Take a Deep Breath and Think Again.
Just when you figured out you had to sell your $6 million shoreside estate and move inland, now comes continued evidence that the rising sea level isn’t the problem we’ve been warned about.
And just when the City of Portsmouth is on the verge of spending millions of taxpayer dollars to protect the development of Prescott Park from these rising waters, the news from the world of science shows that the City has misdiagnosed the problem and risks throwing good money after bad.
That’s the central takeaway from the most recent government data on sea level for the Piscataqua River region. After reviewing this information, we concluded the sea level is rising but ever so slowly: the increase in the past 100 years is less than a foot.
This is barely noticeable and not a good reason to be alarmed. The Christmas Storm flooding was a problem, but the rising sea level was not the culprit. Regarding Prescott Park, the underlying problem (joke intended), is that it is sinking due to its poor soils.
Here are the numbers – Follow the Science!
This map of Portsmouth Harbor shows Portsmouth’s two tidal stations at Seavey Island and at Fort Point. Below this map are the charts from National Oceanic and Atmospheric Administration (NOAA) plotting tidal data for these two tidal stations. 
The vertical axis shows the sea level rise in millimeters and the horizontal axis shows the years and starts in 1920. Remember that 1 millimeter equals 0.04 inches.
For the Fort Point station, the rate of rise is 2.04 millimeters (0.081 inches) per year over the past 100 years. So, 2.04 millimeters per year comes out to only 8.16 inches or 0.67 feet in a century. That’s tiny.
The Sea Level Rise is Slowing
But look at the past twenty years, when we had been told to expect a rapid increase of higher sea levels in our region. This plot suggests that the rate of rise, as shown by the slope of the line, is even less than what existed from the 1920s to the 1960s.
In other words, the rate of sea level rise has slowed during the past half-century, just when we have been told to expect an acceleration.
Let’s look at the Seavey Island station to see if there is disagreement or confirmation of these observations from Fort Point.
Here, the rate of sea level rise is ever-so-slightly higher, at 2.07 millimeters (0.082 inches) per year. This calculates out to 8.2 inches or 0.68 feet of sea level rise over a century. Again, less than a foot in 100 years.
So, the same observations hold true for Seavey Island as were made for Fort Point: sea level rise over the past 100 years is less than a foot. And the rate of sea level rise over the past 20 years seems to have slowed.
Historically speaking, if it takes over 100 years for the local sea level to rise less than a foot, then it’s difficult to blame sea level rising as the culprit for the floods witnessed at Prescott Park or elsewhere along the Seacoast. This is not the basis for alarming predictions. Over the past century, sea level rising in the Piscataqua River area is not a big deal. Don’t sell your house yet!
Parts 2 and 3 will dig deeper into this fascinating story. Hang on to your hats!
