How much CO2 is in the atmosphere?

In 2021, the concentration of

carbon dioxide (CO2) in the Earth's atmosphere was 414 parts per million (ppm). This number varies considerably by measurement location and time of year. CO2 levels also keep increasing due to human activities like burning fossil fuels and deforestation.

Let’s dive a bit deeper…

Climate change is caused in part by greenhouse gases, like carbon dioxide (CO2). They're called greenhouse gases because they produce a greenhouse effect by trapping more heat in Earth's atmosphere.

To be sure, it's a good thing that there are greenhouse gases like CO2 in our atmosphere. Without them, the Earth would be too cold for us to live. Still, if there are too many greenhouse gases in the atmosphere, it might get too hot for us.

As a result, you hear a lot about CO2 emissions from things like power plants, cars, and planes. You hear politicians and policymakers talk about needing to reduce emissions, and you read articles online arguing about the best ways to do that.

All of this can get confusing. Let's get the download on getting CO2 back down low.

Show me the numbers

The main greenhouse gas you hear about is CO2. There are other ones, like methane (CH4) and nitrous oxide (N2O). All are important and exist in different concentrations in the atmosphere. For today, we’ll focus mostly on CO2.

One tricky thing about these gases is that you can't see them like you can see plastic pollution on the beach. But just because we can't see them doesn't mean we haven't been dumping them into the environment. Maybe if we could see them, we'd have changed our ways long ago.

To understand how much CO2 is in the atmosphere, it helps to break down the concept of parts per million. To use a metaphor, if the Earth's atmosphere were a beach with 1 million grains of sand, only 420 of those grains would be CO2 particles.

That corresponds to one measurement of how much CO2 is in the atmosphere from 2022. Researchers at the Mauna Loa observatory in Hawaii measured CO2 concentrations as 420 parts per million. Based on that, it’s also accurate to say our atmosphere is 0.042% CO2.

That's like… not that much, right?

Parts per million may seem like a small quantity. But humans have significantly altered our atmosphere's composition in a short amount of time. Before the Industrial Revolution, there were never more than 300 parts per million of CO2 in the Earth's atmosphere. As we noted, today there are ~420 parts per million. That's a 40% increase in ~300 years!

And that can make an impact. Generally, the higher the level of CO2 ppm in the atmosphere, the warmer the Earth gets. As NASA once explained, there are ~400 ppm of caffeine in a cup of coffee. If you feel a kick from your morning joe, you know 400 ppm can be powerful!

And the Earth is experiencing the power of parts per million. Average temperatures globally have increased by more than 1° C over the past 100 years.

How did we get here?

Next question. Why is there more CO2 in the atmosphere now than before?

In the 20th century, we started burning fossil fuels to make electricity, move cars and ships, and power industrial processes. Burning fossil fuels releases greenhouse gases into the atmosphere. The more we burn, the more greenhouse gas levels in the atmosphere increase.

You’ve probably heard of the Industrial Revolution. That’s when CO2 levels in the atmosphere really started increasing. Enterprising people in the U.K., the U.S., and elsewhere realized that burning coal was more productive than burning wood, whether to heat a home or make steel.

Since then, we haven’t slowed our roll. We burn more coal, oil, and natural gas than ever. Even though other technologies like solar and wind are making progress for power generation, oil and coal are still the largest fuel sources for energy globally.

What should we do?

Experimenting with our atmosphere on the scales we have been for hundreds of years is irresponsible, not just for us, but for all species and life on Earth.

The first step to unwinding some of this dangerous experiment is transitioning society off fossil fuels for energy. Which won’t be easy – fossil fuels still provide 80% of global energy.

But in order to reverse climate change, we also need to remove excess CO2 from the atmosphere. That won’t be easy, either.

Still, many natural systems already remove CO2 from the atmosphere. Plants and trees are a good example; they’re constantly soaking up billions of tonnes of CO2 from the air to turn it into sugar and oxygen via photosynthesis.

Humans are also getting better at engineering new carbon removal solutions. Examples include giant fan-like machines that suck CO2 out of the air. Or reactors that turn plants into oil so we can inject it back underground.

Whether via engineered solutions, natural systems, or both, scaling the world’s carbon removal capacity is vital to reversing climate change.

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