Auckland professor says Kiwis should quit air travel to protect the environment

A grassroots movement calling for Kiwis to stay firmly on the ground is taking flight.

It's asking everyday travellers to keep out of the skies in a bid to protect the environment.

Auckland physicist Professor Shaun Hendy decided to give up air travel for a year to limit his carbon footprint.

"It was adding up the carbon emissions that I was responsible for," he told Newshub. "I was about three times the average Kiwi as an academic travelling to conferences."

He documented his travels along the way, from stormy drama on the Cook Strait ferry to a bus trip through Bulls on his way home from Wellington.

"Lovely trip, it does take a day so you've got to commit to it."

The cost of flying is going down, but the cost to the environment is becoming much clearer.

If you fly the 496km between Auckland and Wellington, you emit around 150kg of carbon dioxide equivalent. A medium-sized car making the same journey emits about a third less, while a bus, train and electric car all have significantly lower emissions - just under 55kg between all three of them.

Air travel is vital to the country's trade, investment and tourism, and new technology is making it more efficient. But there's no disputing the boom in air travel is having an impact on climate.

"Per kilometre, flying in a plane puts out more carbon dioxide than pretty much every other form of travel," Victoria University climate scientist James Renwick said.

Stats NZ data shows New Zealand residents took more than 3 million flights in 2018. One Auckland passenger flew 639,000km - the equivalent of 15 circuits around the Earth.

But if you're not ready to swap the skies for the roads yet, there are some alternatives.

Both Air New Zealand and Jetstar have a carbon buyback scheme in which travellers pay a small fee to offset the emissions generated by their ticket.

Aviation commentator Irene King said it's a positive step, but the airlines and manufacturers need to make greener planes.

"It's supply and demand, and we know the fuel prices will go up, and so there's massive incentive toward greater engine efficiency."

If the movement takes off, flying from one location to the other could soon be as frowned upon as using plastic bags.