“The coastal road being eroded by climate change” says the BBC article. No ifs. No buts. Not simple ongoing erosion. Climate change is apparently unequivocally to blame for the fact that the B3191, known locally as Cleeve Hill, near Watchet in Somerset, was closed to traffic due to dangers from coastal erosion.

I’ve got to give it to the BBC – they’re clever. They push the climate change angle with a forthright headline, but apparently it’s not the BBC blaming climate change for the pending demise of this section of the B3191. Oh no indeed. It’s not them, it’s experts – in this case, “the independent firm Geckoella, which has been advising Somerset Council on what is happening on the West Somerset coastline.”

Dr [Andy] King [a director of Geckoella, during an interview with BBC Radio Somerset] laid the issue squarely with climate change, calling the rate of erosion there “unprecedented”.

He said the impact of climate change was not only the raised sea levels, but an increase in persistent rainfall in the area, meaning coastal erosion was getting worse.

That’s pretty definite. No need for a BBC fact-check or any investigation of such claims by BBC Verify? Of course not. So it’s down to me again. Here goes.

According to the website of Dr King’s organisation:

Like many UK coastal sites, the Watchet coastline is subject to continuous tidal erosion (with the 2nd largest tidal range in the world) and complex hydrological systems within the cliffs themselves. As a result, cliff subsidence, rock falls and landslides are a regular, and expected occurrence. Additionally, the effects of global climate change are expected to cause sea level rise, and accelerate coastal erosion processes in the future.

Which is rather different from the stark claim made in the BBC article. Here we learn that the effects of climate change are only an additional factor that is expected to accelerate existing coastal erosion processes in the future. There is no mention of the problem being caused by climate change now. Amusingly, though, Geockella’s website does treat us to a geological history lesson:

Looking in detail, the rocks at Watchet record a dynamic time in Somerset, and the Earth’s history. The red triassic rocks were laid down in a hot, semi-arid environment around 210 million years ago, during this time, Watchet was closer to the equator and part of the supercontinent Pangaea. The Triassic Period ended with a mass extinction, giving rise to the ‘age of the Dinosaurs’ in the Jurassic. The Jurassic rocks at Watchet were laid down in a marine environment as sea levels rose around 200 million years ago – these rocks contain abundant ammonites, crinoids, bivalves and fossil wood.

Now that’s what I call climate change!

What of the specific claims apparently made by Dr King during his radio interview? Well, Hinkley Point isn’t too far up the coast. The River Levels website tells us this:

The usual range of the Tide at Hinkley Point is between -5.38m and 6.46m. It has been between these levels for 90% of the time since monitoring began.

The typical recent level of the Tide at Hinkley Point over the past 12 months has been between -5.87m and 11.84m. It has been between these levels for at least 150 days in the past year.

The highest level ever recorded at the Tide at Hinkley Point is 7.45m, reached on Friday 3rd January 2014 at 8:00am.

Even better is the information regarding the Washford River, which actually flows through Watchet:

The usual range of the Washford River at Beggearn Huish is between 0.15m and 0.50m. It has been between these levels for 90% of the time since monitoring began.

The typical recent level of the Washford River at Beggearn Huish over the past 12 months has been between 0.17m and 0.59m. It has been between these levels for at least 150 days in the past year.

The highest level ever recorded at the Washford River at Beggearn Huish is 1.05m, reached on Thursday 7th December 2000 at 8:45pm.

And here’s a link to a chart for sea levels at Newlyn, supplied by the National Tidal and Sea Level Facility (NTSLF). It is, I think, of direct relevance, because it’s in the south west of England, and as the NTSLF website tells us, it (and Aberdeen) “have some of the longer data sets of hourly (or 15-minute) sea level data”. Please click on the link and look long and hard at the graph. If you can see an accelerating rate of sea level rise, please tell me in a comment below, because if there is such a trend, I can’t see it.

I will accept that this isn’t definitive, but it’s reasonably strong evidence that sea level rise isn’t accelerating on the Somerset coast. And given that sea levels have risen steadily as the world emerged from the Little Ice Age, only an accelerating rate of sea level rise would be evidence of current man-made climate change.

Well then, what of the “increase in persistent rainfall in the area” referred to by Dr King? The best I have been able to do here is to check the long-term data made available by the UK Met Office for Minehead, which is a short distance along the coast from Watchet. It may (or may not) be that “persistent” rainfall is increasing, but it is difficult to establish from the data. The information available from the Met Office is monthly and annual rainfall levels, and also average numbers of days (per month and annually) with rainfall at or above 1mm per day, which while better than nothing, doesn’t tell us much about “persistent” rainfall. I accept that in the south of England especially, a pretty wet year to 18 months have just been endured, but such a short time scale represents weather, not climate. For climatic trends, I have analysed the data over varying 30 year periods, namely 1961-90; 1971-2000; 1981-2010; and 1991-2020. Admittedly the data shows a slowly (certainly not dramatically) rising trend in the average number of days per annum when 1mm or rain fell – from 130.94 in the earliest period, to 141.44 in the latest period. Volumes increase over the same period from 840.72mm to 896.61mm, representing an increase of a little over 2” per annum over 40 years. How might that feed into claims of increasingly persistent rainfall? On a rough and ready basis, it might suggest that there has been no increase in rainfall persistence at all. If one assumes that the days of persistent rainfall are those when 1mm or more of rain falls, then allowing for the increase in the number of such days, the difference in daily rainfall on such days over the period is statistically insignificant, falling from 6.42mm to 6.40mm per day.

Although it wasn’t mentioned in the BBC article (and I assume therefore wasn’t mentioned either during Dr King’s radio interview) if there was an increase in storm numbers or intensity, that might be a valid reason to claim that the erosion at Watchet is being caused by climate change. However, I mention it only to dismiss it as an an argument, for as I mentioned in Whatever the Weather the annual Met Office reports on the UK’s weather continue to state categorically that no increase in storminess is being observed.

Geckoella’s work looks fascinating, and I wish them well. However, I don’t think Dr King’s claims relating to climate change at Watchet, as reported by the BBC, stack up. No doubt the BBC was delighted to have elicited the comments in it did during a local radio station interview, but I believe it was incumbent on them to dig a little deeper before proceeding with a sensationalist and alarmist headline that so far as I can see is not borne out by the facts.