Simon Upton Photo: [https://www.flickr.com/photos/eu2017ee/35725837402flickr]
Two of Aotearoa's largest centres have lost up to a third of their green space in recent decades.
That's the finding from a report by Environment Commissioner Simon Upton, looking at changes in Auckland, Hamilton and the Wellington region over since 1980.
Upton said green space per-person fell by at least 30 percent in Auckland, and more than 20 percent in Hamilton.
Nearly all of this loss is from private residential land.
More backyards and sections were being turned into housing, and new builds tend to put larger houses on smaller sections.
Upton said new government rules promoting housing intensification would likely add to the pressure.
He said solutions included building more high-rise apartments, and repurposing neglected road reserves and public land.
Carparks and existing green space should also be planted with trees to provide more shade.
Meanwhile, Wellington is bucking the trend, with the amount of green space staying the same as the city has grown.
Almost two thirds of the urban area is green space, and that figure increases if the outer green belt is included.
'Green spaces should not be optional'
As we densify our cities to accommodate population growth, we must not lose sight of the environmental benefits that urban green space provides, Parliamentary Commissioner for the Environment Simon Upton warns.
Green spaces in Auckland are at a premium. Photo: 123rf.com
"Temperature regulation, stormwater management, air filtration and habitat provision - don't just benefit individuals.
"They benefit everyone around them. They are a form of infrastructure every bit as important as pipes and roads.
"The ability of our trees and parks to filter stormwater flows and cool their immediate surroundings can mitigate some of the heat and excess water that impervious surfaces generate.
Upton said green spaces should not be optional, yet many councils were struggling to improve the quality and availability of public green spaces to compensate for the loss of private yards and gardens.
Intensification good, but must be managed
Upton said there were real benefits to ongoing urban intensification.
"Not only does it help to address New Zealand's housing supply shortage, it does so without the increase in transport emissions that would likely accompany growth outwards.
"But not all intensification is the same, and the style of infill townhouse development that is currently happening within our cities comes with particular risks for the existing network of urban green space."
New rules for intensification require a minimum of 20 percent of a development site be retained as landscaped area.
And they identify accessibility to natural spaces and open spaces as a key element of "well-functioning urban environments".
But Upton writes territorial authorities are not required to plan for or provide public green space in the same way they are required to for roads or three waters infrastructure.
"Throughout this investigation, council staff, green space professionals and even developers have expressed frustration with this 'optionality' that, in effect, means that green space is accorded a lower priority than other forms of infrastructure."
"Changes should be made to both the Local Government Act and the National Policy Statement on Urban Development to give equal priority to green spaces and network infrastructure," the report said.
Intensification and climate change will mean that a typical Auckland suburb will be hotter and more prone to flooding in future.
More high rises, plant out neglected public land
He said one solution was to build more high-rise apartments, and improve public green spaces to counteract the loss from private dwellings.
That could include improving canopy cover in local parks, road reserves and other neglected corners of public land by planting trees, or repurposing impervious grey spaces such as carparks with some form of vegetation.
Because it is difficult to retrofit green space, it is crucial it is adequately provided for from the outset for new subdivisions.
Councils should be more proactive about buying land to be turned into parks.
"The changes we are making to the shape and form of our cities are largely irreversible.
"We must make sure the underlying environmental services that green spaces provide are taken into consideration.
"Once they are gone, they are difficult to get back," Upton said.
How our cities are growing and change
The rate of population growth in New Zealand cities increases.
Auckland's population grew by almost 30,000 people a year between 2016 and 2020.
The combined population of Hamilton, Tauranga, Greater Wellington and Christchurch grew by almost 20,000 people annually during the same period.
Building consent figures hit a high last year, most of the homes are being built in cities.
The share of new townhouses, units and flats in those figures increased from about 10 percent in 2011 to about 55 percent in 2022.
The share of standalone houses decreased from approximately three quarters of consents to about a third.
By 2043 an extra 208,100 households are expected to be needed in Auckland; 22,000 in Hamilton; 20,700 in Tauranga; and 28,400 in Christchurch.
In Wellington city and Hutt Valley the number of dwellings will increase by 20 percent, in Porirua - by a quarter.
