Every major scientific institution that studies the climate — including the IPCC, NASA, NOAA, and the National Academies of Sciences, Engineering, and Medicine — has independently reached the same conclusion: human activity is the dominant cause of observed global warming since the mid-20th century. This is not a matter of ongoing scientific debate; as NOAA Climate.gov states directly, "there is no debate about the cause of this warming trend."
The strength of this consensus rests on quantitative attribution science, not just agreement. IPCC Sixth Assessment Report (AR6) studies, published in peer-reviewed literature and summarized by PMC, calculate that human greenhouse gas emissions caused approximately 1.07°C of warming between the 1850–1900 baseline and 2010–2019. By contrast, natural factors — including solar variability and volcanic activity — contributed only between –0.1°C and +0.1°C over the same period. Mathematically, natural causes cannot account for the observed warming trend.
Dissenting claims circulate in blog posts and opinion media, but none have produced peer-reviewed quantitative attribution evidence that challenges the IPCC methodology. NASA Science explicitly attributes the warming trend observed since the mid-20th century to the human expansion of the greenhouse effect. The National Academies describe the evidence for human-caused harm as "beyond any reasonable doubt," reflecting the same conclusion reached through entirely independent lines of research.