Thousand of homes and businesses are at risk of being inundated with flood waters due to rising sea levels caused by climate change.
As much as 20pc of the coastline is at risk of erosion as sea levels rise because of warming temperatures. And, unless there are cuts in greenhouse gas emissions, the changes may be irreversible.
Leading climate expert Prof John Sweeney has warned that if climate change remains unchecked, it will result in warmer and hotter summers, warmer and wetter winters and the risk of more frequent flooding.
His comments come in advance of UN talks in Paris next month, when it is hoped to strike a global deal to reduce emissions and limit climate change.
"Ireland has 4,577km of coast, and more than half the population lives within 15km of the sea," he said.
"Around 20pc of the coast is at risk of erosion, with sea-level rise already having a significant impact on the soft boulder clay coasts of the east.
"Counties Dublin, Down, Louth, Wexford and Wicklow are particularly at risk, but the west and south are also affected, with low-lying bays and estuaries such as Cork Harbour, Clew Bay and especially the Shannon Estuary displaying increased exposure to sea-level rise."
Computer modelling produced for the Environmental Protection Agency suggests that other areas likely to be affected include Tralee Bay and Castlemaine Harbour.
It previously warned that the counties most at risk of increased flooding are Cork, Dublin, Galway, Mayo and Waterford. The threat of coastal erosion is high in Cork, Galway, Kerry and Mayo, with sea-level rises likely to most affect Clare, Galway, Kerry and Sligo.
The warning comes after the World Meteorological Organisation this week warned that the level of greenhouse gases in the atmosphere had reached record highs and the planet was moving into "uncharted territory at a frightening speed".
The UK Met Office also reported that average global temperatures had increased by 1C this year. Scientists believed that if average temperatures increase by 2C or more, the changes will be irreversible.
Prof Sweeney said: "It is clear that the window of opportunity is closing rapidly, and unless radical emission cuts in greenhouse gas emissions are achieved within the next decade or two, a tipping point may be reached."