Changes in erosion and flooding risk due to long-term and cyclic oceanographic trends

We assess temporal variations in waves and sea level, which are driving factors for beach erosion and coastal flooding in the northern Gulf of Mexico. We find that long-term trends in the relevant variables have caused an increase of ~30% in the erosion/flooding risk since the 1980s. Changes in the wave climate—which have often been ignored in earlier assessments—were at least as important as sea level rise (SLR). In the next decades, SLR will likely become the dominating driver and may in combination with ongoing changes in the wave climate (and depending on the emission scenario) escalate the erosion/flooding risk by up to 300% over the next 30 years. We also find significant changes in the seasonal cycles of sea level and significant wave height, which have in combination caused a considerable increase of the erosion/flooding risk in summer and decrease in winter relative to long-term trends.