Thursday, December 29, 2022

How bad is the sea level rise scenario? It could hardly be worse.

The sea level rise issue in Hawai’i is getting worse, and it’s moving toward apocalyptic in a state that depends on its shorelines.

The risk varies around the country—higher on the East Coast than the West Coast and Hawai’i, but nevertheless scary high everywhere.

“Without additional risk-reduction measures, U.S. coastal infrastructure, communities, and ecosystems will face significant consequences,” says a National Ocean Service report.

It is no surprise our beaches are at risk and disappearing. Sea level is now rising at an inch every eight years. 

That means sea levels are now five inches higher than they were when a 40-year-old was born.

And since beach slopes are so low, five inches vertically can mean those beaches erode many dozens of feet inland. We’ve seen that.

It explains houses falling into the water in several Hawai’i locations. Why beach parks are shrinking. Why your beach walks, which used to be on dry sand, are ankle-deep at high tide and you’re dodging sandbags. Why some coastal features, including low-lying roads and harbor piers, are under water at high tide.

As time goes on, and older high-risk scenarios are confirmed, the more hopeful scenarios are necessarily being abandoned.

The sea level is not only rising fast, but it is rising even faster over time. It is now rising at more than twice the average rate during the 1900s. And the increase has continued and is likely to continue further.

You can review the latest data yourself at the 2022 Sea Level Rise Technical Report of NOAA’s National Ocean Service. 

It estimates Hawai’i sea levels in 30 years to be a little less than a foot higher than now. On a beach sloping at 1 percent, that means dozens to approaching 100 more feet of inland migration.

On highways that now get wave-washed at highest tides, it means erosion forces will be dramatic.

We could lose lateral coastal travel in some areas on several islands. Several Hawai’i coastal roads have already lost one of their two lanes due to eroded shores.

The technical report predicts that damaging high tide flooding will occur quarterly and monthly high tide flooding almost monthly.

It means that if you’re building anything on an eroding shoreline today, it’s unlikely to survive through the life of a 30-year mortgage without significant shoreline hardening.

“Sea level rise driven by global climate change is a clear and present risk to the United States, now and for the foreseeable future,” the report says.

© Jan TenBruggencate 2022 

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