So: The study finds a fingerprint of anthropogenic influences on large scale increase in precipitation extremes, with remaining uncertainties — namely that there is still a possibility that the
widespread increase in heavy precipitation could be due to an unusual
event of natural variability.The intensification of extreme
rainfall is expected with warming, and there is a clear physical mechanism for it, but it is never possible to completely separate a signal of external forcing from climate variability — the separation will always be statistical in nature.