Wednesday, July 6, 2022

Urban sprawl threatens our prime farmland

Having studied major urban centres, Dr Daniel Rutledge can see glimpses of the future for places like Hamilton and Auckland. Like so many places he has studied, Rutledge sees new housing and business tracking along the path of a motorway network. And in many cases that growth is stripping farming of some of its best soil. Rutledge, an American who works for Landcare Research in Hamilton, said New Zealanders were not alone in having to make hard choices about sustainability. He was elaborating on papers from the Royal Society exploring big areas, such as how many people and to what standard of living this country can support sustainably.

Research has shown New Zealanders would need at least two Earth planets to sustain our current lifestyles, compared to a “fair Earth share” of one. Some estimates put this number as high as five Earths, the Royal Society said.

The papers, produced with the society’s help, show sustainability is not a simple trade-off between economy and the natural environment.

The research explores a number of areas where sustainability is a factor and related problems might “constrain our ability to create ever-more wellbeing”, such as climate change, food production, water quality, native biodiversity, transport and fisheries.

Rutledge, a contributor to the research, said questions about growth and environmental limits were particularly difficult in relation to Auckland.

“I think it’s a very tough question and there are a lot of consequences for it. The particular lifestyle that New Zealanders have come to enjoy is very culturally engrained and that would be difficult to change,” he said.

Rutledge is familiar with a very different way of living in the Netherlands. When the family of his Dutch wife visits New Zealand they invariably comment on the amount of space around them.

The pattern of urban development would often be based on assumptions about the future, from a “pure physical standpoint” and also factors such as the value of land, he said.

It would seem there was no turning back from advanced urbanisation and the associated environmental “lock-in”.

In a NZ context, Rutledge sees the gradual joining of Auckland and Hamilton and can’t help thinking of what he has seen previously in American cities.

“From my research in Detroit, once you get that highway network in place, once you’ve put the travel times into an acceptable range, they will make those personal decisions for their lifestyle,” he said.

People who might have previously objected to a 45-minute commute would be prepared to travel longer distances once they could hop on a two-lane highway. This wouldl have ramifications for the future of farms along highway corridors between Auckland and Hamilton.

“Often times, most of our high-class land – 1, 2, 3 class land – is disproportionately located closer to our major urban centres,” Rutledge said. “We’re now going to be facing some hard decisions if we want to continue, and expect, urban growth in these areas.”

The answers were not necessarily a simple choice between greater population density and less room for other land uses, he said.

“You go the Netherlands and it’s all very high density, a lot of townhouses and apartments – well controlled town planning and transportation – but in Belgium it’s a lot more like what I’m used to in the States or in NZ. So it’s just that sort of cultural difference.”

That said, Rutledge didn’t think NZ farmers had a common set of shortcomings when it came to sustainability.

More pressing influences on farmers’ behaviour were “game-changer” global issues, such as the entire structure of global trade.

“An individual farmer in NZ is going to have to be savvy about what those could be and have a better planning horizon for understanding what might be coming and how we can adapt, or plan appropriately in more pro-active steps,” he said.

The Royal Society papers on the subject also contain a contribution by Landcare Research’s governance and policy leader Dr Suzie Greenhalgh, who has been involved with the Land and Water Forum process.

Greenhalgh launched the papers a fortnight ago by saying setting environmental limits and trading within those limits was only one approach to dealing with constraints in our natural resources.

The senior academic identified agriculture as an area where the sustainability balance was improving, but also one that was due for improvement.

Increases in pastoral agriculture had resulted in a seven-fold increase in the use of nitrogenous fertiliser over the past 20 years and the volume of water allocated for irrigation had reached or exceeded current limits in many areas. Both of these were affecting freshwater lakes, rivers and streams, she said.

NZ produced enough calories for 20 million people and enough protein for 45m people, she said. The overall wellbeing the country could generate using the finite resources available depended upon how those resources were managed and used.

For example, shifting dairying off leaching-prone land on to more suitable land could reduce overall nitrogen pollution without reducing overall output and farm profitability.

A study to model land use north of Lake Taupo found nitrate leaching could be reduced by 8% and soil erosion by 14% with no change to farm income and food, wool and wood production by moving dairying off leaching-prone land.

Greenhalgh said despite options for better performance, progress towards better use of those resources was slow in many cases.

Some progress was being made on decoupling economic growth from emissions. NZ’s economy had grown 68% over the past 20 years, whereas greenhouse gas emissions had increased by only 20%.

“However, this progress is not rapid enough yet to halt the growth of our overall greenhouse gas emissions, despite our extensive potential supplies of renewable energy,” she said. 

  • Before joining Landcare Research, Greenhalgh worked at the World Resources Institute, an environmental policy think-tank in Washington, where she worked in areas such as nutrient trading and reverse auctions to improve water quality. She also developed accounting and reporting guidelines for greenhouse gas reduction projects for companies and project developers. 
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