Sea level rise over the last 150 years
However a recent climate change conference in Copenhagen, covered in the New Scientist , warns that the currently observed rise of 3mm per year is far above what was predicted in the TAR:
"Because modelling how the Greenland and Antarctic ice sheets will react to rising temperatures is fiendishly complicated, the IPCC did not include either in its estimate. It's no small omission: the Greenland ice cap, the smaller and so far less stable of the two, holds enough water that if it all melted, it would raise sea levels by 6 metres on average across the globe."
According to John Church of the Centre for Australian Weather and Climate Research, "By 2100, sea levels could be 1 metre or more above current levels".
Presumably responding to this, FG Cllr Eamonn O'Boyle warned in last weeks Argus that "a rise of one metre or more in global sea levels would be quite disastrous in itself, as all low-lying areas such as most of Dundalk, would be threatened by catastrophic flooding if this recent authoritative prediction materialises."
Cllr O'Boyle's solution is to enable a local developer to raise the dykes between Soldiers Point and Blackrock by 2 metres; in exchange the developer would be granted permission to develop the floodplain for housing and other uses.
The Independent newspaper notes that "Britain's Environment Agency was apparently unique when it discarded the IPCC's 2007 advice as flawed. Based on its own estimates, it is planning flood defences for 2100 on the basis of a one-metre rise in sea levels – with a "worst-case scenario" of 2.7 metres."
Countering Cllr O'Boyle's comments, Paraic McKevitt, a County Council candidate for the Green Party, was quoted in the same newspaper, "'Climate change and rising sea levels are very critical issues facing low lying coastal communities around Dundalk Bay. What we need is a Dundalk Bay flood protection plan and not a one-off embankment that leaves one development dry while increasing the flooding risk for everyone else," referring to the phenomenum whereby strengthening sea defences in one area can have knock-on effects on other areas.
According to the Office of Public Works the cause of past flooding events in the area has been due to rainfall swelling the rivers Ramparts, Blackwater, and Fane, as well as, or combined with, high tides and storm surges.
Extract from OPW report
The advice given by the OPW in regard to development on floodplains, on their special web site is unequivocal:
"Impact of flood risk on development Locating development in an area at risk from flooding can lead to property damage, human stress and hardship, problems obtaining property insurance and consequential demands for the expenditure of local authority or central government resources on flood protection works. The construction of protection works either at the time of the development, or at a later date, will incur additional costs, may not provide absolute immunity from the risk of flooding and can, if not appropriately designed, have detrimental effects on flood risk elsewhere. "
It continues:
"Impact of development on flood risk upstream In times of flood, the river flows not only through its normal channel but also along the flood plains. Any constriction of the natural flow path can 'back-up' the river and lead to increased flood levels upstream. The construction of buildings or houses, and particularly embankments for infrastructure or protection, in or across a floodplain can therefore not only put the development itself at risk of flooding, but can also increase the flood risk for land and properties upstream. The same is obviously true of any construction in, or encroachment into, the normal river channel. "
And finally,
"Impact of development of flood risk downstream Natural or agricultural land, such as forests, woodland, pastures or crop fields, is normally able to absorb a considerable proportion of any rain that falls onto it. Covering such land with buildings, tarmac (such as for parking areas or roads), or other impermeable materials significantly reduces this ability to absorb rainfall, and will lead to increased land runoff. As a result, large developments, including those away from major rivers, can increase river flows and the risk of flooding to land and property downstream. A number of smaller developments built up over a period of time can have the same effect.
Impact of tidal flood risk on development A combination of high tides, waves, high winds and surges developed from low-pressure systems can lead to extensive flooding. Current predictions of climate change indicate that the risk of flooding from the sea will increase in the future. Any area below current or predicted future peak sea levels, including areas behind existing defences that offer only a certain level of protection, are at risk from flooding in the future."
The debate on how Dundalk, and indeed County Louth, should respond to rising sea levels is joined - we look forward to following how it develops!
