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Climate Change
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What Is
Climate Change?
With its forests and mountains, oceans and deserts, rivers and fields, and even the plants growing up through cracks in sidewalks, our magnificent planet Earth inspires the people who live on it. Some kids love animals. Some love the ocean. Some love their neighborhood parks. What aspects of nature inspire you?
"I can protect nature by planting flowers and trees."
-Izien, aged 6
Around the world, people are working together to protect nature from a growing threat: Climate change.
Climate change makes people feel many different emotions. Do you feel any of these emotions? Click on a face:
Have you ever wondered why planting trees is so good for the environment? Or why walking or riding a bike, instead of riding in a car, is good for the world around us? These activities are not just fun. They’re also ways to help tackle climate change.
But maybe you’re wondering: What IS climate change exactly?
"I like the natural landscapes in the Catskill Mountains because it is calm and soothing and it's very pretty."
-Alexis, aged 10
1. Let's start by thinking about the difference between weather and climate.
This color-coded map of San Antonio, Texas, on a warm summer night shows how much hotter the city is than the surrounding area. People in redder areas are more likely to suffer health effects like heatstroke.
Look out your window. Is it sunny or cloudy today? Rainy or snowy? Hot or cold? Windy or calm? That’s weather.
What’s it usually like outside where you live? Do you have hot summers and cold winters? Rainy seasons and dry seasons? Mild temperatures year round? That’s climate.
Weather describes the conditions outdoors in a certain place and time, like what's happening today, this week, or this season. Climate is the typical weather in an area over a long period of time (many years).
And climate change refers to the long-term changes in climate shown by global temperatures and other characteristics of the atmosphere.
2. Can we see the effects of climate change today?
Widespread flooding damaged this house near Nashville, Tennessee.
We can see and measure climate changes around the world. Researchers use thermometers to measure the temperature at many spots, then average them together. That average global temperature is rising. Weather patterns are changing, glaciers and ice are melting, and sea level is rising, too. These changes are making it harder for living things to survive in the oceans and on land. They are affecting our ability to grow food and stay safe from extreme weather events.
Climate has changed throughout Earth's long history, but this time it's different. Human activity is causing worldwide temperatures to rise faster than any time we know of in the past.
Wildfire smoke from Canada spread to New York City and other places in North America. For a brief period of time, the air became unhealthy to breathe.
Solar panel arrays provide energy without adding carbon dioxide to the atmosphere.
Can we make a difference by getting involved? Yes.
The choices we make today could reduce the harms climate change can cause. Engineers have already invented technologies to reduce climate change, like solar power and more efficient machines that take less energy to run. We keep improving these technologies and are already making a difference by using them. Now we need to use them on a larger scale.
Kids can ride bikes instead of traveling by car. It’s better for the planet—and it’s fun!
If we work together with our neighbors, we can make a difference in our community. And if communities work together around the world, we can make an even bigger difference. When an entire country switches its power stations from burning coal to using energy from solar panels, that helps a lot! When a city passes a law requiring new buildings to use windows that keep heat inside during the winter and outside during the summer, that helps too. When you ride your bike or take a bus instead of traveling by car, that helps a little—and every little bit counts.
3. How does Earth’s atmosphere protect us?
Throughout our planet's history, global temperatures have risen and fallen naturally. At times, some species could not adapt to these changes and went extinct. But once life really got going on Earth, there’s always been something alive here. That's because Earth is wrapped in its own protective blanket of air, a mixture of gases called the atmosphere.
Energy radiates from the Sun. When the Sun’s energy reaches Earth’s atmosphere, some reflects back out into space, some is absorbed by the atmosphere, and some travels down to the surface.
Some of the energy that reaches Earth's surface is reflected back out into space. The Earth absorbs the rest. The absorbed energy then radiates out from the surface as heat energy.
Certain gases in the atmosphere absorb this heat energy. This causes the atmosphere near Earth’s surface to warm, reaching temperatures that allow plants and animals (including humans) to live. This process is called the greenhouse effect, and the heat-absorbing gases in the atmosphere are called greenhouse gases, because the atmosphere holds in heat like the clear walls of a greenhouse.
The main greenhouse gases are carbon dioxide, water vapor, and methane. The more of these gases there are in the atmosphere, the warmer Earth gets. But when it gets too warm, too fast, it's harder for many plants and animals to survive.
4. What is carbon dioxide, and what is causing it to increase in Earth’s atmosphere?
A model of a carbon dioxide molecule
Carbon dioxide is an invisible gas in the air that forms when two oxygen atoms bind to a single atom of carbon. Carbon is the fourth most abundant element in the universe. It’s everywhere on Earth: in rocks, the ocean, the atmosphere, and all living things.
Burning fossil fuels is the main way that humans are increasing the amount of carbon dioxide in the atmosphere. We burn fossil fuels for manufacturing, agriculture, transportation, powering our homes, and—more and more—the computers that process our data. We also increase carbon dioxide levels in other ways. Cutting down or burning trees increases atmospheric carbon dioxide, for example. And when manufacturers heat up limestone to make cement, they release carbon dioxide into the atmosphere.
Today, there's more carbon dioxide in the air than anytime in at least 800,000 years. That's 8,000 centuries!
One way we can reduce the amount of carbon dioxide in the atmosphere is by planting trees. Through photosynthesis, trees and other plants use the energy in sunlight to convert carbon dioxide gas into the carbon-based chemicals they need to grow. That removes carbon dioxide from the atmosphere and turns it into plants!
5. How do we know that climate is changing?
Scientists drill deep into the ice to bring up samples like this one in Antarctica. The ice holds valuable information about what the climate was like in the past, when each layer formed.
To study climate, scientists analyze measurements from weather stations around the world and satellites overhead. They record things like temperature, air pressure, humidity, and even the chemistry of the atmosphere. And they use information from satellites, ships, and buoys spread across the oceans to measure the temperature and chemistry of the ocean.
To understand how climate is changing, scientists also look back into Earth's past— hundreds, thousands, and even millions of years. For this information, they find clues from Earth itself, in tree rings, corals, deep-sea sediments, ice sheets in Antarctica and Greenland, and glaciers on tops of mountains.
6. How has weather become more extreme?
Climate change is affecting weather around the world. For example, higher temperatures are changing how much rain falls, where, and when. These changes are having a big impact on our planet and all its living things, including us.
Intense rainstorms and flooding have become more common. As ocean temperatures rise, so does evaporation. Extra water vapor in the air leads to heavier rain and snow and more-powerful hurricanes and tornadoes. See how flooding affected the area around the capital of Chad from September of one year to October of the following year.
Droughts are becoming more intense and are happening more often. Monsoons have become less predictable. Hotter soils get drier faster. In many dry areas, there is less water in the soil to evaporate into the air, so there is less rainfall. See how Lake Albert, Oregon’s only salt lake, shrank over 20 years.
Erosion is increasing along coastlines and riverbanks as sea levels rise, rivers flood, and powerful storms send heavy waves crashing into land. See what happened to this coastline in Great Britain after 20 years of erosion.
7. How does melting ice affect the world?
As temperatures warm, ice is melting at Earth's poles in Antarctica and Greenland. The impact is global.
Rising sea levels can cause flooding on sunny days, like here in San Francisco.
Sea levels on the rise: All this fresh water entering the ocean is raising sea levels. Flooding is increasing along many coastal areas, and over the next century, more of these areas will be underwater. That’s dangerous for the people living there. And it’s dangerous for the plants and animals living there too, like crabs and clams, sea grasses and seals, mangroves and manatees.
Shrinking habitat crowds walruses together in smaller areas, where they trample and injure one another.
Habitats harmed: Animals like polar bears, walruses, and penguins are losing the habitats where they hunt, nest, and breed. Closer to the equator, mangrove forests grow along coastlines with their roots in the water. Rising sea levels could disrupt their root systems. Many birds and fishes, including baby sharks, rely on mangrove swamps. And people living nearby are affected too.
Even warmer temperatures: If you have ever walked outside barefoot, you might have noticed that dark pavement streets get hotter than light cement sidewalks. That’s because dark surfaces absorb heat from the Sun and light surfaces reflect it. Snow and ice are like a light sidewalk because they reflect more of the Sun's energy back into space than dark areas. As ice-covered areas shrink, less energy is reflected. In the ocean, open water absorbs more energy, which heats it up. As temperatures rise, more sea ice melts and the ocean absorbs even more heat!
Grinnell Glacier is melting in Glacier National Park.
8. How do changes in the ocean affect climate, and vice versa?
Acidifying seawater means fewer shell-forming organisms like sea urchins for predators like sea otters to eat.
The ocean absorbs huge amounts of heat and carbon dioxide from the atmosphere, but with carbon dioxide increasing so much and so quickly, the ocean is changing.
These changes make survival difficult for many marine animals. Over the past 200 years, ocean waters absorbed about 30 percent of the carbon dioxide released by humans. This has changed the chemistry of the water, making it less basic. In chemistry, the word basic has a special meaning. It’s the opposite of acidic. In other words, the ocean is acidifying. This makes it harder for shell-forming organisms to grow their shells. Eventually, they could disappear. And since these shells convert carbon dioxide into other carbon compounds, fewer shells mean more carbon dioxide in the atmosphere and even more warming. And it affects food webs, too. Animals that eat shellfish go hungry.
Warming waters kills coral, leaving behind whitened reefs and making it hard for other animals to live there. See what happened on this reef in the Pacific Ocean over three months.
Tiny plantlike organisms called phytoplankton live in sunlit ocean water.
Warming ocean water also threatens populations of phytoplankton. Phytoplankton are tiny, plantlike organisms floating in the sunlit parts of the ocean, where they use the Sun’s energy to perform photosynthesis. In the process, they convert carbon dioxide into breathable oxygen. Because there are so many phytoplankton, they do an enormous part of the work of removing carbon dioxide from the atmosphere and producing the oxygen that we need to breathe. And since so many animals eat phytoplankton, those animals are threatened too. That in turn affects the animals that eat those animals, and so on, including us!
And finally, changes in the ocean may alter ocean currents. These currents bring warm water to cold areas and cool water to warm areas, warming and cooling the air and land as well. If the currents change, it could affect weather patterns around the world.
9. How can we make a difference?
Composting turns food waste into fertilizer for soil, helping plants grow.
Young people around the world are concerned about the health of our home, Earth. They are envisioning a future that protects the places they love, like a nearby beach, river, forest, or city park, along with the plants, animals, and people that live there. Fortunately, there’s a lot we can do to be part of that future and to protect our favorite places.
Here are some of the things we can do ourselves:
- Talk about what nature means to us and how we feel about climate change. The more people talk about nature and climate change, the better the chance that people will take action.
- Plant trees or pollinator gardens and take good care of them. Plants absorb carbon dioxide from the air. Pollinators help plants reproduce and help other species thrive.
- Walk, take the bus, ride a bike, or carpool.
- Turn off lights and other electronics when not using them.
- Recycle and reuse products, since making new stuff requires more energy.
- Paint building rooftops white, to reflect sunlight and keep buildings cooler.
One of the most important things we can do is work together to lower the amount of greenhouse gases we put into the atmosphere. We can encourage our communities and governments to switch to clean energy sources like solar, wind, and geothermal power.
There's no single answer to stopping climate change. It's going to take many different solutions. When we all speak up to our friends, families, teachers, and community leaders and work together, we can make a real difference.
Credits:
Urban heat map, City of San Antonio Office of Sustainability; flooded house, Jett Loe/Flickr; wildfire smoke over NYC, EarthCam; solar panel array, Office of the President of Mexico/Flickr; kids on bikes, Bike SLO County/Flickr; extracting ice core, © Robert Mulvaney/British Antarctic Survey; Chad river flooding, NASA; Lake Albert, NASA; Great Britain erosion, Mike Page Aerial Photography; sea level rise San Francisco, Michael Filippoff/NOAA; walrus, USFWS; Grinnell glacier 2016, USGS; Grinnell glacier 2023, NPS; sea otter, NOAA; coral bleaching, © XL Catlin Seaview Survey – The Ocean Agency – Richard Vevers; phytoplankton, NOAA; kids composting, Seattle Parks and Recreation/Flickr