The long, blue lineMay 8, 2019 | 0 | Education and Training
OPINION: Recently, the climate action group, ‘Extinction Rebellion’, held a demonstration (in the truest sense of the word) of where the sea will lap the streets of Nelson with a one metre rise in its level.
One hundred supporters held up a long blue banner to mark the line, along Trafalgar and Bridge streets.
Sea level rise is perhaps the most palpable and comprehensible of climate change impacts. We can see on maps or in our imaginations where the sea might reach in 2050 and in 2100, if we don’t drastically cut our emissions.
Even if we do cut, sea level rise is occurring now and will continue, but we might avoid the worse scenarios.
Nelson has a 70km coastline and Tasman a 700km one. From north to south, particularly vulnerable areas are Pakawau in Golden Bay, Abel Tasman beaches, Motueka’s shoreline houses, Mapua, Ruby Bay and Nelson’s central business district.
Behind these stark facts, there is a large amount of scientific study. Some of this is summarised by journalist, Neville Peat, in a book called The Invading Sea (The Cuba Press, Wellington, 2018).
He lists the possible responses in rank order of desirability as avoid (by cutting greenhouse gas emissions), accommodate (eg by not building on potentially inundated land), defend (eg by building a boulder wall), retreat. It is accepted by those involved in the issue that for some areas retreat will be necessary. That is, people will have to leave their houses and relocate.
This leads us to the difficult issues of the insurability of houses at risk of erosion or flood effects, and of who will pay for managed retreat. There is much discussion on these issues.
On the topic of defending land from sea incursion, experts point out the futility of long term defence (‘You can’t hold back the sea’).
In the shorter term, natural or ‘soft’ defences are preferred, such as building up and stabilising sand dunes with planting. Rip rap walls – large boulders, sometimes stabilised with special fabric, at a 30 degree angle to horizontal – are a ‘harder’ response.
New Zealand expert on the management of coastal hazards, Dr Judy Lawrence , chairs a Climate Change Adaptation Technical Working Group set up by the central government.
This group strongly recommends national coordination of adaptation to the many impacts of climate change, including coastal hazards. Also recommended to local councils is a process of consultation with communities called Dynamic Adaptive Pathways Planning (DAPP).
Our two councils, Nelson City and Tasman District, are highly aware of the need to engage in adaptive planning and implementation.
Designated staff members focus on developing responses. Community consultation is planned. Action by the councils will be at all levels including avoidance of the worst scenarios by action on cutting carbon emissions, accommodation by not permitting development on hazard-prone land, defending certain areas with rip rap walls. The latter is an expensive option.
This is an issue that involves all of us, not just those who live next to the sea.
The thought of losing our beloved beaches in the Abel Tasman is enough to bring tears to the eyes. We’ll need to engage more closely with our councils as we face this, and decide together on thoughtful community responses.
* Joanna Santa Barbara lives in Motueka and is a member of Zero Carbon Nelson Tasman.