Sea level ‘n all that – better watch your toes and have dry socks handy!

I don’t know about you, but sea level gets me worried for my descendants if not for myself. Now its easy to look at the sea, and the big waves, or the small ones, or wavelets on a flat calm day, and wonder “why all the fuss?” Surely its just the sea? Same old, same old.

Well my career led me to close encounters with sea levels – not so much present ones, still less with future ones, but OLD ones. That sea is nothing like as stable as the public likes to image. All the talk is about FUTURE sea level, but nobody says much about the old ones. I admit -its hard to step out and see climate change. Of course there is plenty of writing about it – failed civilizations, here, there and everywhere – no Continent excluded, except perhaps Australia & Antarctica. Some were due to drastic changes in climate, others happened perhaps because of failures in the socio-political system. Any number of reasons can be given. But rarely is sea level mentioned, unless you are into Atlantis, and depending where you think it was. Sea level, in one sense, doesn’t help itself. A fact known by all geoscientists concerned with the last few million years is that present sea level, leaving aside local blips, for local reasons, reached its present elevation about 5,000 years ago (BP, Before Present in tech terms). About twice that time ago the level was about 100 m (330 feet) lower (speaking in approximate terms). SO, OF COURSE, (almost) everyone in that older time period lived down by the sea, and what is more, after a long period of stable low sea levels during the last episode of the Ice Age, they had to adjust to its constantly rising level as the world’s great Ice sheets melted – mainly those in North America and Western Europe. Even cities, built out of its reach as they thought at the time, got swallowed up and submerged. Alas there were no pundits then with insider information on why it was happening. Hence, innumerable myths about lost civilizations were borne, most of them myth-smothered realities. But what about the last Interglacial, when conditions – some of the time – were not unlike those at present, give or take a sabre-toothed tiger or mastodon? Well some of that time sea level was close to present, and even a few metres above it because it was warmer then (but not because of early H. sapiens’ cooking hearths). And if you had been around it would have looked just like the present, probably with the self-same clams for lunch.

zzzzzzz   ……..  CUT to the PRESENT —  KABOOM !!!!!

Here, from a site on the west coast of the Isle of Man is what it looks like now at low tide, and what is left of what it was like there then.

LastInterglacialSealevel That gently sloping top – is what is left of the old Iast Interglacial shore platform – the bare rocky section below it – covered by water at high tide at present is the modern shore platform. The vertical difference is about 5 metres – roughly the amount I have recently seen was given as the upper limit of the contemporary carbon-fuelled  rise, possible within 200 years. A one-floor cottage on the modern platform would be about that high – and TOTALLY under water. You would still see that last Interglacial platform, just, at low water in 2200 AD. There is nothing that special about this view, except that it is carved into moderately resistant rock so that we can see what has happened. Bigger and better examples can be seen on most rocky coastlines. Occasionally they get a Parks sign saying so.

I’m just trying to keep your feet dry !! Don’t shoot the messenger, and be careful where you put the cottage.


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