Earth's climate is changing in ways that affect our weather, oceans, snow, ice, ecosystems, and society.
Natural causes alone cannot explain all of these changes. Human activities are contributing to climate change, primarily by releasing billions of tons of carbon dioxide (CO2) and other heat-trapping gases, known as greenhouse gases, into the atmosphere every year. 
Climate changes will continue into the future. The more greehouse gases we emit, the larger future climate changes will be.