When all the ice melts

Pan fydd yr holl iâ’n toddi, bydd y môr yn cyrraedd fan hyn
When all the ice melts, the sea will be up to here

when all the ice melts …

When all the ice on earth melts, the average level of the sea will be around 200 feet higher than it is now.

It will take thousands of years for the sea to deepen by 200 feet (which it will if the Earth’s temperature continues to increase). About five thousand years seems to be the timescale.

Five thousand years, you say? Way too big a stretch of time to think about. But there were people like you and me living five thousand years ago, with writing and money and organised religion and civil engineering and agriculture and beautiful art.

Think of a 200-foot depth of water inching its way upward, slowly, relentlessly deepening field drains and great rivers alike. I live beside the sea, and this is what I’ve been thinking about recently. Indeed, I live next to a large swathe of low-lying land that was sea until around two hundred years ago, until the Cob was built at Porthmadog.

cofiwch cantre’r gwaelod

In 2019 the Extinction Rebellion Cymru banner at the head of this post was positioned on the Cob. In the Welsh language ‘Cofiwch’ is the command ‘Remember’. Remember the submerged land of Cantre’r Gwaelod, which, according to legend, is now under the waters of Cardigan Bay. The earliest version of this story is in the Medieval Black Book of Carmarthen – Cantre’r Gwaelod is a vivid and deep part of the Welsh psyche.

My project

In autumn 2021, I started cycling and walking (and occasionally bussing it) to points near me where roads and public rights of way cross the 200-foot contour, and pinning up a Post-it note saying:

Pan fydd yr holl iâ’n toddi, bydd y môr yn cyrraedd fan hyn.
When all the ice melts, the sea will be up to here.

It is the thing I have been mostly writing lately. Over and over. Here is a map showing locations where this message has been placed, September 2021–April 2023.

the photos

Every Post-it note I’ve placed has been photographed in situ. The longest river where I’ve left messages along its catchment is Afon Glaslyn, which rises on Yr Wyddfa (Snowdon). The most inland point where the 200-foot contour of its catchment intersects with a point of public access is at the A498 road, here –

in Nantgwynant – near the start of the Watkin Path up Yr Wyddfa. That’s a long way inland.

All the photos can be seen by clicking on the links below. They are grouped by the watercourse that will grow deeper with the rising sea level. The list is arranged west to east, with the longer rivers divided into sections.

Afon Dwyfor
Field drains, un-named on OS maps
Nant y Wyddan and Ffrwd y Brain
Afon Glaslyn, where currently tidal, up to Pont Croesor – Nant yr Afon-oer and Afon Rhyd /Afon Caseg join Afon Glaslyn in this stretch
Afon Glaslyn, from Pont Croesor to Pont Aberglaslyn – Nanmor joins Afon Glaslyn in this stretch
Afon Glaslyn, from Pont Aberglaslyn to Pont Bethania – Afon Colwyn joins Afon Glaslyn in this stretch
Afon Glaslyn in Nantgwynant, inland from Pont Bethania
Afon Dwyryd, where currently tidal, up to Pont Maentwrog – Nant yr Efail and Afon Prysor join Afon Dwyryd in this stretch
Afon Dwyryd, inland from Pont Maentwrog – Afon Teigl joins Afon Dwyryd in this stretch

In each of the photos there’s a Post-it note pinned to something, saying the same thing:

*Pan fydd yr holl iâ’n toddi, bydd y môr yn cyrraedd fan hyn.***

When all the ice melts, the sea will be up to here.

other art prompted by rising sea level

It turns out the same impetus that sends me out with Post-it notes and drawing pins has stimulated other pieces of art – on much grander scales. There is this one, in Còmhghall in Scotland, so I guess I should also say:

Nuair a leagh an deigh uile, bidh uisge na mara suas chun na h-àirde seo.

And there is also this one, The (Future) Wales Coast Path, which is taking place in Newport and Magor in South Wales throughout 2022.

useful information

This is a useful interactive map to look at the result of different heights of sea level rise. For +200 feet, use a rise of 61 metres.

As at March 2022, both the Arctic and Antarctic are vastly warmer than they should be for the time of year, and in the Antarctic the 1,200 square kilometre Conger ice shelf has collapsed. New research, published in April 2023, shows that ice sheets are capable of retreating in bursts of up to 600 metres per day.

This series of short BBC podcasts explores different tipping points in climate change, including in relation to the Arctic, the Antarctic, and ocean circulation.