Cures exists for ‘flight-shame’ – if we look hard enough

Qantas has just test-flown the world’s longest commercial air-route – 16,500 kilometres from New York non-stop to Sydney. There were only 60 passengers aboard the Boeing 787, all in business class, because the plane needed all the rest of the weight for fuel.

I don’t think Greta Thunberg would have been pleased.

There is a Swedish neologism, ‘‘flygskam’’, that has gained currency among environmental activists in Europe. It means ‘‘flight-shame’’, which is the emotion righteous people should feel if they take a plane trip and contribute to global heating.

Thunberg took a sail-boat across the Atlantic because the fuel that is burned to get each airline passenger across that ocean causes warming equivalent to about 10 per cent of the average Swede’s annual carbon footprint.

Aviation accounts for about 2.5 per cent of human-caused greenhouse gas emissions at the moment, but the contrails the planes leave in the stratosphere turn into cirrus clouds that reflect heat back to the surface and that causes an equal amount of heating.

So 5 per cent of current warming is already due to aviation and industry representatives estimate the number of people flying annually will almost double, to 8.2 billion, in the next 20 years. By then flying will have grown to 10 per cent of the global heating problem, or even more if we have made good progress on cutting our other emissions. So must we stop flying?

That’s not the way we deal with other climate-related transport problems. We haven’t abolished cars, we have just worked on ways of reducing and ultimately eliminating the emissions associated with them. Electric cars now lead the field, but other alternatives may emerge. By contrast, we are told, there are no alternatives available for aviation.

People have been nibbling around the fringes of the fuel problem, but biofuel won’t cut it. It would take an area the size of Australia to grow the plants needed as feedstock for the fuel the aviation industry consumes. Batteries are too heavy to use in electric planes and there’s no solution for the contrail problem. We’ll just have to stop flying.

Not necessarily. The problem has been neglected, because the aviation industry was too lazy or stupid to start preparing for a future that more attentive people could see 20 years ago. But the fuel problem is not insoluble. In fact, it has already been solved. The solution just needs to be scaled up.

People have been working on direct air capture of carbon dioxide for more than a decade and the leader in the field, David Keith’s Carbon Engineering, has had a pilot plant running in British Columbia for the past three years.

Keith’s business model involves combining his captured carbon dioxide with hydrogen, produced from water by electrolysis. The electricity for both processes comes from solar power and the final product is a high-octane fuel suitable for use in aircraft.

It emits carbon dioxide when you burn it, of course, but it’s the same carbon dioxide you extracted from the air at the start. The fuel is carbon-neutral. Scaling production up would take a long time and cost a lot, but it would also lower the price to a commercially viable level.

The contrails and the cirrus clouds in the stratosphere are a considerably harder problem, but there are measures that would help.

The planes are flying so high for two reasons. The air is less dense up there, so you don’t use so much fuel pushing through it. But the main reason, especially for passenger planes, is that there is much less turbulence in the stratosphere than in the lower atmosphere. If the planes flew there, everybody’s sickbag would be on their knee.

So what can you do about it? Well, contrails only form in air masses with high humidity and therefore only affect 10-20 per cent of flights. With adequate information, most of those flights could simply fly around them. Alternatively, fly below 25,000 feet for that section of the flight and contrails won’t form anyway.

It will be more turbulent down there, so in the long run we should be building aircraft that damp out most of the turbulence. This is probably best achieved by ducted flows of air that counter any sudden changes of altitude or attitude, but if aircraft designers started incorporating such ducts into their designs today, they’d only come into regular use in about 15 years.

So the order of business is first, carbon-neutral fuels (half the problem solved); second, avoiding air masses with high humidity (another quarter solved); and finally, turbulence-damping aircraft (most of the rest done).

By the way, how is Thunberg getting home again?

‘‘Great for Timaru.’’ Rowena McLintock