Excerpts of the Business Insider article by Aylin Woodward

Hawaii’s iconic Waikiki Beach could be engulfed by the ocean in 20 years — here’s the plan to save it

In May 2017, high tides engulfed parts of the iconic Waikiki beach, edging dangerously close to waterfront hotels. This kind of high-tide flooding, often called a king tide or sunny-day flood, occurs when ocean water surges to higher levels than coastal infrastructure was designed to accommodate. In that case, water levels rose 2.5 feet above average in Waikiki, drowning nearby roads and sidewalks.

According to a 2017 report (which was updated in September 2018), Hawaii’s state capital and Waikiki Beach – along with other coastal strips on Hawaii’s five islands – are expected to experience frequent flooding within 15 to 20 years.

“This flooding will threaten $5 billion of taxable real estate; flood nearly 30 miles of roadway; and impact pedestrians, commercial and recreation activities, tourism, transportation, and infrastructure,” Shellie Habel, lead author of the 2017 study, said in a release.

Now, Hawaii state lawmakers are taking steps to shore up the state’s beaches and coastal cities. A new bill that mandates a statewide shore protection program has passed both houses of Hawaii’s state legislature, and will soon makes its way to the governor’s desk for approval.

All well and good that they want to improve beach resilience. But, the claim that ” Hawaii’s iconic Waikiki Beach could be engulfed by the ocean in 20 years ” is totally bogus.

Here is why:

First, lets look at real world data (as opposed to model projections).

Source:

https://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?id=1612340

According to the official NOAA data, there is a 1.49mm per year sea level trend extending back to the year 1900.

According to elevation data via Google Earth the top of Waikiki Beach is about 8 feet above the mean sea level there.

8 feet = 2438.4 milimeters

…at a rise rate of 1.49mm/year based on the NOAA sea level rise rate we have:

2438.4 mm / 1.49 mm/year = 1636.5 years

In 20 years, sea level would have advanced only

1.49 mm/year x 20 years = 29.8 mm or 0.098 feet

Once again, reporters can’t do basic math, but they sure can exaggerate.

Next, let’s look at the 2017 Report they cited as “having passed peer review”, from the methodology section:

Modeling, using the best available data and methods, was conducted to determine the potential future exposure of each island to multiple coastal hazards as a result of sea level rise. Three chronic flooding hazards were modeled: passive “bathtub” flooding, annual high wave flooding, and coastal erosion. The footprints of these three hazards were combined to define the projected extent of chronic flooding due to sea level rise, called the sea level rise exposure area (SLR-XA). Not all hazards were modeled for each island due to limited historical information and geospatial data. Each of these hazards were modeled for four future sea level rise scenarios: 0.5 feet, 1.1 feet, 2.0 feet and 3.2 feet based on the upper end of the IPCC, Assessment Report 5, representative concentration pathway 8.5, or “business as usual” sea level rise scenario.

Even with 3.2 feet of projected sea level rise, the threat when viewed in terms of real-world data is many years away:

3.2 feet = 975.36mm 975.36mm/1.49 mm/yr = 654.6 years.

As anybody in the climate business knows, RCP8.5 is a ridiculous “worse than worst case” climate model that has no real-world counterpart. Only politicians and low information journalists give it any credence.

The follow of this entire thing is that they’d rather look at model data, than the real-world data. But then again, you can’t get grants for stuff that will happen 600 to 1000 years in the future, can you?

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