The amount of carbon dioxide in the atmosphere has a strong correlation with rising temperatures.
Since the first Earth Day in 1970, the average annual temperature in every state has climbed.
More water is flowing this year in California from frequent storms and melting snowpack.
Western snowpack at the end of the the wet season is up this year — but that's less likely in the future.
As the climate changes, see the trend in warmer-than-normal spring days in these cities.
See how many days this winter were warmer or colder than average in your city.
As the climate warms, maples are being tapped earlier in the year to get the sap that produces syrup.
The 10 hottest years ever recorded have all occurred since 1998.