Peo­ple in low-ly­ing ar­eas around Dublin Bay will have to get used to large struc­tures to safe­guard the city against the im­pact of cli­mate break­down

The Irish Times - Weekend Review - - NEWS REVIEW - Frank McDon­ald

and pos­si­bly as much as two me­tres be­tween now and the year 2100.

The IPCC, with thou­sands of sci­en­tists world­wide con­tribut­ing to its work, has based these es­ti­mates on the speed with which ice caps in the Arc­tic and Antarc­tic are melt­ing, as well as ris­ing ocean tem­per­a­tures and con­tin­u­ing green­house gas emis­sions.

Im­pacts will not be felt equally through­out the world, with some coastal zones ex­pe­ri­enc­ing a higher in­crease in sea lev­els than oth­ers, de­pend­ing on ter­rain, ocean cur­rents, lo­cal hy­dro­log­i­cal con­di­tions and other re­gional fac­tors.

But there can be no doubt that Dublin is on the dan­ger list. If the IPCC’s most pes­simistic pro­jec­tion for sea-level rise turns out to be ac­cu­rate, the im­pact would be cat­a­strophic for low-ly­ing ar­eas – with­out much stronger pro­tec­tion mea­sures.

Dublin Bay is “highly vul­ner­a­ble to ma­rine in­un­da­tion”, ac­cord­ing to a sum­mary of sci­en­tific re­search com­piled by the State-spon­sored Dis­cov­ery Pro­gramme.

“Vir­tu­ally the en­tire coast from Rush to Bray could be af­fected by sea-level rise. Re­claimed lands around the north Dublin es­tu­ar­ies of Roger­stown, Malahide and Bal­doyle, in­clud­ing lands des­ig­nated for hous­ing and recre­ational use, may be­come in­creas­ingly wa­ter­logged,” the re­port warned as long ago as 2000.

“The heav­ily de­vel­oped area around Dublin Bay is vul­ner­a­ble, es­pe­cially from east­erly winds and storm surges which may re­sult in struc­tural dam­age and flood­ing,” it said, adding that the city cen­tre it­self is lo­cated in the “ma­jor risk” zone.

It also found that boul­der-clay cliffs be­tween Killiney and Bray, and be­tween Bray and Grey­stones, are “highly vul­ner­a­ble”, while low-ly­ing land be­tween Grey­stones and Wick­low is li­able to flood and re­treat, threat­en­ing the Ross­lare rail­way line.

In a worst-case sce­nario, based on an ex­trap­o­la­tion of ge­o­log­i­cal data and the IPCC’s most pes­simistic pro­jec­tion, Howth could be­come an is­land (with Sut­ton wiped off the map) and Bal­doyle a penin­sula, while Bull Is­land could al­most en­tirely dis­ap­pear.

The Dart line be­tween Mer­rion Gates and Monkstown has al­ready been hit by pe­ri­odic flood­ing. A 2015 re­port for Iarn­ród Éire­ann con­cluded that its cur­rent min­i­mal coastal de­fences, which con­sist of only a wall in places, need up­grad­ing.

How this is to be done is still an open ques­tion. Ei­ther it will pro­ceed as a “stand­alone” project to pro­tect Dart com­muter rail ser­vices, or it could pig­gy­back on the Sut­ton-to-Sandy­cove cy­cle­way, which would in­volve build­ing a long em­bank­ment.

If the cap­i­tal is to be fu­ture-proofed, one of the ways to do it would in­volve con­struct­ing sub­stan­tial ma­rine “booms” in Dublin Bay to de­flect or at least mit­i­gate storm surges, as was pro­posed by a con­sul­tancy study sev­eral years ago.

But Dublin City Coun­cil, which com­mis­sioned the study, ef­fec­tively down­played this “vi­sion”, say­ing the con­sul­tants in­volved had as­sumed a sea-level rise of 1.5m to 3m, “which on cur­rent ev­i­dence should not oc­cur in the near fu­ture”.

The Ir­ish Acad­emy of En­gi­neer­ing, in its fu­tur­is­tic re­port Ire­land in 2050, pro­posed a large sea dyke in Dublin Bay – topped by a mo­tor­way to “com­plete” the M50 – to pre­vent ar­eas such as Clon­tarf and Sandy­mount dis­ap­pear­ing un­der a 500mm rise in sea lev­els.


What the coun­cil de­scribes as a “very pre­lim­i­nary study” was also done on putting a bar­rage – sim­i­lar to the Thames Bar­rier – be­tween the North Bull and Pool­beg light­houses, although the ¤1 bil­lion es­ti­mate meant it was “not cost ben­e­fi­cial but may be­come so in the fu­ture”.

Not that any such bar­rage would do much to save Clon­tarf, Sandy­mount or other low-ly­ing ar­eas around Dublin Bay; it would merely pro­tect the Dock­lands and the in­ner city. The Thames Bar­rier, on the other hand, safe­guards most of Lon­don.

De­signed to pro­tect the city against storm surges and ex­cep­tion­ally high tides, the Lon­don bar­rier is now ac­ti­vated six or seven times per year – twice as of­ten as it was in the 1980s – and it is ex­pected to be­come less and less use­ful over time.

The dev­as­tat­ing im­pact of storm surges was dra­mat­i­cally il­lus­trated when Hur­ri­cane Sandy hit New York City in Oc­to­ber 2012, killing more than 50 peo­ple and flood­ing parts of the sub­way net­work as well as road tun­nels into Man­hat­tan.

Since then, the city has de­vel­oped a com­pre­hen­sive “re­silience plan” that iden­ti­fies fu­ture flood zones and pro­poses a range of mea­sures to pro­tect them, in­clud­ing re­in­forc­ing beaches, build­ing bulk­heads and cre­at­ing rock break­wa­ters off­shore.

The costs of adap­ta­tion are es­ti­mated in bil­lions of dol­lars, which is why New York filed a law­suit seek­ing to re­cover dam­ages from five ma­jor oil com­pa­nies whose prod­ucts are blamed for caus­ing harm to the city; it was thrown out in July.

Bos­ton also has a cli­mate re­silience ini­tia­tive, Cli­mate Ready Bos­ton, which in­cludes a con­tin­u­ous re­view of the sci­en­tific ev­i­dence, and its plan­ning mea­sures such as “de­ploy­able flood walls” to pro­tect neigh­bour­hoods most at risk of flood­ing.

The US cities most vul­ner­a­ble to sea-level rise are mostly lo­cated in Florida, with Mi­ami in the front­line, even though its po­lit­i­cal lead­ers are in de­nial. Un­der the IPCC’s worst-case sce­nario, two mil­lion res­i­dents of Mi­ami could be dis­placed.

Rot­ter­dam, which is nearly all be­low sea level, was flooded in 1953, with the loss of 1,800 lives, and re­in­forced sea dykes were built to pro­tect it. These are now be­ing sup­ple­mented by “wa­ter plazas”, green walls and even float­ing neigh­bour­hoods.

In Dublin, the city coun­cil is col­lab­o­rat­ing with the Of­fice of Pub­lic Works (OPW) – the “na­tional com­pe­tent au­thor­ity” in this area – on the pro­vi­sion of flood de­fence walls such as the new gran­ite wall on Ge­orge’s Quay or the jagged one on City Quay.

The OPW stan­dard is a 1m in­crease in flood de­fences to pro­tect crit­i­cal in­fra­struc­ture, such as hospi­tals, fire sta­tions, old peo­ple’s homes, sewage treat­ment plants, power sta­tions, etc – based on the IPCC’s low-to-medium pro­jec­tions.

Af­ter se­vere flood­ing in Dublin in Fe­bru­ary 2002, caused by unusu­ally high tides mag­ni­fied by storm surges, the coun­cil put in place the Dublin Coastal Flood­ing Pro­tec­tion Project, which in­cludes de­vel­op­ing a coastal flood fore­cast­ing sys­tem.

“Cur­rently, sea walls are be­ing risen on a pri­or­ity or op­por­tunis­tic ba­sis to pro­tect as many build­ings – mainly res­i­den­tial – as pos­si­ble,” a coun­cil spokes­woman said. This “should cover us for at least 50 years of sea-level rise”, she added.

But build­ing up sea walls can be very chal­leng­ing, as shown by what hap­pened in Clon­tarf, where pres­sure from out­raged lo­cal res­i­dents seek­ing to pro­tect views of Dublin Bay ac­tu­ally led to a long stretch of the newly-built wall be­ing re­duced in height by 300mm.

There has been less con­tro­versy in Sandy­mount over rais­ing a sea wall by 360mm and in­stalling flood­gates along the prom­e­nade. A sec­ond phase of coastal pro­tec­tion works in the area will need to take ac­count of the bay’s des­ig­na­tion as an EU Spe­cial Area of Con­ser­va­tion.

Sooner or later, peo­ple liv­ing in low­ly­ing ar­eas around Dublin Bay will have to rec­on­cile them­selves to the cre­ation of much larger struc­tures – whether booms, break­wa­ters or sea dykes – if Ire­land’s cap­i­tal city is to be safe­guarded against the worst im­pacts of cli­mate break­down.

Ex­pert eval­u­a­tion

Each of the pro­pos­als in this “Cap­i­tal Ideas” se­ries has been put to a group of three ex­perts for an ini­tial “back of an en­ve­lope” eval­u­a­tion. They are: Frances Ruane, for­mer di­rec­tor of the Eco­nomic and So­cial Re­search In­sti­tute; Caro­line Spil­lane, di­rec­tor gen­eral of En­gi­neers Ire­land; and Cliff Tay­lor, Ir­ish Times eco­nom­ics colum­nist.

This idea re­quires ma­jor cap­i­tal in­vest­ment. Its scale is huge but that should not pre­vent the con­ver­sa­tion be­ing started im­me­di­ately. This must in­volve a wide range of dis­ci­plines. Ex­ter­nal as­sis­tance from the Nether­lands, which has 400 years plus of ex­pe­ri­ence, should be sought at the out­set. What will be im­por­tant is for this to be a whole of city cap­i­tal project, so that we get the best so­lu­tion for the city and not just for flood man­age­ment. This would be one of the coun­try’s big cap­i­tal projects over the com­ing decades, re­quir­ing ma­jor na­tional fund­ing and sup­port.

In En­gi­neers Ire­land’s State of Ire­land re­port this year, flood­ing re­ceived a C grade, mean­ing these sec­tors of in­fra­struc­ture are in­ad­e­quately main­tained and/or un­able to meet peak de­mand, and re­quire sig­nif­i­cant in­vest­ment.

Our or­gan­i­sa­tion calls for holis­tic flood risk man­age­ment for the pro­tec­tion of pub­lic health, crit­i­cal in­fra­struc­ture and the en­vi­ron­ment. This will re­quire ex­cel­lent and main­tained flood de­fences and warn­ing sys­tems and sus­tain­able land-use prac­tices.

Par­tic­u­lar at­ten­tion will need to be paid to mea­sur­ing and de­sign­ing for the ef­fects of cli­mate change and to the im­ple­men­ta­tion of re­cently-pub­lished flood risk man­age­ment plans.

The wider pub­lic must have a greater ap­pre­ci­a­tion for the level of in­vest­ment and struc­tures re­quired for flood risk man­age­ment.

Cli­mate chal­lenge is get­ting more se­ri­ous and we need a strate­gic ap­proach. There are high costs here. Frank McDon­ald refers to the ¤1 bil­lion es­ti­mate for a bar­rage in Dublin Bay, sim­i­lar to the Thames Bar­rier. The new Clon­tarf de­fences will cost an es­ti­mated ¤10 mil­lion.

Govern­ment has es­ti­mated that de­fences across the coun­try could cost ¤1 bil­lion. A UK study put the long-term cost of coastal de­fences at up to £30 bil­lion.

The key task is agree­ing what level of cli­mate change we need to play for and deal­ing with it on a planned ba­sis.

Like the cost of an age­ing pop­u­la­tion, this has to be baked into the na­tional fig­ures.


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