Early Monday morning a group of climate change activists chained themselves to a runway at London's Heathrow Airport in hopes of persuading the government not to build a proposed additional runway. The problem the activists highlight is worth taking seriously. Between 1990 and 2012, aviation-related greenhouse gas emissions increased 76.1 percent, and now account for around 2 percent of annual global emissions.

The activists' proposed solution, however, is more questionable. The only way to stem the environmental threat posed by airlines, they imply, is through a kind of aviation austerity that reduces opportunities to fly airplanes. But there's a flaw in the activists' analysis: They're struggling to coerce the capitulation of airlines that sympathize with their goals, and have a direct interest in achieving them. Rather than treat the industry as an antagonist, activists would be far better off trying to encourage its ongoing attempts to become more climate-friendly.

Fuel is the single biggest cost that most airlines face, so it shouldn't be a surprise that they have a long track record of pushing plane manufacturers and regulators to help them reduce their dependence. New planes, built with energy-efficient technology, have tended to generate the biggest fuel savings for the industry. Last year, Boeing forecast that 36,770 new airplanes will go into use around the world between 2014 and 2033. Those planes are almost certain to comprise a more fuel- efficient fleet than the one that exists today. The new Boeing 787-9 Dreamliner, for example, burns up to 20 percent less fuel per seat, and 20 percent less emissions, than previous aircrafts of similar size.

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Meanwhile, planes are flying more fuel-efficient routes, thanks to improvements in air traffic control that are being introduced in several countries, including the United States. Better ground operations at airports -- including requirements that planes taxi with only one engine in operation -- promise to produce reductions in fuel use, as do airlines' latest efforts to reduce airplanes' weight, including reductions in the weight of seats and magazines carried in seatback pockets, and the number of bottles of water brought on board to distribute to passengers.

Investments in biofuels also offer long-term hope for low- carbon flying. A widely-cited 2013 study suggests that biofuels could help reduce the industry's annual carbon footprint by around 498 to 845 million tons of CO2 beginning in 2050. By comparison, global aviation-related CO2 emissions were around 600 million tons in 2006.

Thanks to expected growth in global aviation over coming decades, however, that reduction probably still won't be enough to meet the 2009 commitment by the International Air Transport Association, the world's largest airline trade association, to achieve carbon neutral growth by 2020. According to IATA, the number of airline passengers globally will more than double between 2014 and 2034, from 3.3 to 7.3 billion. That's good for airlines' shareholders, and it's the reason Heathrow Airport is hoping for a new runway. But the emissions from all those extra flights will overwhelm the airlines' most strenuous efforts to maximize fuel efficiency.

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The good news is that those shortcomings don't come as a surprise to the industry. When IATA committed its membership to carbon neutral growth (and an aspirational goal of reducing its carbon footprint by 50 percent by 2050, compared to 2005 levels), it also acknowledged that it would need to go beyond improving its technology and tweaking operations, and embrace carbon offsets and emissions trading. In 2013, it urged the International Civil Aviation Organization, the U.N.'s aviation wing, to devise "a global MBM 1/8market-based mechanism 3/8 scheme for international aviation" by 2016. Though it's unlikely that the 2016 deadline for the plan will be met, major airlines and trade associations are pushing hard for it. Meanwhile, Europe's domestic airlines already operate under an emissions trading scheme that could easily be extended to international carriers.

And the tools to make such a plan work are available right now. A 2013 joint analysis by Bloomberg New Energy Finance and the Environmental Defense Fund showed there are enough unused, tradeable emissions allowances (in the form of units from regional and national cap-and-trade programs and voluntary carbon offset projects, to name just two examples) to help the aviation industry meet 30 to 50 percent of its carbon neutral growth goal through 2050. More important, the total annual cost to global aviation companies of using these tools would be relatively insignificant -- less than what U.S. airlines earn from baggage fees. (To be sure, some of that extra cost would be passed onto passengers.)

For global aviation, there are plenty of low-cost opportunities to make good on low-carbon commitments. Rather than blocking runways, climate activists should be seeking ways to help the industry achieve their common goals.

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Adam Minter is an American writer based in Asia, where he covers politics, culture and business.