How to shave 200kg a year off your carbon footprint with one small change

Christchurch’s addiction to cars is killing us.

The city – where 76% of people commute by car – has the highest vehicle emissions-related death rate of anywhere in the country.

But the winds of change are blowing, and Christchurch has a sprawling, rapidly-growing network of cycleways which make getting around by bike easier than ever.

Stuff has launched a new Better by Bike campaign this spring, aimed at getting more Ōtautahi commuters out of their cars and onto their bikes.

New Zealand is at a critical point in the climate crisis, but experts say even a small change – swapping the daily commute from car to bike just one day a week – can slash 200kg of carbon a year from our own carbon footprint.

The latest Health and Air Pollution in New Zealand study, released in June, found health problems worsened by air pollution contributed to more than 3300 premature deaths, and cost NZ $15.6 billion in a single year.

The report, which focused on the year 2016, was for the first time able to measure the health impacts of nitrogen dioxide, a toxic gas from petrol and diesel engines.

It showed nearly two-thirds of those deaths could be attributed to vehicle emissions.

Invercargill topped the death-rate rankings for air pollution from vehicle exhaust, home fireplaces, and industry combined, followed by Christchurch.

But Christchurch held the dubious honour of highest death rate from traffic exhaust alone – with residents nearly three times more likely to die prematurely from air pollution than Wellingtonians.

Of an estimated 316 Christchurch residents who had traffic fumes contribute to their premature deaths that year, 287 could be credited to nitrogen dioxide, and 29 to other tiny vehicle particles.

Nitrogen dioxide causes respiratory and cardiovascular system damage – making people more prone to infections and conditions like asthma – while particulates are known to cause cancer.

The findings even have Te Mana Ora – Health NZ’s Canterbury public health service – concerned, medical officer of health Cheryl Brunton said.

“We have known for some time that we have an air quality issue in Christchurch, mainly during winter and caused largely by home heating and vehicle emissions.”

They had been working closely with regional council Environment Canterbury (ECan) and others for years, she said, on strategies to reduce the levels of those pollutants, and the risks to health.

“That work is ongoing, and we will continue to support initiatives that lead to cleaner air.”

ECan is responsible for both maintaining air quality, and planning the region’s transport.

Senior strategy manager Jesse Burgess said the total greenhouse gas emissions from Canterbury’s regional transport network sat at around 1.8 million tonnes of carbon dioxide equivalent each year.

“Some areas of the city may be worse than others.”

There were many factors which could influence levels of both particulate matter and nitrogen dioxide, he said, including vehicle age, brake and tyre quality, and fuel type.

“For transport emissions, urban design and road environment is an important factor, for example tall buildings on both sides of the road, where there are a lot of cars or a really congested intersection.

“In these areas, concentrations from motor vehicles will be higher.”

Weather was also a critical factor, “especially cool, still days”, and wintertime in Christchurch was still the worst time of year for air pollution, he said.

“Our air quality scientists have a good understanding of how concentrations have been changing over time and concentrations, in general, are improving.”

Burgess said ECan was hard at work tackling both home heating and transport emissions.

There had been big pushes to get more Cantabrians using public transport, including a $2 bus fare trial kicking off in February, and councils across greater Christchurch were adding more electric or low-emission vehicles to their fleets.

ECan expected to have 40% of the vehicles in its metro bus fleet electric or low emissions by mid-2023.

“Even small improvements in air quality can make a difference to health and this is really important at the moment given the pressure on the health system, especially in the areas that support respiratory health.”

But individuals and their choices could play a big part too.

Auckland Council’s climate action solutions manager Adrian Feasey – who helped develop the Future Fit carbon footprint calculator – said one of the best things people in Christchurch could do to cut their emissions was changing the way they travelled.

Transport made up around 54% of greater Christchurch’s total greenhouse gas emissions, he said.

“Even small changes can make a big difference. Swapping short trips for walking and cycling can reduce your carbon footprint, save you money and help you stay healthy.”

It could also help meet New Zealand’s very first emissions budget, released in May. The Government wants Kiwis to travel 20% fewer kilometres in vehicles by 2035, instead walking, cycling, or using public transport, to limit the impacts of climate change.

Try cycling once a week

The average commute in Christchurch is 8km each way – or 16km a day for a return trip – according to Statistics NZ data.

“Over a year these numbers and our behaviours can really add up.”

Based on average commute distance and average engine size, each Christchurch commuter who travelled by car was responsible for emitting 1018kg of carbon dioxide each year, Feasey said.

“That’s equivalent to the [carbon dioxide] taken up by 69 native trees every year.

“If you live in Christchurch and you normally drive to work, cycling to work every day instead will reduce your emissions by 1018kg [carbon dioxide] per year.”

But Feasey said even cycling to work just once a week would reduce your emissions of carbon dioxide by 203.5kg a year.

“If we all make small changes our collective effort can have a big impact on our climate goals.”