It’s been seven years since I set foot on a plane. I have not missed flying: not the sock-footed security drill, the shrinking seats or the fumes lingering in lungs and luggage.

Now, it seems, I have another reason to celebrate my extended grounding; I’ve managed effortlessly to avoid one of the biggest potential contributors to my carbon footprint (the annual total of greenhouse gas emissions from all activities).

Planes might seem at first like a minor part of global carbon emissions; estimates range from 2 to 5 percent. But aviation’s impact reaches high into the atmosphere where the climate effects of emissions are magnified. And planes spew out far more than CO2; they leave in their wake black carbon particles, nitrous oxide, sulfur oxide and contrails of water vapor – all of which can trap heat radiating up from the lower atmosphere.

Air travel can easily come to dominate a person’s carbon footprint. A single cross-country flight represents a tenth or more of what an American typically generates in carbon emissions each year (and more than the total annual emissions of many people living in developing nations). Bill Hemmings, aviation director for the European nonprofit Transport & Environment, describes flying as “the fastest and cheapest way to fry the planet.”

The cheap part is worth highlighting. An international convention dating back to 1944 prevents countries from assessing a jet fuel tax or value-added tax on international flights so adjusting the cost of air travel upward to account for its planetary pollution is not currently feasible. The European Union attempted a measure along these lines in 2008 and met with a forcible pushback from airlines and other countries (including the U.S.).

Incredibly, the Paris Climate Accord gave a pass to both aviation and shipping, leaving the airline industry to come up with its own approach to reduce emissions. So as other sectors cut back emissions over the next three decades, the share of global CO2 emissions from just these two sectors could rise to 40 percent, according to reporting by Fred Pearce in Yale’s e360. Members of the International Civil Aviation Organization, representing 191 countries, did sign an accord in 2016 designed to limit future emissions, but the mandatory phase of that plan does not even take effect until 2027.

Meanwhile, the trajectory for growth in annual airline travel is rising more steeply than a plane taking off. By 2035, annual air travel is expected to double as a growing middle class – in places like Asia – take to the air.

It’s hard to imagine how airport infrastructure will handle that growth. At settings like the Portland Jetport and Boston’s Logan Airport, little acreage is left to expand runways. In fact, sea-level rise is already gnawing away at many airport properties in low-lying coastal settings.

Projections for buoyant growth overlook an irony that complicates the bumpy relationship between air travel and climate change. Plane flights, of which there are 13,000-16,000 at any given moment worldwide, blanket the earth in heat-trapping emissions. (To help visualize this density of flights, view NASA’s video “A Day in the Life of Air Traffic over the United States” on YouTube.)

A warming planet, in turn, undermines the efficiency and convenience of flying:

• Extreme heat forces the grounding of planes – and not just due to melting tarmac. High heat makes lift-off more difficult, necessitating longer runways or lighter loads. Weight restrictions make aviation less efficient and more costly.

• Airports get especially hot during heat waves, being urban heat islands (settings with abundant asphalt and few shading trees).

• The shifting jet stream patterns associated with climate change are expected to markedly increase turbulence – up 150 percent within decades, by one estimate.

• Greater turbulence, coupled with the intense storms associated with climate change, will cause more re-routings, cancellations and delays.

It’s odd that projections for climate-induced upheaval to aviation don’t seem to affect predictions for air travel’s explosive growth. Are passenger numbers really going to double in two decades even as travelers encounter exponentially more congestion, disruptions, delays and turbulence? Just thinking about that scenario leaves me feeling air sick.

ABOUT THE WRITER

MARINA SCHAUFFLER is a freelance journalist and editor whose work is online at www.naturalchoices.com.