Sea Level Changes At Newlyn

By Paul Homewood

 

 

We are continuing our tour around the UK coastline to look at how sea levels are changing. We have already checked out North Shields and seen that sea levels there have been rising at 188mm per century, at a pretty constant rate and without any recent acceleration.

Today we will look at Newlyn in Cornwall. First, let’s look again at the map of isostatic rebound.

 

 

Rates of Isostatic Rebound in Great Britain (in mm/yr)

 

The South and East of the country is gradually sinking as the North and West rises as a result of the melting of the ice age glaciers. Newlyn lies close to Lands End, at the South West tip of England, where the rate of sinking is 1.1mm p.a., so we would expect sea levels to be rising faster than at North Shields, where the isostatic rebound is about neutral.

Figure 1 shows sea levels since the records started in 1916.

 

Figure 1

Since 1916, sea levels have risen from 6974 to 7157, an increase of 183mm or about 196mm per century. In theory, 1.1mm year or 110mm per century is due to isostatic changes, leaving 86mm as the eustatic change (e.g. melting ice caps and thermal expansion). The 10 year running average is running close to the long term trend (green line) after a slow down in the 70’s and 80’s.

Figure 2 allows us to zoom in on the annual changes.

 

Figure 2

 

And we can focus just on the 10 year average of these changes in Figure 3.

 

 

Figure 3

The red line on the final graph, by the way, is the trend, not the mean (which would appear to be almost identical). Sea levels have risen faster in the last decade, but probably need to be taken in context with the 1990’s, when they actually fell.

As with North Shields, the message is clear – The rate of sea level rise is not increasing.

 

Full sea level is available at the PSMSL website here.