Not only were atmospheric rivers the primary driver across all 11 states, with annual average damages of $1.1 billion, but they also caused over 95% and even exceeded 99% of flood damages in some coastal areas of northern California and the Pacific Northwest.
In addition, the authors used a recently developed atmospheric rivers intensity and duration scale varying from 1 (weak) to 5 (exceptional) to assess how flood damages change with each category. They found that each increase in the atmospheric intensity and duration scale corresponds to a roughly 10-fold increase in flood damages. Flood damages from atmospheric rivers are expected to increase in the face of rising population, increased development, and climate change.