Are Sea Levels Rising – You Can Check Using Simple Arithmetic

It is commonly reported that sea levels are going to rise by over a meter in this century. DEFRA in the UK issued predictions in 2006 that sea levels will rise as

Period Rate of Sea Level Rise
mm/year
Total Sea Level Rise
for period in mm
1990-2025 4.0 140
2025-2055 8.5 255
2055-2085 12.0 360
2085-2115 15.0 450
Total 1990 to 2115 1205

A predicted rise of 1.205 meters between 1990 and 2115.

Are the predictions right and does it matter if they are or not?

Well it certainly matters to some people as the Environment Agency are using these projections as the starting point for their Shoreline Management Plan which is how they plan to manage sea walls and the coast line for the next 100 years. The consultation period for this plan has now closed and SMP is awaiting approval DEFRA. There has been opposition to SMP in some communities, including some near to where I live in North Essex, as it was planned to knock holes in the sea wall and let some farm land and communities flood. This process is called managed retreat.

Perhaps its worth a quick check to see if the predictions are reasonable. Fortunately the Permanent Service for Mean Sea Level holds records of observations of sea levels at various sites around the world and this data may be downloaded from www.psmsl.org

Here is the data for Felixstowe


Felixstowe Monthly Sea Levels

And here it is with a trend line and DEFRA projections


projected sea level rise at Felixstowe

The trend line shows sea levels at Felixstowe falling by 0.2mm/year.

You can download a pdf report where I discuss in more detail the sea level rises at 7 locations in the UK. Lowestoft has the largest rise, 2.4 mm/year, here is the data with trend line and DEFRA projections


projected sea level rise at Lowestoft
Do the projections seem reasonable to you?

Why not have a look your self, pick a location from www.psmsl.org and look at the data.

  1. Estimate the rate of sea level rise by printing out a chart (landscape will give you a bigger chart).
  2. Do an eye ball fit, use a ruler to decide the line that best represents the trend of the data.
  3. Choose start and end points on the line.
  4. Estimate the rate of save live rise as

change in sea level between start and end points
number of years between start and end points

That’s right the only maths or arithmetic you need is division. Of course if this is to simple for you could use Excel, R or any other maths package to do linear regression.

If you feel that the DEFRA projections are not reasonable why not lobby your mp, DEFRA and EA. Remember EA is planning to flood some of the UK based on DEFRA’s projections.

 

 

 

 

 

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