Consensus has not been reached on how the claimed effect called Global Warming should be measured.
'Scientific consensus' is one of the popular measures people use to determine whether the effect exists. In the 'scientific consensus' determination, all scientists relevant to the issue would agree that the effect exists. Questions of who we should consider relevant, and how the named effect should be defined, often remain as sub-camps of the group promoting 'scientific consensus' as meaningful to the issue.
'Scientific method' is another of the popular measures people use to determine whether the effect called Global Warming exists. Using the 'scientific method' requires hypotheses predicting precisely measurable effects of the Global Warming model that would not happen otherwise, such as a certain unusual global temperature being reached by a certain date, or a duplicatable laboratory demonstration of carbon effect on temperature. By definition, the 'scientific method' always leads to a test that can be independently verified, and the test always has both a pass and a fail state. Questions of what measure we should use to determine global temperature, and what tests we should create to determine whether man plays a significant role in changing any measured temperature reading, often remain as sub-camps of the group promoting 'scientific method' as meaningful to the issue.