Look To The Skies

Only a simpleton would deny the reality of climate change. Whether we are reading almost daily about wildfires, tornadoes, floods or sea-level rise, we know in our hearts that the future has arrived and will only get worse. Despite that understanding, many of us continue with practices that will only aggravate the problem.

One of the most egregious is flying, something I continue to be guilty of, usually twice a year. Since people are not inclined to stop visiting loved ones who live far away, or taking that much-needed winter getaway, are we doomed then to simply add to the greenhouse gas emissions that are fueling climate change?

Gwynne Dyer offers his perspective both on the scope of the problem and a possible partial answer to it through new technology:

Aviation accounts for around 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 in reality five per cent of current warming is already due to aviation, and industry representatives estimate that 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.

Should we despair? Dyer suggests there are solutions that don't entail an outright stop to flying, but they are ones that the aviation industry has shown little interest in, corporate inertia being what it is.

A number of people have been working on DAC (Direct Air Capture of carbon dioxide) for more than a decade already, 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 bring the price down to a commercially viable level.

The problem with the heat-reflection caused by contrails also has some mitigation-avenues available:

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 down there, they’d be bouncing around half the time, and everybody’s sick-bag 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 to 20 per cent of flights. With adequate information, most of those flights could simply fly around them. Alternatively, fly below 7,600 metres 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 automatically damp out most of the turbulence. This is probably best achieved by ducted flows of air that instantly 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’ time.

One should always be wary of deus ex machina solutions. However, the approach suggested by Dyer surely deserves consideration as one of the strategies needed as the climate crisis continues to worsen.