Judging by the reporting on the BBC website, the Welsh coastline is at serious risk of worsening flooding and erosion, caused by climate change, of course.

On 20th September 2019 we were asked, pointedly, “What is climate change doing to Wales?”.i Inevitably, the answer wasn’t pretty:

Alun Williams, cabinet member for carbon management in Ceredigion, said rising sea levels were threatening its flood defences.

The local authority is trying to plan how to manage the effects of climate change along the coast.

Stood on the shingle ridge which acts as a barrier between land and sea at Tanybwlch beach near Aberystwyth, Mr Williams said: “The sea is overtopping this bank much more regularly than it used to – it’s just a matter of time before it breaks through and moves inland.”

Rising sea levels and more frequent storms mean there are fears this defence could soon be breached.

16th July 2021 saw a stark warning:

Climate change: ‘Sleepwalking into oblivion’ coastal erosion warning.ii

0n 28th September 2021 we were toldiii that:

Latest projections show 11.3% of land in Wales will be at risk from flooding from rivers or the sea – a rise from the 9.86% previously predicted.

Minister Julie James said the new advice will help protect communities from the effects of climate change.

“Flood risk and coastal erosion in Wales is increasing as a result of climate change,” she said.

Appropriately, Halloween 2021 saw another scary story, wrapped up in a bigger articleiv about climate change and Wales, its response to it and its threats. Worryingly:

Just under 12,000 properties are at high risk from coastal or river flooding. There are just under 10,000 at high or medium risk of tidal flooding alone.

This could increase by 260% by the 2080s – while 2,126 properties are likely to be at risk of coastal erosion where defences are not maintained.

Less than a fortnight later, on 12th November 2021 we were told that because of “Climate change: Size of Wales may change due to coastal erosion”.v

Clearly there doesn’t need to be any significant new development before a scare story can be repeated (ad nauseam, since this was the time when BBC climate correspondents were breathless with excitement about COP26).

History

And so it came as a bit of a surprise when, on holiday in Snowdonia last month, we visited Harlech Castle, and were confronted by a sign which said:

Today the sea is a long way off, but in 1283 it lapped at the foot of the rock. This meant that Harlech Castle could be supplied from the sea during a siege.

…Where did the sea go? Huge storms in the 14th century led to the build-up of sea dunes, pushing the sea back and creating marshland. The river estuary provided tidal access to the castle until the 17th century. Over time the marshland was reclaimed for farmland; the estuary was lost, and Harlech became landlocked.

Certainly, looking out from the castle, the sea was a good distance away – perhaps as much as half a mile off.

Soon afterwards, we visited Anglesey and took a look at Beaumaris Castle. The situation here isn’t quite so dramatic, but the sea is again some distance away from the castle, at least 200 yards, I would guess. It wasn’t always that way, however. “The gate next-the-sea entrance protected the tidal dock which allowed supply ships to sail right up to the castle.”vi

These mediaeval castles, which were once next to the sea, and are now some distance from it, set me thinking, and then I remembered Caerlaverock Castle, this time in southern Scotland (on the Solway Firth). We visited it a few years ago, and I seemed to remember something similar. A quick internet search confirmed that my recollection was not mistaken:

When built it stood at the head of a tidal inlet at a time when the sea level was higher than it is today.vii

What? Sea levels higher than today? How can this be? Didn’t the hockey stick demonstrate that tales of a Mediaeval Warm Period being warmer than today were nonsense? Aren’t sea-levels inevitably linked to CO2 emissions?

Historical information can be so inconvenient, and so can modern researchviii:

It is now also believed that changes to the coastline caused by “extreme weather events” may have helped push the Maxwells from their home.

Stefan Sagrott, Senior Cultural Resources Advisor at Historic Environment Scotland said: “Working with the University of Stirling, we are undertaking palaeoenvironmental coring and analysis at Caerlaverock Castle to better understand the events which led to the abandonment of the ‘old’ castle in favour of the ‘new’ one.”

The harbour survey will date it for the first time with [sic] it hoped waterlogged artefacts of leather and wood could help tell the story of everyday life at 13th Century Caerlaverock.

Mr Sagrott said: “It is thought that extreme weather events caused gravel ridges to be driven from the sea to the coast, which affected the castles [sic] relationship with the coast, potentially changed the water table and possibly sealed off the harbour as well.

Tidal Gauges

There is a big push to persuade us that climate change is causing stormier weather. The fact that the UK has experienced severe storms throughout its history might go some way towards suggesting that these claims are exaggerated or even plain wrong. However, even if that is the case, rapidly rising sea levels would undoubtedly be a real problem. Anyone with a building on or near the sea might well be in trouble if sea levels rise.

However, this was always the case. Whether due to greenhouse gas emissions and/or other anthropogenic factors, temperatures have been rising globally since the end of the Little Ice Age. Inevitably this must lead to ice melt, and insofar as the melting ice is not sea ice, that must lead to rising sea levels. So the problem of coastal erosion and rising sea levels is not new. It only becomes an issue, which can fairly be attributed to climate change, if the rate of sea level rise is accelerating.

Fortunately there are some fairly comprehensive records available on-line which we can study with a view to ascertaining what trends there might be with regard to sea level rise. The National Tidal and Sea Level Facility websiteix contains data for 49 locations around the UK coast, from Aberdeen to Workington, from Belfast to Whitby.

I have spent some time eye-balling these charts, and I cannot discern an accelerating trend in any of them. Admittedly, it may in some cases be that the land is rising (isostatic rebound following the last ice age seems to be generally accepted as a real phenomenon), and this might distort the extent to which sea level rise appears to be a problem, though I can’t see that it would distort the gauge readings.

In any event, the readings from the Welsh tidal gauges don’t seem to justify the hysteria on the BBC website. Perhaps I would feel differently if I lived very close to the coast.

Conclusion

The question of sea level rise relative to land is complex. As Wikipedia puts itx:

As well as the addition of melted ice water from glaciers and ice sheets, recent sea level changes are affected by the thermal expansion of sea water due to global warming, sea level change due to deglaciation of the last glacial maximum (postglacial sea level change), deformation of the land and ocean floor and other factors. Thus, to understand global warming from sea level change, one must be able to separate all these factors, especially postglacial rebound, since it is one of the leading factors.

In short, hysterical claims about climate change, rising sea levels and erosion, do little justice to a complex subject, and ignore an awful lot of inconvenient history.

Endnotes

i https://www.bbc.co.uk/news/uk-wales-49753740

ii https://www.bbc.co.uk/news/uk-wales-57852719

iii https://www.bbc.co.uk/news/uk-wales-58711041

iv https://www.bbc.co.uk/news/uk-wales-58706283

v https://www.bbc.co.uk/news/uk-wales-59223819

vi http://www.beaumaris.com/index.html

vii https://www.transceltic.com/scotland/caerlaverock-castle

viii https://www.scotsman.com/heritage-and-retro/heritage/story-of-scottish-castle-that-vanished-750-years-ago-to-be-unearthed-3301811

ix https://ntslf.org/products/sea-level-trend-charts

x https://en.wikipedia.org/wiki/Post-glacial_rebound

10 Comments

  1. The 1287 storms that may have done for Dunwich by washing it away may have done for New Romney by silting it up. This wiki is about the first of the two: https://en.wikipedia.org/wiki/South_England_flood_of_February_1287

    English Heritage’s mapping out of the known knowns and known unknowns of (English) Medieval seafaring and ports is a rather good summary: https://researchframeworks.org/maritime/high-to-post-medieval-1000-to-1650/

    The process of coastal erosion and accretion, especially on soft coasts, is a fascinating topic. The lack of a historical perspective is something that often seems to get alarmists hot under the collar. Would the 1287 storms be enlisted as propaganda in the climate wars if they occurred today?

    Liked by 1 person

  2. Of course building up scare stories of future flooding can get you a lot of money you need not spend on flood defence !!??

    Like

  3. Storms and disappearing land are nothing new. They seem to have had a bad time of it during the MWP. From Ann Lingard’s book, “The Fresh and the Salt”, page 110:

    “Some time between August 1301 and April 1304 there was a mighty storm and the port and part of the village of Skinburness was washed away.”

    Like

  4. Norfolk will soon be Norfol as the relentless erosion of its soft cliff lines gathers pace, regardless of any isostatic rebound. A favourite bench of mine overlooking the sea has long gone.

    I last visited Harlech Castle in the early 1960s (taking a day off geological mapping). It was impressive then. I wonder if the sea has continued to retreat or if it is advancing.

    Like

  5. Alan, indeed Norfolk does have a big problem with regard to coastal erosion, but it’s nothing new, and to that extent is not down to “climate change”. This website offers a quick summary of the state of play:

    https://www.countryfile.com/go-outdoors/historic-places/britains-abandoned-coastal-villages/

    Among others:

    “Coastal flooding and erosion had destroyed most of the Norfolk village of Eccles by the turn of the 17th century. After a serious flood in 1604, the village was left with just fourteen houses, and flooding in 1895 destroyed the church tower.

    The Norfolk coast is infamous for being one of the fastest eroding coastlines in Europe, because of a mix of soft clay and the battering waves of the North Sea. Along the coast, a number of villages have been abandoned or lost due to the power of the sea. Local records suggest the villages of Clare and Foulness succumbed to erosion in the 15th century, while other villages lost include Ness, Keswick, Newton, Shipden and Waxham Parva.”

    And a little further south, there’s this:

    “The village of Dunwich still stands a few miles from Southwold, on the Suffolk coast, but it used to be a much larger town. In the 11th century, it had a large port, a naval base, two seats in parliament and one-sixth of the population of London.

    Unfortunately, the coastline in which it stands is one of the fastest eroding in Europe. Couple this with a storm surge in 1286, and two ‘great storms’ the following year, and the decline was sealed.”

    Much further north, there’s this:

    “Much like Dunwich, the Aberdeenshire village of Rattray lost the battle against shifting sands. A storm in the 18th century covered the village in sand from nearby Rattray Head.”

    Less further north, there’s this:

    “Much like the Norfolk villages that were lost to the sea, Ravenser Odd, at the mouth of the Humber, was prone to coastal erosion.

    At one time, the town was a thriving seaport, and deemed more important than Hull. Numerous cargo ships and fishing boats called the town home, and at its peak, it was of national importance because of its regular supply of ships to the king. The town was even mentioned by Shakespeare’s character Richard II.

    By the middle of the 14th century, Ravenser Odd had been completely destroyed by the sea’s powerful erosion. Reports from 1346 suggest that a large majority of the town had gone, and it was essentially non-existent by the 1360s, having been destroyed by the ferocious Grote Mandrenke storm.”

    And further south west, there’s this:

    “Winchelsea, near Hastings on the East Sussex coast, has been effectively lost not once, but twice. Old Winchelsea was a fairly important town in the 13th century, with trade links to northern France and its wine regions. Records show that there were over 700 houses and a plethora of inns and taverns around this time, suggesting a population of a couple of thousand people.

    Throughout the century, the sea was a common problem for the residents of Winchelsea, and in 1287 much of the town was destroyed after a large flood. The town was rebuilt very close to the original location, with a tidal harbour, which was overcome by silt in the 16th century. “

    Like

  6. The subject of isostatic rebound is, I think, fascinating. Please indulge me while I quote at some length from Ann Lingard’s book, which I mentioned in a comment above (its focus is the Solway Firth – indeed its sub-title is “The Story of the Solway”):

    “But glaciers are weighty masses of ice and rock and, as they melt, the land is released and it ‘rebounds’, rising out of the sea. Professor David Smith, Visiting Professor at Oxford University’s Centre for the Environment, and his colleagues from the University of Coventry, have extensively researched sea levels in the Solway as part of a European study into the effects of sea-level rise. David told me that ‘The subsequent story is one of competition between rising sea and rising land, with both slowing in rate towards the present – the changes becoming progressively more subtle.’ This subtlety and complexity has characterised the development of the Solway Firth, as David and his colleagues found during their fieldwork along the Scottish coast. Large deltas from the retreating ice are present in the Nith and Lochar Water valleys, with marine terraces along their seaward margins. Such terraces can be found throughout the Scottish Solway coastline, at heights of 20 to 25m above Ordnance Datum. Then, the Firth would have been very much wider, reaching far inland to meet the torrents of meltwater that would have raced down from the ice on all sides…

    “Land uplift now increased and outpaced the rising seas so that the Solway would have become narrower and more shallow. David says its extent at this time is unknown, though he thinks it would have remained a major estuary. But then, by 12900 years BP, the Earth’s climate cooled again and the rise in sea level slowed or stopped as small ice caps developed during the Loch Lomond Readvance. Glaciers developed in the Galloway Forest Park area and in the Lake District. But the dance continued: renewed warming of the climate caused these new glaciers to melt and sea-level rose, initially outpacing the isostatic rebound of land. However, the land eventually gained supremacy, and the old shorelines were left ‘high and dry’ – so we see the gravelly lines of raised beaches in the Allonby dunes, and the marine terraces and ‘fossil barriers’ of pebbles at different heights along the edges of the estuaries of the rivers Nith and Cree….”

    The story goes on, at too great a length to copy here, of rising and falling sea levels. There are the remains of a forest out in the Solway still. The story of sea-level changes is a lot more complex than just “Ooh climate change, we’re doomed”.

    Like

  7. Adding to the complexity of climate change impacting the UK are interesting studies by G. Bromley et al. regarding their findings that the island kingdom can shift from a mild maritime climate to more extreme seasonality like inland continental places. Carbon dating analyses showed that the last glacier there retreated during the chilly Younger Dryas, suggesting that the climate had both cold winters and hot summers concurrently. Bromley’s paper is Interstadial Rise and Younger Dryas Demise of Scotland’s Last Ice Fields
    https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2018PA003341

    My synopsis:

    Concurrent Warming and Cooling

    Like

  8. We have lived on the south side of Morecambe Bay for 34 years now and have noticed little in the way of sea level rise. The salt marsh comes and goes and then comes back again, eroding on the south side of the bay and growing on the north then vice versa every 20 years or so, depending on the river channels flowing in to the bay. The original IPCC predictions of a metre rise in sea level by the end of this century means we should have seen a 20 – 30cm rise by now. My hunch is that were this the case, the salt marsh would be covered more frequently at high tides, and it’s not. Anyway, the skylarks don’t seem unduly bothered, they are still singing and ascending and presumably nesting on the marsh!
    The high tide ranges between 7.5 metres and 10 metres. Higher with a spring tide and a low pressure, of course. A 10m tide is always of interest as it will flood some of the coastal roads but in 30 plus years of living here, we haven’t noticed any significant increase in the number of days when the roads are unpassable.
    But what do I know……!

    Like

  9. Mark. The quotations from Ann Lingard’s book bring back some of geology’s early fascination for me. How you can stand within a landscape, look around, and with instruction and perseverance begin to unravel momentous changes, like the disappearance of mighty cliffs of ice, seas retreating or returning with redoubled interest, destroying or rearranging everything. Then there are quieter interludes when dunes grow and move around and alluvium accumulates as water meadows. National parks (GB, USA, Canada, some in Europe and Australia) have put up explanatory boards that can bring your surroundings to life and make a visit so much more worth while. I have been very appreciative.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.