The Earth's climate is changing. In most places, average temperatures are rising. Scientists have observed a warming trend beginning around the late 1800s. The most rapid warming has occurred in recent decades. Most of this recent warming is very likely the result of human activities.
Many human activities release "greenhouse gases" into the atmosphere. The levels of these gases are increasing at a faster rate than at any time in hundreds of thousands of years.
We know that greenhouse gases trap heat. If human activities continue to release greenhouse gases at or above the current rate, we will continue to increase average temperatures around the globe. Increases in global temperatures will most likely change our planet's climate in ways that will have significant long-term effects on people and the environment.
To read more, visit the EPA's website on Climate Change.