The effects of rising oceans on coastal flooding may be even worse than we thought. Scientists have found that a mere 10 to 20 centimeters, or about 4 to 8 inches, of sea-level rise – which is expected by 2050 – will more than double the frequency of serious flooding events in many parts of the globe.

The findings, described in Scientific Reports, highlight the environmental and economic impacts of sea-level rise on coastal areas, and the need to properly predict and prepare for these effects.

High surf crashes into the sea wall at Will Rogers State Beach in Pacific Palisades. Waves can enhance flooding, scientists say. TNS/Al Seib, Los Angeles Times

As global warming marches onward and land-ice reserves continue to melt into the seas – thanks in large part to human-produced greenhouse gases – oceans are continuing their upward creep. Researchers have long made global-scale estimates of sea-level rise and analyzed what effects the ocean’s ascent will have on coastal erosion, on the environment and on human communities. Those estimates have taken into account storm surge and tidal fluctuations, among other variables. But they haven’t included a crucial factor: waves.

Waves might seem like small potatoes compared with high tides, but they can have a big impact, aid Sean Vitousek, a coastal scientist at the University of Illinois at Chicago.

“Waves often generate a pretty significant portion of the actual flood levels,” he explained.

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