More and more studies are seeking to assess more specifically the anthropogenic footprint on singular meteorological events after they have occurred. The question is not about whether if the event was caused by climate change, because in most cases the event could very well have occurred without human modification of the climate, solely because of the natural variability of the climate. The point is to estimate whether the probability of the event occurring has been modified by climate change, and if so, by how much. This is referred to as a risk ratio (RR) or risk fraction attributable (FAR = 1 – 1/RR) to climate change (and therefore, indirectly, to human activities).