Another Life: Predicting the impact of storms on our west coast beaches

Michael Viney: Could half of Earth’s sandy beaches be extinct by the end of the century?

Andrew Cooper is one of a growing number of scientists for whom the impact of storms on the beaches of our west coast could hold lessons for the wider shores of Europe. Illustration: Michael Viney

Andrew Cooper is one of a growing number of scientists for whom the impact of storms on the beaches of our west coast could hold lessons for the wider shores of Europe. Illustration: Michael Viney

 

A calm summer leaves the ocean lapping gently at the shore. The slow return of sand stolen last winter leaves a new, soft fringe at the edge of the waves, where footprints sink deeper.

All this seems pretty timeless, depending on how in tune you are with life as it is. The trouble today is that you live in one familiar sense of the world, the one you were born to, while the other hovers offshore, like the banks of sea fog that come stealing in at night from a warming, evaporating ocean.

As climate change gathers pace, with its sudden eruptions of fire and flood, even scientists must cope with this duality – the slow, even routine, exploration of the world as it is, and the modelling of change as it might suddenly become.

Take the future of the world’s sandy beaches.

In Nature Climate Change last year, a team of European scientists suggested that, based on the way sea level and storminess are heading, half the sandy beaches of the planet could become extinct by the end of the century.

This brought a strong rebuttal from international scientists who reexamined the data. While sandy beaches below cliffs and seawalls might indeed be scoured away, those backed by low-lying coastal plains, shallow lagoons, salt marshes and dunes have potential to move landwards, if at a new, raised level.

Coastal studies

Lead author of the new paper was Andrew Cooper, professor of coastal studies at Ulster University. Without a lot more information, he argued, it was impossible to categorise the fate of the world’s sandy beaches. “New methods are needed,” he wrote, “for predicting sea level rise on the coasts.”

Cooper is one of a growing number of scientists in Ireland and the UK for whom the impact of storms on the beaches of our west coast could hold lessons for the wider shores of Europe.

A key paper, written in 2008 by Robert Devoy, professor of geography at UCC’s Coastal and Marine Resources Centre, was relatively reassuring, at least for the immediate future. Much of our coast, as he described, already has high resilience, conditioned to the battering of extreme tides, frequent storms and heavy rainfall.

But to fully grasp what climate change will do to Irish landscapes, says Devoy, it is necessary to understand the complexity that drives the variability within their systems. Between climate, hydrology, geomorphology, biology, biogeochemistry, geology and ecology, one small change, or tipping point in one system can ramify, sometimes irreversibly, through many others.

Achill Island

This explains the elaborate mix of research for the Environmental Protection Agency. It engaged nine assorted university scientists for two years to monitor everything about a strand, its dunes and hinterland on the northern shore of Achill Island in Co Mayo. Most came from NUI Galway, teamed with specialists from TCD, UCC and DCU. They had “state-of the-art technology” and 10 willing students to help deploy it.

Achill’s Golden Strand is much like the one below me – a wide triangle of sand between two prominent headlands, with a small river running through it. The strand is backed by dunes, a flat lawn of machair with an SPA protection order, and small, peaty lakes that help to feed an unnamed stream.

Such strands on the Wild Atlantic Way are “attuned” to high-energy storms. The sand dragged away in winter is held offshore, then returned in fair weather.

With a time-lapse camera to watch the flow of daylight tides, the Golden Strand was assaulted by 17 storms during the study, all during spring tides and lasting from 12 to 102 hours. They all came from the same direction and, to quote the EPA Report 376, the strand “seems to have been largely insensitive” to their impact.

The study secured a mass of baseline data on the anatomy of dunes and shore. It explored the inner veins of moisture and salinity that govern the dunes’ stability, the flows of sediment inherited from the grinding of glaciers, the ecology of the rare, protected machair.

Since this was baseline stuff, they called for multi-decadal monitoring and for modelling that leads beyond the measuring of change to predictions of its stormy consequences.

Extreme storms

In a 2018 paper, Andrew Cooper wrote of storms in northwest Ireland becoming more frequent, intense and energetic over the past 67 winters. But he has already argued that beaches and dunes exposed to frequent, high-energy waves require extreme storms to suffer much damage.

The implications, he finds, “are not immediate”, given the long-worn resilience of the coastline. When clustered in groups in consecutive years and varying in direction, however, the future storms can “extend recovery times” of strands and increase erosion.

“As sea level rises,” he told Science Daily, “shoreline retreat must and will happen but beaches will survive. The biggest threat to the continued existence of beaches is coastal defence structures that limit their ability to migrate.”

Nothing too similar, one has to hope, will befall too many peoples of the planet.

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