claim: The IPCC ( 2013 ), USGCRP ( 2017 ), and USGCRP ( 2018 ) indicate that it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-twentieth century.
evidence: The Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded, It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.