Mapping climate change impacts for adaptation success

The team that worked on this project can tell you where sea level rise is going to most keenly impact New Zealand’s coastal infrastructure, and what the “tipping” point is, that signals significant loss. They understand concepts like “episodic inundation” and have been researching the impact of extreme sea level flooding events, as well as the more gradual effects of sea level rise over time, to understand what it means for our roads, our power supplies, our wastewater plants and our drinking water supplies.

In short: the news isn’t all that rosy.

But, what’s important is not that they understand it themselves, but that they’ve made a habit of sharing the information developed in Infrastructure disruption from coastal flooding so that decision-makers can make use of it.

What those decision-makers need to plan for represents a major shift for local councils, central government offiicals and for private asset owners: adaptation to climate change.

Their work in the Deep South Challenge has considered the impact of extreme weather and sea level rise in focused case studies, but also from a national perspective, producing a mapping tool that allows users to show how sea level rise might affect them and their communities under different scenarios.

These maps take into account projected sea level rise, as well as the movement of land (i.e. where land is subsiding, sea level rise is expected to have more of an impact) to give an overall picture of where our vulnerabilities are.

It’s no secret that in many places around Aotearoa New Zealand, the sea is encroaching on our built environment – often reported in terms of the mess it makes of coastal property frontage. But the scale and shape of this disruption into the future is now a lot more visible thanks to projects like this one.

Cascading failures

As scary as it is to think about the damage a massive inundation of salt water might have on, say, our water system, what the research team have been focused on is what that means for “multi-hazard resilience planning”. That is to say, conceptualising asset disruption as a result of rising sea levels is a pretty easy task – most people get that if a bridge is washed out during a storm, people might not be able to get home. In the latter years of the Challenge, we saw this happen with Cyclones Gabrielle and Hale. But what’s less easy to understand is the flow on effect of something like sea level rise on the greater roading network – and the sectors that rely on it.

A big focus of this project was mapping the impact on New Zealand’s roads. Our fuel network, for example, relies on the efficient operation of those roads for distribution. The team found in a “spatiotemporal” (i.e. where and over what time period) analysis of the risk of national road networks to episodic coastal flooding and sea level rise that road networks are on the “front line” for climate change. And, that “New Zealand’s direct economic risk was primarily driven by direct damage to local access, collector, and arterial roads.”

This finding essentially tells those with control over the maintenance of our roads (territorial authorities, and for highways, central government) that once this transport system is compromised, the impact on other aspects of our society and economy happen thick and fast. The data also shows this compromise could emerge earlier than otherwise predicted.

Understanding timelines and tipping points

One of the key issues with communicating about climate change and our immediate need to adapt – a central tenet of the Deep South Challenge – is that it can be difficult to reckon with impacts that may be decades away (however sure we are about their eventual arrival).

However, it’s not necessarily the immediacy of the event itself that requires our focus – it’s the length of time it takes to grapple with the administrative and real costs of making massive calls about how to deal with something that will cost billions. You can’t move a pump station or major highway overnight.

In a case study focusing on South Dunedin, this project assessed infrastructure vulnerability to the sea level rise events expected over the next century. A hundred years is a long time, but as we all know, those “1-in-100 year” events seem to be happening a lot more frequently than that.

Through this work, the research team were able to isolate an extreme sea level tipping point of 0.6m, “where direct loss of road access and electricity services is extensive, and causes indirect loss of telecommunication services. This also impacted the functionality of a key wastewater pumpstation servicing the wider region.”

Roads first, then electricity, then communications, then wastewater. With this understanding of a likely chain of events in these scenarios, decision-makers are empowered to do the required planning, and calculate the likely, significant, costs.

Read and access more resources from this project here.