A Recent paper by Jarl Kampen, entitled “A methodological note on the making of causal statements in the debate on anthropogenic global warming" (AGW) is right on that we can’t test anthropogentic climate change, because we can’t do an experiment with replicate control and treatment earths (at least 3 treatment and 3 control earths to do it well). Since we only have one earth (a treatment), then the best way to verify anthropogenic climate change is to develop potential falsifiers and evaluate those. As they state, “failure to find falsifying evidence in empirical climate data will render the AWG hypothesis much stronger.”
I fully agree with this concept, however, I would argue that we have spent 40 years doing just that. The scientific consensus that global warming is real and that it is derived by anthropogenic means didn’t happen overnight. Scientists are careful, skeptical, evidence-driven people. There have been multitudes of efforts by scientists to come up with alternative explanations. If a scientist could effectively disprove AWG, they would be very famous, so there has been ample incentive for scientists to develop alternative explanations to falsify AWG. Many have developed good faith alternative explanations and evaluated them. But all attempts thus far have failed, gradually resulting in the scientific consensus we now have. Good scientists should and will continue to try to develop falsifying evidence, but given the hundreds and hundreds of papers accumulating in support of global warming science, it is difficult for most scientists to imagine an alternative theory.
Kampen’s paper is fine, and I don’t disagree with it. But it would have been stronger if the reviewers had required the paper to do a review of attempts to develop alternative explanations (as they suggest should be done). Without that, the paper makes it appear as if it hasn’t occurred to scientists to attempt to develop and evaluate alternatives to AWG, and nothing could be further from the truth.