What is going to happen to Bull Island? It’s very uncertain but it’s likely to be quite dramatic

When it comes to flooding risk, the Liffey is well-managed upriver but there is an entirely different proposition from city centre out to Dublin Bay.

The capital faces the consequences of living with continuing locked-in sea level rise for centuries, explains coastal flooding expert Dr Gerard McCarthy of Maynooth University – because there is so much “inbuilt heat” from global warming and polar ice sheets continue to melt.

So it’s a question of when a storm surge hits, he says. With every 20 centimetres of sea-level rise, flooding risk increases disproportionately; a one-in-50 year storm becomes a one-in-five year event. Dublin Bay is rising at double the rate of global sea levels.

Picture this: a fierce northerly wind whips up in the Irish Sea. Combined with a high tide, it funnels into the Liffey estuary. So what’s the likely scenario?

‘Dublin Port was very dangerous 300 years ago’: Inside the port that keeps Ireland going

---

The Liffey and Intel: How the river plays a key role in multinational’s operations

---

What is going to happen to Bull Island? It’s very uncertain but it’s likely to be quite dramatic

---

Why is it so hard to find the source of the river Liffey?

---

It could be a 1-metre storm surge rapidly moving inland, hitting the city centre along the quays. “We cannot say how far it will go,” McCarthy adds – in London that point has been determined; Teddington Weir on the Thames.

Fluvial flood risk is reduced on the Liffey because water is well managed using dams, he says, in contrast to the Dodder and Tolka which have given rise to flooding in recent years.

In 2002, 1,000 homes in East Wall and Clontarf were flooded. The Liffey rose by more than one-metre, a record high. Lessons are well learned and Dublin is better able to respond, McCarthy says.

The Climate Change Advisory Council, however, has underlined the need to further strengthen flood defences in cities such as Dublin. “Vulnerable critical infrastructure needs to be made more resilient to climate change so cascading impacts are avoided,” it warned.

Dublin City Council (DCC) has implemented measures to minimise flood risk along the Lower Liffey, notably the Liffey Boardwalk and south campshire defences, with a plan to construct flood defences on the north campshire. About 20,000 properties are at significant flood risk in the city, but most are already protected by flood defences.

“Sea level rise and storm surges are a risk to Dublin city, but not the only risk. Heavy rainfall is also a significant risk. If there was significant downpours of rain over an extended period of time and this combined with very high tides, would create a flooding risk to the city along the Liffey,” a DCC spokeswoman said.

DCC aims to provide improved and “climate adaptable flood defences” in Clontarf and Sandymount in the near future.

A data visualisation devised in 2022 by Cervest climate technology company indicates more than 8,500 buildings are at risk by 2100, including hotels; museums, the financial services district, private property and energy suppliers, notably power stations – concentrated around the mouth of the Liffey. It shows vulnerable locations to an average depth of 1.7 metres ie a mid-range prediction of likely sea-level rise by scientists.

Nature can be used to good effect in reducing flooding in the upper river, says ecologist Padraic Fogarty. As it moves slowly and meanders through Kildare, “flood meadows” can be created but there is uncertainty around the coastal threat and likely impact.

“Climate change is affecting the way ecologists are thinking because we were so sure in the past about what would work [in] restoring nature. If sea level rises by a metre in the estuary. What’s that going to do to our coastline, our habitats? What is it going to do Bull Island? It’s very uncertain but it’s likely to be quite dramatic.”