Interest peaked at the 80th annual Thomas Cawthron Memorial Lecture when attendees discovered Nelson’s coastal land had retreated up to 250m in just half a century.
The lecture, which was held on Tuesday, 27 June, attracted a “diverse” crowd of about 300 people, with scientists Professor Tim Naish and Professor Richard Levy discussing the climate causes of sea-level rise, and how to resolve the issue.
The lecture also included presentations by Dr Anna Berthelsen and Jacqui Stuart from Cawthron Institute, who shared the organisation’s work in Antarctica to understand and find solutions to climate change.
Richard says he and Tim presented data gathered by a tool which observes earth from space to demonstrate how the earth’s system, atmosphere, ocean, and ice sheets were changing.
The data showed there had been ongoing land subsidence on the Nelson coast in the past 50 years.
“We were able to show some data around the Nelson region where actually parts of the coast had been retreating up to 250m over the past 50 years,” Richard says.
“The area around the airport has been retreating anywhere between zero and 50m over the past 50 years, so it’s not moving out into the sea, it’s actually eroding slightly,” he says.
Tim says the use of the tool is “very powerful” for planners, decision makers, and local authorities in times when coastal communities were vulnerable to land subsidence and sea-level rise.
“But with more information comes more complexity… once you see the world is more complicated than we thought… it’s more uniformed and that’s important because one size does not fit all when it comes to this.
“If you’re a developer and you want to spend $100 million building something on the coast and the council’s just going to go, ‘oh, we quite like that because it’s good for the local economy’, it’s dangerous to just do a risk assessment around that one thing.
“Because the whole region is changing and changing differently.”
Tim adds that while the data made things “more complicated” for coastal communities, it would enable them to understand the full picture and make future plans.
“It’s quite a shock to people to suddenly have to be confronted with all of this, but the more you take on the information and discuss it, then I think the more empowered you’re going to feel about your future,” he says.
“If you already are in a [coastal] house and the family has been there for generations… then there are adaptation options.
“The easier ones are we could lift the floor up a bit, we can let a wetland regenerate so it buffers, we could have mangroves growing… and then if you’re really keen to stay put and you can’t move, then you need to consider harder engineering options.”
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Tim says, while land subsidence was caused by geological processes, the biggest way individuals could reduce sea level rise was reduce fossil fuel use by way of transport.
Both Tim and Richard say they were encouraged at the level of engagement during the lecture, particularly by the younger generation who were active through the Q&A session.
Previous speakers at the lecture have included the likes of Sir Edmund Hilary and Sir Ernest Rutherford.
