By Robert McLachlan* of 
Comment: After two years of entry restrictions, New Zealand is re-opening its borders. Already, New Zealanders can re-enter the country without quarantine; they will be followed by Australians on 12 April and the rest of the world on 1 May.
Photo: AFP
Families will be able to reunite. Grandparents will be able to visit new grandchildren for the first time. And the tourist industry is very keen to get cracking again.
But as international travel resumes, we should make sure flying doesn't return to 2019 levels. That was incompatible with a safe climate and global emissions targets. At 2019 levels, there would be just 10 years of flying left in the carbon budget for 1.5degC.
In 2019, New Zealand aviation emissions were 4.9 million tonnes of carbon dioxide (CO₂), having risen 43 percent since 2014 to become the sixth highest in the world per capita. At 12 percent of New Zealand's total CO₂ emissions, they were a substantial chunk to be dealt with.
Domestic aviation is included in New Zealand's Emissions Trading Scheme (NZETS) and carbon budgets. International aviation emissions are measured but are not included in national targets or regulations.
Last November, at COP26 in Glasgow, New Zealand joined the International Aviation Climate Ambition Coalition and committed to: Preparing up-to-date state action plans detailing ambitious and concrete national action to reduce aviation emissions and submitting these plans to ICAO [International Civil Aviation Organisation] well in advance of the 41st ICAO assembly.
This assembly of the UN's International Civil Aviation Organisation will take place in September 2022.
How to cut aviation emissions
In a new report, economist Paul Callister and I look at all the options. What would "ambitious and concrete action" to reduce aviation emissions look like for New Zealand?
Change is in the air. There are new proposals for net-zero aviation by 2050 from the EU, the UK, the International Air Transport Association, the International Energy Association, and Air New Zealand.
In New Zealand, a two-seater electric plane with a 130km range crossed the Cook Strait for the first time in November last year. Unfortunately, its larger cousins won't be here soon enough or in large enough numbers to affect emissions overall.
"We landed with 40% remaining."
— Bloomberg Quicktake (@Quicktake) November 2, 2021
For the first time ever, an electric plane crossed New Zealand’s Cook Strait, which separates the country’s North and South Islands. @electricairline’s flight coincided with #COP26 in Glasgow to raise awareness about greener flying pic.twitter.com/mvAkQ2YluO
Despite the media attention on electric and hydrogen aircraft, they do not feature strongly in New Zealand's plans. Larger electric aircraft don't exist yet and we need to act sooner than they will become available.
Better fuel technology
Offsetting (by planting trees, for example) is a temporary fix. It transfers risk to the next generation and does not get at the root of the problem, which is burning fossil fuels. Most pathways do not rely on much offsetting.
For the next few decades, emissions will be determined by traffic volumes, efficiency and sustainable aviation fuel.
Efficiency can be encouraged by using the most fuel-efficient planes (and possibly banning the others), filling them as much as possible, flying efficiently and increasing the price of fuel through a carbon charge or a sustainable fuel mandate, or both.
Sustainable aviation fuel is the main technological solution on the table. By 2035, New Zealand could conceivably build two $520 million wood-based biofuel plants, producing 57m litres a year each, and one 100MW e-fuel plant producing 40m litres a year. Together they would provide 8 percent of New Zealand's jet fuel at 2019 levels of demand.
However, neither of these technologies are yet in commercial use; the first demonstration plants are only now under construction. The uncertainties are large.
Traffic volumes are affected by price and regulation. Industry projections of very high growth (up to 120 percent by 2050) are not compatible with the Paris Agreement.
The present free ride for international aviation (no GST, no carbon charge, no fuel tax) is an obstacle. But now that the EU is considering a tax on jet fuel, this could change.
Traffic volumes are affected by price and regulation, but high growth is not compatible with the Paris Agreement, Robert McLachlan writes. Photo: 123RF
Curbing frequent flying
Flying less is the main remaining tool in the toolkit. Air travel is strikingly unevenly distributed. In Europe, 90 percent of households have aviation emissions of 0.1 tonnes of CO₂ per person per year (equivalent to one Auckland-Sydney return trip every four years); 9 percent emit 0.8 tonnes (Auckland-LA every two years); and the top 1 percent, 22.6 tonnes (Auckland-London six times a year).
So less frequent flying, especially by the hyper-mobile, has to be part of the solution. Non-flyers cannot reduce their aviation emissions. The Jump campaign asks people to limit flights to one 1500km return flight every three years, a level derived from a study of urban lifestyles compatible with 1.5degC.
People in many countries are being asked to limit their long-distance travel. Photo: 123RF
The natural experiment of the Covid-19 pandemic prompts the question of how essential such frequent flying is to wellbeing.
Stats New Zealand monitors wellbeing following international guidelines. While 81 percent of the population reported high overall life satisfaction in 2018, this rose to 86 percent in 2021. People adopted substitutes for international travel, including telecommunications, domestic tourism and local tourism.
#BackYourBackyard: It's a tough time for travel, but we have an opportunity to help, and discover the best close-to-home travel experiences at the same time https://t.co/aOUS58QYwY pic.twitter.com/NwnR8LEFEK
— Stuff (@NZStuff) March 13, 2020
The economy also grew, up 3.4 percent from 2019 to 2021.
However, there are confounding factors, namely the government stimulus, social solidarity and knowledge of the health risks of travel.
A recent UK study considers the role of curbing excess energy consumption in a fair transition. After comparing ten possible definitions of "excess", they conclude that: excess is whatever people can agree it is, based on ideas of "fairness" and "just" levels of consumption that can be rationalised, defended and justified to others … any policies that are used to target excess consumption and excessive consumers must be similarly reasonable and justifiable, based on the principles of deliberative democracy and exploring options, impacts and fairness with members of the public.
Two key events of the past decade reinforce the urgency of the situation. The first is the proven ability of the New Zealand aviation industry to increase emissions at a staggering rate when unregulated, as observed from 2014 to 2019.
The second is Covid-19. Ensuring that aviation emissions remain permanently well below 2019 levels will make the longer-term task significantly easier.
*Robert McLachlan is Professor in Applied Mathematics at Massey University
