One of the points of debate about climate change has been leveraging the claim that climate change is causing more extreme weather against the fact that weather has always been prone to extremes. Weather is naturally variable and there have always been droughts, heat waves, severe storms and floods. Climate change does not cause these things, but it can make them more intense or cause them to happen more frequently. A recent article in Phys.org has cast illumination on the method of attribution science.
The idea is that by analyzing the intensity and frequency of certain weather events over time, and factoring in changes in population and land use, it can be fairly precisely estimated what additional impact has come from climate change. Global climate models are only capable of predicting future climate in very general terms but this type of extreme weather analysis allows us to estimate the probabilities of certain types of events in the future, given the general forecasts from the climate models.