Carbon offsets alone won’t make flying climate-friendly

Jet A-1 is a difficult substance to replace. It has at least 60 times the amount of energy as the batteries used in electric cars. It's bad for the climate. As the aviation industry has gradually climbed aboard global pledges to get rid of carbon emissions, it has mostly promised to make up for its damage elsewhere, through offsets that might involve planting trees, restoring wetlands, or paying people to preserve habitats that otherwise would have been destroyed. Most of the planet-warming effects of flying aren't from carbon dioxide.

There is a cascade of atoms in the troposphere. The initial combustion releases a shower of particles. At those frigid heights, some of the particles become nuclei around which condensation gathers and then quickly freezes, helping to produce high altitude clouds. Nitrogen molecule set off a chain of reactions that produce ozone and destroy free-floating atmospheric methane in the presence of the Sun's rays. It's difficult to pin down what this chemistry means. The methane destruction helps cool the earth. Some people warm it. Tens of thousands of planes streaking across the sky each day are dependent on the atmospheric conditions for each flight.

Overall, the warming effects add up. In an analysis published last year, an international team of researchers pinned 3.5 percent of total warming in 2011 on aviation alone—which may sound small, but the number has been growing fast. The authors found that roughly two-thirds of warming due to aviation at that time was caused by all of those factors that aren’t CO₂ emissions. Advertisement

Some scientists think that the term "carbon-neutral" doesn't mean much when it comes to flying jets. If the aviation industry wants to help meet global temperature goals, it's better to think in terms of "climate neutral" Rules for more efficient flying, new technologies like low-carbon fuels and batteries, and more intensive efforts to remove carbon from the air are some of the ways to get there. Less flying is what I mean. She says it would take an enormous effort to meet the climate neutrality framework with technology fixes and no lifestyle changes.

The industry has focused on offsetting carbon. It is easy to measure how carbon dioxide is converted into jet fuel emissions. It's based on knowledge of fuels and engines. Airlines already make those calculations and let customers see their damage, and often pay a little extra to offset those emissions through partner programs. Expecting continued growth in demand for aviation, members of the International Civil Aviation Organization have pledged to hold their net carbon emissions to a certain level. Many of the offset programs that airlines partner with underestimate the amount of carbon that they successfully store, according to investigations. They are all about carbon.

It's difficult to account for all the non-CO 2 factors. The atmospheric chemistry is dependent on temperature and humidity. The greatest uncertainty is the possible behavior of the tendrils behind the planes. David Lee is an atmospheric scientist at Manchester Metropolitan University who studies aviation emissions. They can hang around as clouds if the air is humid and cool. The time of day is one of the factors. The clouds reflect the sun's rays to keep the Earth cool. They can cause heat at night.