Tune into information from about any a part of the planet, and there’ll probably be a headline about excessive climate. While these tales might be particular to the placement, all of them have a tendency to incorporate the amplifying results of local weather change.
This consists of the wildfire devastation on the island of Maui in Hawaii, the place rising temperatures have dried vegetation and made the chance that a lot higher. In Italy, summer season temperatures hit an all-time excessive one week, adopted by huge hail storms and flooding the following.
Flooding in Slovenia not too long ago left three individuals lifeless and induced an estimated €500 million in injury. At the identical time, rainfall in Beijing has exceeded a 140-year file, inflicting wide-scale flooding and leaving 21 lifeless.
These northern hemisphere summer season occasions mirror what occurred final summer season in Auckland, categorised as a one-in-200-year occasion, and elsewhere within the North Island. So far this yr, rainfall at Auckland Airport has surpassed all information courting again to 1964.
Given extra rainfall is among the likeliest signs of a altering local weather, the brand new report from the Helen Clark Foundation and WSP – Sponge Cities: Can they assist us survive extra intense rainfall? – is a well timed (and sobering) reminder of the urgency of the problem.
NIWA, CC BY-NC-ND
The “sponge metropolis” idea is gaining traction as a technique to mitigate excessive climate, save lives and even make cities extra nice locations to reside.
This is especially essential when present city stormwater infrastructure is commonly already ageing and insufficient. Auckland has even been chopping spending on essential stormwater repairs for no less than the previous two years.
Auckland floods: even stormwater reform received’t be sufficient – we want a ‘sponge metropolis’ to keep away from future disasters
Politically no less than, this isn’t shocking. Stormwater infrastructure, as it’s at present constructed and deliberate, is dear to develop and preserve. As the Helen Clark Foundation report makes clear, New Zealand’s pipes merely “weren’t designed for the large volumes they should handle with rising seas and rising excessive rainfall occasions”.
The nation’s present mixed stormwater infrastructure entails a 17,000 kilometre pipe community – sufficient to span the size of the nation ten occasions. The value of upgrading the complete water system, which encompasses stormwater, might attain NZ$180 billion.
This contrasts starkly with the $1.5 billion councils now spend yearly on water pipes. The report makes clear that implementing sponge metropolis rules received’t wholly remedy flooding, however it could considerably scale back flood dangers.
Trees and inexperienced areas
The actual bonus, although, lies within the potential for sponge metropolis design to cut back dependence on costly and high-maintenance infrastructure.
There are already examples in Auckland’s Hobsonville Point and Northcote. Both communities have included inexperienced infrastructure, resembling floodable parks and planted wetlands, which stored close by properties from flooding.
But the report’s suggestions are at odds with among the present political rhetoric round land use coverage – specifically “greenfields” growth that encourages city sprawl.
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The report urges that cities be constructed upwards reasonably than outwards, and pushes again on residential infill growth inspired by the Medium Density Residential Standards.
Citing a latest report on inexperienced house from the Parliamentary Commissioner for the Environment, the Helen Clark Foundation report argues for the preservation of city inexperienced areas – like backyards – as a part of the flood mitigation method.
Preserving tree cowl is one other pressing precedence. Trees assist take up rainfall, scale back erosion and supply important shade and cooling in city areas – counteracting the harmful city “warmth island” impact. Citing knowledge from Global Forest Watch, the report states:
Auckland has misplaced as a lot as 19% of its tree cowl prior to now 20 years, Dunedin a staggering 24%, Greater Wellington round 11% and Christchurch 13%.
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Incentives for householders
Making Aotearoa New Zealand extra resilient to excessive climate, the report says, needn’t break the financial institution.
It recommends elevating the nationwide minimal requirements governing the share of the full space of latest developments that should be left unsealed. This would make sure the implementation of sponge metropolis ideas, and see buildings clustered to maximise preserved inexperienced house.
The authorities also needs to require native councils to plan for and supply public inexperienced areas, and to develop long-term sponge metropolis plans – simply as they do for different forms of essential infrastructure.
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Neighbourhoods might be retrofitted to incorporate inexperienced roofs, permeable pavements and unsealed automobile parks. Land use and zoning might additionally encourage extra vertical growth, reasonably than sprawl or infill housing.
The authorities might additionally present incentives and training for householders to encourage minimising sealed surfaces, unblocking stormwater stream paths, and changing lawns with native crops and rain gardens.
More excessive climate and intense rainfall is a matter of when, not if. As the Helen Clark Foundation report makes clear, spending future billions is much less of a precedence than performing urgently now.
Timothy Welch doesn’t work for, seek the advice of, personal shares in or obtain funding from any firm or organisation that will profit from this text, and has disclosed no related affiliations past their educational appointment.