June 4, 2023

Muriwai deaths are a wake-up call for climate change, experts say

Watch: Footage shows the extent of the damage in Muriwai from Cyclone Gabrielle.

Professors and climate change experts say the devastating Muriwai disaster highlights what needs to be done to ensure something similar doesn’t reoccur.

Cyclone Gabrielle has caused significant damage after tearing across the North Island, bringing landslides to Muriwai.

Two firefighters were killed after investigating flooding in a house on Motutara Rd in Muriwai and the house was crushed from above by a landslide.

Dr Judy Lawrence from the Climate Change Research Institute said the disaster was a “tragedy” and that the power of water and sodden land is well-known at Muriwai.

And she warned another disaster is certain to happen before 2050.

“I predict tragedy for locations known to be risky areas, such as low-lying coastal locations at risk from sea-level rise,” said Dr Lawrence.

Dr Lawrence said it’s not just the heavy rainfall that is the issue – “what makes it worse is the ground material and the landforms combined with where houses are located,” she said.

She said fixing the legislation now to strengthen what councils are empowered to do will help to avoid hazardous places.

“It will make climate change risk a primary factor in planning, consenting and housing people,” she said.

She said the consequences of building in hazardous locations are too high.

“We cannot afford to have more houses located in dumb places,” she stressed.

Meanwhile, University of Auckland geology Professor Martin Brook described it as a “moral hazard”.

“For example, providing public compensation to private property owners affected by a landslide or a managed retreat programme, may increase incentives to build or develop further in high-hazard zones,” he said.

When Newshub asked what Prof Brook thought of the Muriwai disaster on Monday he described it as “tragic”.

“Particularly given the rainfall-triggered landslide deaths there in 1965,” he said.

However, Muriwai’s latest deaths raise questions about why homes are being built in areas with a history of deadly slips.

Prof Brook said there are two main reasons people continue to live in hazardous areas – people who think “it will never happen to me”, and others who “may not have full knowledge of site issues”.

He said to prevent more houses being built on damaged land, we need to rationally reflect on what has happened and apply a range of passive and active controls, for example:

Passive controls

  • Using area-wide landslide mapping based on high-quality digital elevation models, and once a produced map has been formed, utilizing it to inform future planning
  • Once hazardous slopes have been identified use slope monitoring approaches such as a satellite radar to monitor slope movement
  • Apply adequate setback distances above and below slopes, to remove houses from high-risk areas

Active controls

  • Understand what type of landslides are likely to occur and in what materials (solid and/or rock)
  • Removing weak material from slopes above houses
  • Catch fences or deflection walls to channelise landslide debris away from houses

Meanwhile, Professor of physical geology at Wellington University James Renwick described the recent Muriwai disaster as a new climate change wake-up call.

He said the storm this week is bound to have been made more damaging because of climate change.

“Large parts of the North Island have seen flooding and damage that is outside most people’s experience. Combined with the unprecedented flooding in Auckland last month, I think the whole country has had a clear ‘wake-up call’ about climate change,” Prof Renwick said.

He said that extreme events, especially extreme high rainfall and coastal inundation, will only become more intense in future as the climate continues to warm.

“If people build back on sites that were damaged this week, they expose themselves to increasing risk,” he warned.

“There needs to be a broad conversation across the country about what levels of exposure to hazards are acceptable in different regions, and who is prepared to pay when disaster strikes.”

He said there is only one way to rein in climate change and that is to “stop burning fossil fuels and stop emitting greenhouse gases, especially carbon dioxide”.

Prof Renwick said it is humanity that is driving the problem, and it is we who have the power to choose when to stop it.

“We know that once emissions of greenhouse gases go to zero, global warming will stop within a year or two. We are always in control, we just need to find ways to move away from fossil fuels – as fast as possible,” he said.

Prof Renwick said to protect ourselves, people need to adapt to climate changes that have already happened.

“The effects of flooding, of coastal erosion, of droughts and heatwaves, but crucially, we also need to mitigate – to reduce emissions of greenhouse gases to zero,” he said.

“We need to do this, as rapidly as possible, before the effects of climate change become unmanageable.”

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