Earth and Human Activity

Climate Change

You probably hear a lot about climate change these days. What is it, and what does it mean for Earth’s future… and for you?

Earth’s climate has experienced plenty of ups and downs before. There have been Ice Ages, when much of the planet was covered in ice. There have been warm periods, too. These changes in climate occurred because of natural processes. They took place gradually, over hundreds or thousands of years.

But the current change in Earth’s climate is different. It is happening more quickly than other times. And we know that it is caused by human activity.

How do we know that? By studying data such as gases trapped in old layers of ice, scientists have determined that levels of carbon dioxide began to rise quickly around the mid-1800s. Carbon dioxide in the atmosphere is directly connected to temperature because it is a greenhouse gas that traps heat. Sure enough, the mid -1800s is just when humans first began burning a lot of fossil fuels.

Since then, the level of carbon dioxide in the air just keeps rising faster and faster…much faster than ever before. And it’s clear that average temperatures are rising along with the increased carbon dioxide.

What causes climate change?

So, there is very little doubt that climate change is caused by human activities which generate greenhouse gas emissions. Greenhouse gases trap infrared radiation from the sun inside the Earth’s atmosphere. That heats up our planet. The main greenhouse gases are carbon dioxide (CO2) and methane.

Carbon Dioxide

When you exhale, you breathe out carbon dioxide, but that isn’t what causes global warming. The carbon dioxide produced by cars, trucks, and industrial processes is the biggest contributor to climate change, because it changes the natural balance of our atmosphere. Plants naturally absorb carbon dioxide, so when we cut down forests, we also cause more carbon dioxide to end up in the atmosphere.

Once carbon dioxide is in the atmosphere, it stays there for up to 1,000 years. That is why it’s important to reduce our emissions now, before the change to the climate becomes irreversible.


Methane is released during oil, gas, and coal production. Farm animals also produce methane. In case you were wondering: yes, cow farts do contribute to global warming. Another source of methane is rotting garbage.

Methane emissions are much smaller than carbon dioxide emissions. And methane only lasts for about nine years in the atmosphere. However, methane traps 28 times as much heat as carbon dioxide, so it can have a big effect on climate change.

The climate changes differently in different parts of the world

Climate changes differently in different places

Just since the 1950s, Earth’s average temperature has increased by almost two degrees Fahrenheit. That may not seem like a lot. Most of the time you probably won’t even notice the difference.

Yet, on a larger scale, those few degrees are already making a lot of difference. That’s because Earth’s climate, weather, oceans, and ice are all connected in complex ways. As temperatures shift, so do precipitation patterns, ocean currents and temperatures, and yes, even the weather in your town.

In some regions, warmer ocean temperatures are already causing stronger and more frequent hurricanes. In other places, the changes aren’t quite so stormy, but still have a big impact. For example, as climate warms, some areas are getting more rain and less of the mountain snow that stores moisture for summer. This shift in precipitation pattern is already causing floods in winter and droughts in summer. That makes it harder to grow the crops we rely on for food. And it might change where humans are able to live, because we all need water every day.

There are many other impacts, too. For example, as carbon dioxide increases in the atmosphere, more is absorbed by the oceans. That is causing the oceans to become more acidic. The increased acidity, in turn, damages coral and the shells of many sea animals.

What causes climate change?

Melting Ice, Rising seas

Climate change is having its biggest effect on the coldest places on earth. The Arctic is warming twice as fast as the world average.

One reason for this is that bright ice reflects the sun’s heat, while the darker surfaces of water and land absorb it. As temperatures warm and Arctic ice melts, more water and land are exposed. These absorb more heat, making temperatures even warmer. That causes more ice to melt. Scientists call this a feedback loop. It is already affecting many people and animals that live in Earth’s Arctic regions.

In Antarctica, warmer ocean water and temperatures have caused ice sheets to collapse. As ice in the polar regions melts, sea levels are rising. Ocean water also slightly expands as it warms, and that is also contributing to higher sea levels.

Sea level has already risen by about 20 centimeters (8 inches) since 1900, which has already caused more flooding along the coasts. If all the ice and glaciers on Earth were to melt, sea level would rise 70 meters (230 feet). That would flood every coastal city on the planet. Even if you don’t live near the North or South Pole, this could affect you.

What can we do?

If you only remember one thing about climate change, remember that it changes lots more than just temperature. Shifts in climate impact everything from oceans to land to ice to animals to…us.

That is why people all around the planet are looking for ways to help slow climate change. The key, of course, is to reduce greenhouse gases so that Earth’s atmosphere doesn’t trap so much heat.

Some solutions are big, like building cars and factories that don’t use as much fossil fuels. But there are plenty of are smaller things we can all do. We can recycle more. That way, we won’t produce so much garbage, and factories won’t have to burn fuel to make so much new stuff. We can also try to use cars less, and buses, feet, and bikes more. If everyone pitches in, we still have time to give our planet, and ourselves, a healthier future.

Written by Laura McCamy

Edited by Beth Geiger, MS Geology

Illustrated by Renee Barthelemy