I wanted to discuss a recent paper by a fellow member of the UC faculty, J.D. Neelin down at UCLA, and several of his collaborators. This paper lays out in a very simple way the manner in which total storm rainfall will likely change under global warming conditions. What I think is particularly useful about what the authors do in their work is that they note not only that storm intensity will likely increase under global warming but also that storm duration might change. Total rainfall from a storm (or at a particular location on Earth) is the result of the storm intensity and the storm duration. A colleague of mine back at Colorado State was fond of saying that “the most rain occurs where it rains the heaviest for the longest” which is a very simple statement but one that has often been forgotten in the global warming discussion. There are many practical reasons for this neglect, not the least of which is that we often lack temporal resolution of storms in climate models, our chief tool for predicting a future world. Neelin et al point out that the largest storm-total-accumulation values will likely rise due to global warming. And, I would suggest that their argument for why this is true relies uniquely on physical reasoning. We observe that many properties of clouds, including, apparently, total storm accumulation, obey simple power-law scalings. Global warming will likely affect the properties of these power-laws which will likely result in higher frequencies of what would in the current climate be considered extreme rainfall accumulations. Anyway, check out the paper — it’s freely available at PNAS.