Once-in-a-century coastal floods now strike about once a decade, studies find

Extreme coastal flooding events that historically occurred once per century are now striking roughly once every ten years, according to a study published June 10 in Nature Climate Change. Human-driven climate change has quadrupled the frequency of coastal sea level extremes since 1900, the analysis found. A separate study in Science Advances determined that human-caused sea level rise was detectable at 97% of sites sampled worldwide and accounted for approximately 58% of observed daily extreme water level exceedances between 2000 and 2018. Sönke Dangendorf, lead author of the Nature Climate Change study and associate professor at Tulane University, said the investigations rely on observations from tide gauges, but noted that gauges with century-scale records are sparse, numbering just over 100 worldwide since the early 20th century. Climate models fill the gaps and produce future projections. The findings indicate that storm surges, high tides, and rising sea level anomalies, all amplified by human activity, are the primary drivers behind the surge in coastal flood frequency, threatening communities that will only grow more vulnerable as climate change intensifies.