Lawns, a big contributor to climate change

By on October 30, 2022 0

There is a call for a radical and fundamental overhaul of the parks and quarter-acre grassy sections that many Kiwis yearn for.

Professor Len Gillman from Auckland University of Technology says it’s because of climate change.

“And most people don’t really understand how bad it’s going to be,” he said.

He helped write a new research paper, “Calling Time on the Imperial Lawn”.

His findings show that while lawns are often thought to sequester carbon from the atmosphere, this is not the case, once mowing, fertilizing and watering are taken into account.

He says mowed grass, in almost all cases, emits carbon.

Over 20 years, it could reach 43.9 tons of carbon equivalent per hectare, but other estimates place it much higher.

The newspaper calls for change both at home and on public lands, digging up any unused lawn and putting it under trees instead is the answer.

“We have to plant, we have to reduce emissions, it’s essential,” Gillman said.

The mowed grass is “ubiquitous and everywhere”, he said.

“For example, there are about 16 million hectares in the United States alone, which is the size of England and Belgium combined,” he told 1News.

“Even if we only plant a third of the grass in the world’s cities, we can absorb 6,000 million tonnes of carbon dioxide over two decades, so that’s a lot.”

He said while lawns are desirable to many, often much goes unused.

“The roadsides, the bits of parkland that are kind of tucked away in a corner somewhere that no one ever uses, there’s a lot of grass that could actually be planted and we have to plant it.”

His article says it is imperative that governing bodies put policies and incentives in place.

Auckland Council said it could not order people what to do in their backyards, but could encourage them.

Facilities manager for parks and community facilities, Karl Beaufort, said the council was “100 per cent” in favor of replacing lawns with trees.

“We think that’s a really good thing to explore back home,” he said.

“There is a lot of history around the creation of lawns and the social ranking based on lawns all comes from a British heritage and I think it’s time to start looking to change that and look towards nature New Zealand and what a New Zealand backyard actually is. look like.”

He spoke to 1News from a ‘low mow’ test patch from the council.

Grass on reserve land is removed from the regular mowing schedule and instead cut twice a year.

He said the results of this can be used to inform politicians about what mowing works best on municipal land and how the council can reduce its carbon footprint.

“And if people are happy with that, and it’s socially acceptable, we think that’s a win,” he said.

Howell Davies is the Auckland Council’s Senior Advisor for Urban Forests.

“Our council has an urban Ngahere (forest) strategy which seeks to increase our overall forest cover from 18% to 30% currently,” Davies said.

“And we are really counting on landowners and council to be involved in this ambitious overall goal, so conserving trees and planting more trees on private property is as important as the council’s role of planting trees on land. advice.”

In planting his seed for change, AUT Professor Len Gillman said councils around the world needed to do more.

“They have to take a much bigger lead, and that’s local government around the world,” he said.

“Incentives that make people think and motivate them to do so.”

What the study says

  • The rate of carbon emissions from mowing depends on the size and type of mower and how often it is used, but 1.1 to 5.5 million tons of carbon could be emitted in the United States alone by mowing each year.
  • Adding fertilizer causes nitrous oxide emissions.
  • Watering lawns causes emissions due to the energy needed to capture, pump and move water.
  • It will take a fundamental shift in what people perceive as desirable and usable in parks, but the climate crisis is of such magnitude that all possible options must be considered.