One final note: Other readers raised questions about the role of technological change — such as evolving building practices — and its effects on disaster losses over time. This subject is well addressed in the literature, and has been deemed important in damage trends with respect to Australian cyclone damage and U.S. earthquakes, for instance, but not for floods, U.S. hurricanes or tornadoes.He's got a link for "floods," a lengthy article that cites repeatedly to RPJr but not one that does much to support his assertion. Instead it has a significant section on how flood protection efforts over time have reduced damages (or sometimes make things worse when done wrong) and concludes:
Based on the evidence recently assessed in the SREX report (S12), one can assess at present that it is likely that there have been statistically significant increases in the number of heavy precipitation events (e.g. 95th percentile of 24-h precipitation totals of all days with precipitation) in more regions than there have been statistically significant decreases, but there are strong regional and sub-regional variations in the trends, both between and within regions. Based on cumulative evidence, there is additionally medium confidence that anthropogenic influence has contributed to the intensification of heavy precipitation at the global scale, though attribution at the regional scale is not feasible at present. Projected changes from both global and regional studies indicate that it is likely that the frequency of heavy precipitation, or the proportion of total rainfall from heavy falls, will increase in the 21st century over many areas of the globe, especially in the high-latitude and tropical regions and northern mid-latitudes in winter. Heavy precipitation is projected to increase in some (but not all) regions with projected decreases of total precipitation (medium confidence).
Despite the diagnosed extreme-precipitation-based signal, and its possible link to changes in flood patterns, no gauge-based evidence had been found for a climate-driven, globally widespread change in the magnitude/frequency of floods during the last decades.
I find it somewhat difficult to reconcile the three areas I bolded, maybe there's a mixing of estimation and detection going on. That last statement is a thin reed for RPJr though and he's directly contradicted by the parts saying flood mitigation has significant effects on outcomes. He might note that he only referred to "technology" and that building levees isn't a technological change, but that's proof then that he's throwing sand to obscure the flaws in his attempt to normalize damages over time.
A lot of work to refute just one misleading claim. Thanks a lot, Nate Silver.
UPDATE: thought I'd check the RPJr refs for US hurricanes and tornadoes not being mitigated by changes over time, but they're paywalled. Curious that changed practices can reduce Australian tropical cyclone damages but not US hurricanes. Either the Aussies are better at this than us or somebody's wrong.
