We use a hydraulic model to translate previously published attribution statements about precipitation during Hurricane Harvey to statements about the resultant flooding and associated damages. We find that while the attributable increase in the total volume of floodwaters is the same as the attributable increase in precipitation, the attributable increase in the total area of the flood is less. However, we also find that in the most heavily flooded parts of Houston, the local attributable increases in flood areas and volume are substantially larger than the increase in total precipitation. The results of this storyline attribution analysis of the Houston flood area are used to make an intuitive best estimate of the cost of Hurricane Harvey attributable to anthropogenic global warming as $13 billion US.
The extent of Hurricane Harvey’s freshwater flood that is attributable to anthropogenic global warming can be quantified and to first order depends on how much of the storm total precipitation over land is similarly attributable. In general, because of the flat topography, over the greater Houston area attributable floodwater volume scales as the attributable precipitation but attributable flood area scales at a lower rate. However, there are substantial differences from one neighborhood to another depending on drainage details. This approach provides a rather direct estimate of the economic costs of climate change and associated environmental justice implications that can be further refined by the considerations of local socioeconomic differences.
Climate change caused significant additional flooding in the Greater Houston area than would have occurred in a non-industrial climate system.