Human activity is causing global warming
How do we know we're behind climate change?
Scientists have closed the case: Human activity is causing the Earth to get hotter.
How: Primarily by burning fossil fuels, with a smaller contribution from deforestation.
Scientists have considered and ruled out many other explanations for why our planet is warming.
How our activity leads to climate change
When we extract and burn fossil fuels such as coal or petroleum, we cause the release of carbon dioxide (CO2) and other heat-trapping "greenhouse gases" into the atmosphere.
Though natural amounts of CO2 have varied from 180 to 300 parts per million (ppm), today's CO2 levels are around 400 ppm. That's 30% more than the highest natural levels over the past 800,000 years.
We also can tell that the additional CO2 in the atmosphere comes mainly from coal and oil because the chemical composition of the CO2 contains a unique fingerprint.
Losing forests makes it worse
Clearing forests also releases large amounts of CO2. On top of that, plants and trees use CO2 to grow. Worldwide deforestation means we don't have as many trees to absorb the extra CO2.
This means more CO2 stays in the atmosphere, trapping more heat.
So what do we do about it?
The climate is changing, but so are the political and business climates. There's a path forward, and thousands of people like you are helping.