What does the number 400 mean to you? If you’re a math whiz, you know it’s 20 squared. If you’re a chocoholic, you might recognize it as the amount of calories in a small stack of chocolate chip pancakes. If you’re a car-racing fan, it’s the amount of laps in a NASCAR race.
But for those who study climate change, 400 is the amount of parts per million (ppm) of carbon dioxide that is now in the Earth’s atmosphere. Never before has this much carbon dioxide accumulated in the atmosphere in such a short time. The last time there were 400 ppm of carbon dioxide was 3 million years ago. Back then, the average temperature of the Earth was warmer and the sea level was between 60-80 feet higher than it is today. But back then, it took tens of thousands of years to reach 400 ppm. Now, we’ve reached that number in just over 150 years. And today we’ve got 7 billion people living on the planet.
What does 400 mean for the Earth? What does this mean for you?
400 ppm means the average temperature of the Earth is guaranteed to get 3.5 degrees hotter. This means more heat waves, longer lasting droughts, stronger hurricanes, and heavier flooding.
But 400 also means that if we drastically limit the burning of fossil fuels all over the world, we can stop this number from going up to even more dangerous levels.
Here’s what you can do:
- Create a Kids-Stop-at-400 club at your school. Gather signatures to send to your congressional representative.
- Carpool, ride the subway or bus, or walk as much as possible. If your family is in the market for a new car, talk to your parents about making it a hybrid or an electric one.
- Ask your school about signing up for a solar lease program. In some cities, it doesn’t cost a dime to put solar panels on the roof.
- Use recycled paper products to keep more trees alive and absorbing carbon dioxide.
- Write to President Obama and tell him that you want to reduce the burning of fossil fuels such as oil and coal, and stop exporting coal to other countries.
Imagine a future in the next 50 to 100 years when we completely move away from burning fossil fuels to get energy. You have the ability to help make that future a reality. 400 is definitely big and bad. But the power of our voices and our actions can be even bigger and badder. Join the Save Planet Message Board to talk to other kids about the Big, Bad 400.
— Laurie David and Cambria Gordon, authors of The Down-to-Earth Guide to Global Warming