This is a good opportunity to point out this strategy of climate denial, and why it is not a rational approach to refuting climate change. Let's suppose that a

This is a good opportunity to point out this strategy of climate denial, and why it is not a rational approach to refuting climate change. Let's suppose that all the other commenters are wrong, that the river has not changed course in the past. The implication, from a probabilistic perspective is that P(evidence|climate change) is the same as P(evidence| natural variation), and your implied assumption is that because your prior belief that no climate change is more likely than climate change, then this works ultimately as evidence in favor that there is no climate change. The reason this does not yield interesting results, even if all these other assumptions we're making hold, is because the hypothesis of climate change doesn't simply explain this one observation, it explain an enormous range of phenomena. To explain away all of the observations explained by climate change you end up building a huge list of different hypotheses to explain away each fact. Even if individually these alternate hypothesis do explain each piece of evidence better (which in practice they often don't), and even if your prior for all of these other hypotheses is higher than climate change, because climate change is a single hypothesis that explains many observations, the joint probability of the individual hypothesis quickly becomes much lower than the climate change hypothesis. In order to effectively argue against climate change you would need a competing singular hypothesis (or small set of very likely hypotheses) that ultimate do a better job explaining all of the observations we have collected. I don't know if this fallacy has a name, but it sure should since it comes up in a lot of arguments about systemic problems.