There is a wealth of evidence that Earths climate is changing, and that humans are the main cause of this change. Here are some of the key pieces of evidence from the search results:

• Temperature records: Daily high and low temperatures have been recorded at thousands of weather stations worldwide, and these records show that the world is warming.

• Paleoclimate evidence: Ancient evidence from sources such as ice cores, tree rings, and sedimentary rocks reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age.

• Observations of the natural world: Birds are migrating earlier, marine species are moving north, plants are blooming earlier, and mountain glaciers are melting worldwide. These changes are consistent with a warming planet.

• Greenhouse gases: Scientists have demonstrated the heat-trapping nature of carbon dioxide and other gases, and there is no question that increased greenhouse gas levels warm Earth in response. Carbon dioxide from human activity is increasing more than 250 times faster than it did from natural sources after the last ice age.

• Fingerprinting: Scientists use fingerprinting to study the causes of climate change. Different influences on climate lead to different patterns seen in climate records. Observed atmospheric temperature changes show a fingerprint much closer to that of a long-term CO2 increase than to that of a fluctuating Sun alone.

• Scientific consensus: Multiple scientific associations have issued statements affirming that climate change is occurring and that humans are the primary cause. Currently, more than 97 percent of publishing climate scientists agree on the existence and cause of climate change.

Taken together, these lines of evidence point squarely to human activities as the cause of recent global warming.