They put it down to unusually heavy rain, coinciding with unusually high tides. An unfortunate event. A once-in-a-century-occurrence.

But many experts warned that the floods were a result of global warming. And that from now on we could expect more floods, more frequently. After years of gloomy predictions, they said, the climate had finally started to change.

"While you can't attribute climate change to any one occurrence, these events are exactly what we would expect to happen as a result of climate change, " said Dr Rowan Fealy from the Irish Climate Analysis and Research Unit (ICARUS).

"For example, the very hot, dry summer of 2006, followed by one of the wettest summers in history . . . that is just the sort of erratic, unpredictable weather we are expecting.

We also expect to see an increase in flooding, both on the coast and certainly inland too. The sea level is rising, and a large area of Dublin is susceptible to that. The flooding of February 2002 is currently seen as a one-in-100-year event, but we expect it will start happening every 12 years or so."

In a report published just last month by the Irish Academy of Engineers, it was suggested that events like the February 2002 floods will occur even more regularly . . . at least every five years, if not more often. The report said there was an immediate need "to adapt to the inevitable consequences of climate change" and that the "do-nothing" approach was no longer viable.

Radical measures Such is the reality of the threat now that another major report on the future of Dublin Bay, published last month, suggests that a massive coastal wall needs to be built around the Bay, from Howth to Dun Laoghaire, to protect Dublin from devastating floods.

The radical measures are proposed in a study commissioned by Dublin City Council and compiled by CDM consultants. The authors note that similar flood prevention approaches have been proffered in the past, but have been rejected because such largescale construction would be too environmentally damaging. However, the report suggests that we may no longer have the luxury of looking after the environment.

"Perhaps now the balance between human and environmental protection must change in some coastal urban areas, " said the study.

"The choice may be to protect such urban areas or to allow their gradual destruction in a series of catastrophic events."

According to Fealy, flooding is a problem well beyond the capital. Around the coast, Wexford city, Cork Harbour, Tralee Bay and the Shannon Basin also face very real problems. "The problem is that, historically, humans have settled on flood plains because that's where the best resources were, " he said. "Now, the sea is rising and basically any low-lying area is at risk from flooding."

Fealy said that while inland regions do not face a threat from sea surges, heavier rainfalls will almost certainly cause problems. "We are already seeing a change in how the rain is falling, " he said. "It's much more intense and for a shorter duration, which means the land has to deal with a large volume of water in a short period of time. What we will see is that the water will just hit the land and run off rather than being absorbed. That run-off will lead to flooding."

The experts agree that one of the major problems in protecting areas against flood destruction is anticipating and predicting where floods will occur. One of the easiest and perhaps most obvious defences against flood damage is to keep the numbers of people living in high-risk areas to a minimum. Scientist Dr John Sweeney from NUI Maynooth has urged a ban on further development near vulnerable coastlines and has called for a plan to "climate-proof" future development, especially of important infrastructure.

"The key thing here is adaptation, " he said.

"Irrespective of any controls that are imposed now, we are committed to global warming until 2050 and development plans need to reflect that. We need to look at where we are putting people and infrastructure, because if we don't take action now, then we could have problems in the future."

End of short-termism The Dart line on the southside of Dublin is one such example. Already this century, the railway line in Killiney has had to be moved twice as it has moved dangerously near the coastline. It is not unthinkable that it may have to be moved again in the next few decades. New houses, particularly in rural areas, are continually built on soft, sandy coastlines that are vulnerable to erosion.

"We have a real history of short-termism in this country, " said Sweeney. "The railway being moved twice was expensive and the taxpayer was caught out. We need to work now to prevent further such mistakes being made because of a lack of forward thinking."

Some city councils are beginning to react to the threat of climate change. In the Dublin Docklands area, where extensive building is underway, developers have had to comply with minimum basement level heights to ensure they are not as vulnerable in the event of a flood. Other developers have introduced sustainable drainage systems to cope with the additional rain to which we are being exposed.

But elsewhere, building continues apace in many high-flood-risk areas, even as insurance companies are backing away. "At this point, the insurance industry may be looking at areas of Dublin as being simply uninsurable, " said Fealy. "The increasing risk of flooding is just too high."

Lack of concern Despite all the warnings, the residents in high-risk flood areas don't seem overly concerned about the future. Tom and Moira Derwin, who run an off-licence on the Drumcondra Road in north Dublin, were hit hard by the floods in 2002, but believe that such a catastrophe is unlikely to happen again.

"At that time, it had rained for weeks and weeks and weeks before the flood, " said Tom Derwin. "It was just because of the rain that the flood happened. But I wouldn't be worried about it now. They've done a very good job on the banks of the river, so I think we'll be OK."

Derwin said he didn't know what to make of the assertion by experts that the heavy rains of 2002 were just an advent of the rains to come in the future. "I'm not worried, because there's so much building going on here, even in areas that are lower than us, " he said. "I think they know what they're doing. All we can do is hope. I really do think it was just a bit of heavy rain."

But heavier rainfall is exactly what is expected in the coming years and by the middle of this century, Ireland will be experiencing far heavier downpours, particularly in winter.

"Our temperature is set to rise by two to two-and-a-half degrees by 2050, and while we're not going to be a tropical paradise, we are going to see more flooding in winter, " said Sweeney. "We need to be prepared for that."

OVER the next 50 years, Ireland is set to see a temperature increase of between two and 2.5 degreesC and this will almost certainly happen by the end of the century. It may seem like a small change, but it will have a big impact on our water systems, including:

>> Increase of up to 1degreesC . . . negative impact on quality of our water.

>> Increase of up to 2degreesC . . . increased likelihood and magnitude of river flooding; reduced soil moisture; water shortages in summer in the east; fisheries may be affected as fish are sensitive to small changes in temperature.

>> Increase of over 2degreesC . . . sea level rise; loss of coastal habitats due to increased erosion; increased incidence of coastal flooding; more intense cyclonic and extreme precipitation events.

We might be in for a scorcher

No place is more than 100km from the coast. For Ireland, rising sea-levels pose a very real threat THE southern part of the country is sinking. The sea is eating away at the land. All around us, the water is rising. And no one knows exactly how high it's going to go. As the climate change expert Prof Richard Somerville points out, "no place in Ireland is more than 100km from the coast". For Ireland, rising sealevels pose a very real threat.

According to the Irish Climate Analysis and Research Unit (ICARUS), the east and south are considerably more at risk from coastal erosion than the North and West. "There's a very marked regional variation, " said Dr Rowan Fealy from ICARUS. "The Southern coast has a soft, sandy shoreline that is being eroded at a not insignificant rate. When you add that to rising sea levels and the fact that the south is actually subsiding, then you have quite a few factors working against you."

Fealy explains that 18,000 years ago there was a glacier on the North of Ireland that effectively compressed the rock, pushing it downwards. Since that glacier melted, the rock has been 'bouncing back up', slowly but consistently.

Now, in a see-saw type movement, as the north continues to rise, it is forcing the south downwards.

"You're only looking at a subsidence of about 0.5mm a year, " said Fealy.

"That sounds very little, but when you add it to the rise in sea level, over a long term, it's a problem."

Last year, the technology firm Mapflow created a computer simulation for the Sunday Tribune of what the Irish coastline could look like based on an 11-metre increase in sea-levels . . . the worst-case scenario that was spelled out by environmental guru Prof James Lovelock. The result was an unrecognisable map of Ireland. Cork city was gone, and much of Dublin had been submerged. Most of Drumcondra and all of Marino would be under water. Howth Head would actually be 'The Isle of Howth', as it would only be accessible by water.

The new coastline would mean that Ranelagh would be beach-front property and the N11 would be the new coast road.

However, according to ICARUS, even though 20% of the country is at risk from coastal erosion, the advance of the sea is unlikely to be quite so dramatic. "We're looking at losing about 380sq km of coastline by the end of the century, " said Fealy.

"I mean, already there have been quite significant rates of erosion over the last 100 years. A lot of it is down to man's activities, such as removing materials from the beaches for building. But the map of Ireland will not look significantly different."