers that prevent runoff and water pollution, or marine areas where fishing is seasonally or permanently closed in order to protect coral reefs; and preserving mangrove forests that form a natural barrier against erosion, floods, and storm surges (source). However, all of these efforts are limited by a lack of financial resources, ‘brain drain’ (when talented and educated individuals leave the country), as well as by geographic isolation that makes it difficult, slow, and expensive to get access to necessary materials.

If you want to learn more about threats facing the Pacific islands and their peoples, and the solutions they are addressing to tackle them, you can look at the following optional sources. This website, mentioned above, includes more background as well as breakdowns of issues and adaptations by country. The UN's report on Emerging Issues for Small Island Developing States as well as this World Bank report (page 9 in particular) both detail additional issues affecting the Pacific islands, many of which concern climate change. And this paper describes many methods of adaptation adopted by Pacific peoples.

Of course, the Pacific islands are not the only people threatened by climate change. Read this report about the impacts of climate change on many different peoples from all over the world and how they are adapting.

Activity: Pick an indigenous people or region of indigenous peoples, either from the above report or from anywhere in the world, to research further. Describe at least three specific ways that climate change threatens the survival, health, livelihoods, culture, or other aspects of the lives of the people you have chosen.

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