What’s Happening?

No one is sure what is causing the worldwide warm-up. Most scientists blame some gases in Earth’s atmosphere. They point to one gas in particular—carbon dioxide.

Most people depend on oil, coal, and natural gas. These fuels help run cars, heat homes, and power factories. But they also give off carbon dioxide. Carbon dioxide heats the atmosphere and makes Earth warmer.

Over time, cars and factories have changed the atmosphere. Today, the air has about 30 percent more carbon dioxide than in the days before cars and factories. Other heat-trapping gases have also skyrocketed.

Each year, people cut down a lot of trees for paper and wood, and this is a problem because forests actually help lower carbon dioxide levels. Trees use carbon dioxide to make their own food.

When people cut down forests, more carbon dioxide hangs around in the atmosphere. That drives temperatures even higher.

People also produce a lot of trash, and most of it gets dumped into landfills. These are areas filled with trash and then covered with dirt.

As trash sits in landfills, it makes methane gas. The methane rises into the air and traps heat. More trash means more methane, and more methane means a warmer Earth.

The message, scientists say, is clear. People need to change their ways—beginning now, not next year. The future of Earth is at stake.

Methane gas from landfills can make Earth warmer.