Cyclone Gabrielle: Simon Wilson on wild weather and wobbly ideas

OPINION:

“There is no point talking about 1-in-100-year events anymore,” Finance Minister Grant Robertson told the Auckland Business Chamber last week. “We will be dealing with them regularly.”

True that. One of the many brutal lessons of Cyclone Gabrielle and the Auckland Anniversary Weekend storm is that if extreme weather can happen this year, it can happen again next year.

Another lesson: If the storm was unprecedented this time, that can also happen again.

The rains that fell on Auckland over January 27-28 were 60 per cent greater than those expected in a “1-in-100-year” rainstorm. No one thought it could be that bad, and yet it was. It was the same for the people of Hawkes Bay and Tairāwhiti. And we will surely experience this awful record-breaking again.

Some meteorologists prefer the term “1 per cent chance”, which means the same as “1 in 100″, but carries the message that, however small, there is a real chance it can happen.

But that’s not good enough, partly because it’s obviously out of date and partly because it still carries the message that we shouldn’t worry too much.

The whole debate about climate change has been compromised by numbers like this. We look ahead, to what the world might be like in 2050, and to if, or when, the temperature warms by 2 degrees above pre-industrial times, or 3 degrees, or more.

The message is that a climate crisis awaits us in the future. That we have 30 years before we have to change our ways.

Maybe we should forget about those numbers, too. The climate crisis has engulfed us now.

Greens co-leader and Climate Change Minister James Shaw said last week: “I don’t think I’ve ever felt as sad or as angry about the lost decades that we spent bickering and arguing about whether climate change was real or not, whether it was caused by humans or not, whether it was bad or not, whether we should do something about it or not, because it is clearly here now, and if we do not act, it will get worse.”

Green co-leader James Shaw.

He’s right, but despite the new-found consensus that Something Has To Be Done Now, the ferocity of these storms has revealed that we do not know enough about where and how we can live safely.

Sadly, misleading numbers aren’t the only wobbly ideas getting in the way. Here are three more of them.

Wobbly idea 1: ‘Don’t build on a flood plain!’

Hang on. Almost every city in the world is built on a river or a coastline, or both, and therefore is on or near flood plains. The history of cities is a history of how to manage the risks posed by water.

There are lots of ways to do it. In the Netherlands, most people live below sea level, protected by dykes. In many cities in Asia, there are houses on stilts above the water. In Auckland itself, the suburb of Sandringham used to be a swamp – what we now call a wetland – before it was drained and turned into a suburb.

Managing stormwater in Auckland is the job of Healthy Waters, a division of the council. Its boss Craig McIlroy told me yesterday the city has 100,000 homes “on a flood plain”. Most of them have been there a long time and some of them flood quite frequently. But in the newer developments, the news tends to be much better.

In Mt Roskill, where Kainga Ora and others are building 10,000 new homes, the drains have been upgraded and, more importantly, “overland flow paths” and flood catchments have been established.

On the night of January 27-28, water ran down the streets and the suburb’s Freeland Reserve flooded, and over the next three days the water seeped away into the ground. The houses stayed dry. The same thing happened with new developments in Drury, Northcote and elsewhere.

There are some flood-prone areas we probably shouldn’t build on and some sections of coastline we should retreat from too. But choosing the best solutions for each area is complex and, these days, it doesn’t always rely on expensive pipes underground.

In a new subdivision in a big rain event, says Healthy Waters’ head of planning Nicholas Vigar, they plan for perhaps 40-50 per cent of the water to go down the drains, while 50-60 per cent will spill along an overland flow path. Down the street, on to the local park.

It’s cheaper to build, easier to maintain and, perhaps most valuably, it doesn’t have the same capacity constraint.

Wobbly idea 2: ‘Density means more disaster!’

Infilling suburbs with houses puts too much demand on all the water infrastructure, it’s said, so the drains are overwhelmed more quickly. And it creates more hard surfaces for water to run off, which also overwhelms the drains.

It’s obviously true: If density is done badly, those things happen.

But there’s nothing about density that means it has to be done like that. New Lynn is a flood-prone suburb and is rapidly becoming a far denser part of the city. It’s not immune to flooding, but bigger and better stormwater culverts and pipes have been built, along with more flow paths, and there’s more of all that to come.

McIlroy says New Lynn’s new culverts did their job well over Anniversary Weekend.

In 2020, New Lynn suffered a massive flood, but much work is now being done to avoid this continuing to happen. Photo / Dean Purcell

Not all the news is so reassuring. The new building rules that will modify the Auckland Unitary Plan could mean we don’t have enough green spaces in urban areas. And while the city has planted millions of new trees in the last few years, it has also seen the widespread destruction of many mature trees, on public and private land.

These things clearly need a rethink.

The reality is that for cities in a climate-crisis world, density and greenery need each other, and not just to mitigate against floods.

The simplest way to build flood resilience into Auckland would be to put up many more apartment blocks, say 6-10 storeys, especially in places that don’t readily flood. At the same time, we would preserve our parks, and build more, and we would convert as much public land as possible to greenery: trees, grass, vegetable and flower gardens, play areas, the works.

What public land could we do this with? About half the area of all the wide streets that used to be tram routes.

The best place to create an exemplar for all this is Great North Rd, all the way from Ponsonby Rd to Pt Chevalier. Or Avondale. Or beyond.

The Feynman, one of many residential developments now under construction or already built on Great North Rd. These buildings need a greened-up streetscape to accompany them. Photo / Ockham Residential

Many suburban side streets are also wider than is necessary for driving and parking on: they could triple their berms and residents could be encouraged to plant them.

I know, it’s almost preposterous. Especially as there’s an added bonus: public transport, walking and cycling would become more attractive and driving everywhere would seem less so.

In climate-action terms, this is called adaptation and mitigation: The city would become more flood resilient and we would reduce our emissions. And both would be achieved through the same development strategy.

What it requires is an understanding that we should stop treating housing and transport as separate planning fields. They are two parts of the same thing: land use.

Wobbly idea 3: ‘Forget about emissions’

Despite the value of integrated land-use planning, there are those who say it’s time to forget about emissions and focus just on the adaptation side. This is the new version of climate denialism and we’ve heard hints of it from Christopher Luxon and Wayne Brown, among others.

We need to do both. New Zealand’s emissions, per capita, are among the highest in the world. We have no right to pretend we’re exempt from responsibility.

Besides, what would happen if we did allow the cause of the crisis to continue unchecked, consoling ourselves we could “adapt” our way to safety? We’d build seawalls and bubbles over cities, then sit back and wait for our well-planned “flood paths” to turn into uncontrollable raging rivers.