DUBLIN'S population could soar by nearly 300,000 over the next two decades, while Ireland's elderly population is set to double.
A new report from the Central Statistics Office (CSO) predicts a possible population spiral, which will pose massive challenges for health and transport services, city planners and the construction industry.
It finds that Dublin will be the big winner in the population stakes if past patterns of internal migration return in the period between 2016 and 2031. The capital's population is projected to increase by between 96,000 and 286,000, while the population of the greater Dublin area -- which includes the commuter counties of Kildare, Meath and Wicklow -- is set to rise by up to 401,000.
The Regional Population Projections report finds that as more young people move to the capital, the population share of the greater Dublin area could swell to over 42pc -- compared with 39pc in 2011 and just 32pc 50 years earlier.
This would mean the population of the capital would be growing by 20,000 a year through a combination of births and people migrating from other areas of the country.
Such huge population increases would put massive pressure on city services for everything from roads and colleges to hospitals, public transport and housing.
The entire Irish population is projected to increase by 613,000 in the period studied with all regions apart from the Dublin area set to lose residents to internal migration.
However, this would be more than offset by a natural increase of births exceeding deaths.
And there is set to be a huge surge in the country's elderly population, with the number of people aged 65 or more almost doubling in every region. The most marked increase would be in the mid-east region of Wicklow, Meath and Kildare, where there would be a 136pc hike in pensioners.
This is partly due to people living longer; nationwide, men are expected to live an average of four-and-a-half years more than in 2011, while women will live three-and-a-half years longer.
This will put further pressure on the country's creaking pensions systems, which have already seen many defined benefits schemes being wound up, while retirement age is being extended. It also poses huge challenges for health services, as many diseases are much more prevalent as people age.
The CSO gave a range of possible population changes based on traditional migration patterns and those seen in the period 2010-11, which were obviously strongly affected by the recession.
It said that births could fall from a high of 74,000 in 2011 to just over 55,000 in 2031 due to both falling fertility rates and there being fewer women of childbearing age.
"The report is not an attempt to predict the future, but rather presents how the population of the various regions will evolve under different scenarios by making assumptions about future trends in migration, both internal and external, and fertility," the CSO said.
New figures to be released next week will also show that death rates from circulatory diseases are down 35pc and cancer death rates have fallen by 11pc since 2003, according to Health Minister James Reilly.
Life expectancy in Ireland has also increased by a full four years since 2000 and is higher than the EU average.
The most recent Census figures show that Ireland has a population of 4.59 million people.