What sparked global warming? People did.

By burning fossil fuels and destroying forests, humans trap Earth's heat

Man looking at emissions from industrial smokestacks
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When we drive, fly or power our homes with air-polluting sources, we release gases that heat our planet. The science is clear.

Burning fossil fuels does damage

Burning fossil fuels such as coal or petroleum sends carbon dioxide, methane and other heat-trapping “greenhouse gases” into the atmosphere. Gradually, temperatures climb.

Think of it like a thermal blanket around the Earth.

Clearing forests worsens warming

Chopping down vast swaths of forests, known as clear cutting or deforestation, adds to the problem. Such drastic removal of trees is being driven by the agriculture, timber and other industries.

We need the trees because they absorb carbon dioxide. Fewer trees means more of the gas hangs in the atmosphere, trapping more heat.

The chief danger: carbon dioxide

Carbon dioxide has caused most of the warming, science tells us. We can measure it.

For 800,000 years, natural amounts of carbon dioxide ranged from 180 to 300 parts per million (ppm). Today’s levels are around 400 ppm – up 40 percent since the Industrial Revolution began in the mid-18th century, when the level was 280 ppm.

We know this extra carbon dioxide comes mainly from burning coal and oil because of the chemical composition of the gas.

Here’s what you can do

Sure, there are simple, everyday steps – such as driving the speed limit, recycling and unplugging electronics you’re not using.

But you can also do your part to propel large-scale progress: Tell your leaders where you stand and voice your support for climate legislation.

Just sign up below to receive news and alerts. We’ll send you quick opportunities to reach out to your elected officials and others who can help spur big change.

Scientists are more confident than ever that humans are causing global warming.

Ilissa Ocko Ilissa Ocko Climate Scientist
  • 97%percentage of scientists who say humans are to blame for global warming
  • 40%rise of carbon dioxide in the atmosphere since the Industrial Revolution
  • 70 millionmetric tons of carbon dioxide we add to the atmosphere daily

Sources: “Consensus on consensus,” U.S. National Climate Assessment and NOAA

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Sources
Scientific information drawn mostly from EPA's Climate Change coverage.