I think saying it's proof is a bit strong, at least in the context of something like a math proof. Taken collectively extreme changes in weather provide evidence that we're seeing climate change, but we need more years of data before we can say anything conclusive. Ironically enough, if we wait and collect a lot of data while trundling along with business as usual we could make things a lot more expensive to deal with for later generations. Generally speaking it's at least worthwhile to go with cost neutral GHG abatement. If we're wrong and GCC isn't an issue, we wouldn't be spending any more than we normally would have, and if we're right we probably saved ourselves a bundle in GCC costs down the road. Of course doing to would really cut the profit margins for fossil fuel energy producers, so we're probably seeing a two prong advertising approach by PR firms on their behalf. One is
to convince people that those FF companies are looking for alternatives to solve the problem, and another to try to convince people that there really isn't a problem. Cutting FF demand in half would crater the bottom line of those companies because their net production would fall and prices would fall. They could see net revenue drop to a third or less of what it was when demand for FFs was stronger.