The largest waves in the Pacific Northwest are getting higher by seven centimeters a year, posing an increasing threat to property close to the shore. And the strange part is: Scientists aren't sure why.
"Over a decadal scale, the increases in wave height ... have significant impacts on both erosion hazards and coastal flooding hazards and those currently exceed the influences of sea level rise," said Peter Ruggiero, "And they probably will over the next decade or two unless something drastic happens."
Details at wired.
I bet they need to look for increases in westerly wind strengths or fetches. I don't see a mere increase in sea level as affecting the amplitudes of the waves. It must be an increase in forcing.