Drought will become a major problem in Northern Ireland because of changing weather patterns, a leading scientist has warned.
Ulster could face the prospect of wetter winters with increased flooding, and drier summers with acute water shortages, if current climactic trends continue.
Climate change expert Dr John Sweeney believes the Water Service must start to plan for the possibility of water shortages by building more reservoirs to trap winter rainfall.
Dr Sweeney, who will today address a climate change conference in Ballymena, said serious summer droughts could be the norm in Ulster in 30 years.
"Considerable investment will be required if Northern Ireland is to avoid serious shortfalls in its water supply," the Maynooth academic said.
"Most research, including my own, suggests a reduction in summer rainfall, particularly in the eastern half of Northern Ireland, possibly a reduction of between 20-40%.
"This will be offset with increased rainfall during winter, especially in the western part of Northern Ireland - we project a rise of about 10%.
"The seasons will be more marked and the droughts will result in reduced river levels and less soil moisture.
"The changes are a consequence of global climate change, which is driven by human factors. The Republic of Ireland is re-doing its flood calculations and the authorities in Northern Ireland also need to think about the future."
Ulster social partnership Concordia organised the conference. Its chairman, Seamus McAleavey, said the conference would help senior policy-makers to tackle climate change.
He said: "Climate change isn't going to go away - it's here, it's getting more serious, and Northern Ireland will lose out both economically and socially if we don't decide now what we're going to do to tackle it."
The conference at Ballymena's ECOS Centre will be addressed via video link by environmentalist George Monbiot.