It's one of the fastest-growing sources of greenhouse gas pollution. And the airline industry's massive emissions of global-warming gases are completely unregulated.
But that might be about to change -- unless the airlines manage to sabotage the process at the tail end. Last week, after years of unreasonable delay, the U.S. Environmental Protection Agency finally announced it will complete the first step toward reducing aircraft greenhouse gas emissions by April 2015.
On that date, EPA will propose an "endangerment finding" under the Clean Air Act, to be finalized within another year, which will determine whether aircraft carbon emissions threaten human health and welfare.
That question can be answered only one way: Of course aviation emissions are dangerous. Five long years ago, the EPA confirmed what the world has known for decades: Man-made greenhouse gases are already disrupting our climate and will inflict catastrophic warming unless we take major steps to cut pollution.
The urgent need for action was recently underscored by a terrifying new scientific report from the United Nations, which found that greenhouse gas pollution is growing so rapidly that the world could soon suffer "severe, pervasive and irreversible impacts."
Airplane carbon plays a large and growing part in the unfolding disaster. The airline industry currently accounts for 11 percent of all U.S. transportation-related emissions and about 4 percent of total U.S. emissions. Emissions are rising 3 to 5 percent annually, on a path to quadrupling by mid-century.
Globally, air travel could contribute as much as 15 percent of all man-made emissions by 2050 if air travel and freight demand follows these growth projections.
Of course aviation carbon emissions endanger us, and of course EPA must take the next step and reduce this pollution. Once the endangerment finding becomes final, the Clean Air Act leaves EPA no further choice in the matter. In fact, EPA should have issued aircraft carbon reduction regulations years ago.
And cutting aircraft carbon pollution is easy to do. Even today, the most efficient airlines emit 26 percent less carbon than the least efficient ones. Applying current and in-design carbon-reduction technology to the planes we fly today and those on the drawing board is low-hanging fruit in the carbon fight.
So when will EPA set standards to make this happen? Here, EPA remains vexingly vague. The agency says it expects the International Civil Aviation Organization (ICAO) to set carbon standards in 2016, which EPA then expects to follow for the U.S.
Will ICAO, which hasn't done a thing about greenhouse gases for nearly two decades, actually produce carbon standards by 2016? It's much more likely now. EPA's acting on its own constitutes the first real pressure for international action since the airline industry -- prominently led by the U.S. and with the Obama administration's active assistance -- sabotaged Europe's fight to include international flights in its carbon trading scheme.
But having to operate under different standards in different countries, a nearly certain outcome now that EPA is moving ahead, is enough of a threat to the airline industry that it may allow ICAO to proceed this time. After all, if there are no ICAO standards, EPA must and will go it alone.
What would ICAO standards do? Alas, unless EPA holds to its mission to keep our planet livable for all of us, that's where the good news may come to an end. There are grave concerns that the standards under secret consideration at ICAO will become a Trojan Horse that will not reduce emissions.
If that happens and if EPA then makes the mistake of adopting do-nothing measures, the airline industry will have successfully rigged the deal and wrecked the plan. Though EPA would surely be sued -- after all, U.S. law requires pollution reduction standards to actually reduce pollution -- those legal proceedings would once again delay action and cost us precious years we cannot afford to lose.
So which part of the Obama administration will win out? Will it be the forces in the administration that finally green-lighted EPA's work on aircraft carbon? Or the side that kowtows to the airline industry, allowing it to stymie any effort to control the carbon monsters in the sky?
If the President wants a legacy of climate action, he will have to choose the right side soon.