A new U.S. government report shows that climate is changing and that human activities will lead to many more changes. These changes will affect sea levels, drought frequency, severe precipitation, and more. The Climate Science Special Report (CSSR), created by a U.S. government organization that coordinates and integrates federal research on changes in the global environment and their implications for society, also lays out the current state of science relating to climate change and its physical effects. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century, the report concludes. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.