The Environmental Protection Agency formally declared Monday after years of review that greenhouse gas emissions from airplane engines cause climate change and endanger human health and the environment, just as exhaust fumes from cars do, and that they likewise need to be controlled.

U.S. aircraft emit roughly 12 percent of greenhouse gas emissions from transportation, and 29 percent of emissions from all the world's planes. With carbon controls in place or planned on the biggest sources—vehicles and power plants—growing pollution from aviation "is an important element" in tackling the climate crisis, said Janet McCabe, a top EPA official.

The action taken today completes the first phase of bringing the problem to heel under the Clean Air Act. Eventually, it is expected to lead to specific engine emission regulations that are at least as stringent as those being negotiated through the International Civil Aviation Organization (ICAO), a United Nations body that includes the United States. Fixing the problem will be costly, so unless all nations take action in a coordinated way, the world's passenger airlines might be jostled about by turbulent economic winds.

ICAO's members will vote in September on a proposal to cap climate pollution from industry worldwide with "an innovative market based mechanism to ensure that airlines achieve net carbon neutral growth from 2020," said Annie Petsonk of the Environmental Defense Fund.

The EPA's findings include not only carbon dioxide, the principal greenhouse gas, but also several other compounds, some of them very potent agents of global warming.

More efficient engines are just one way to address the problem. Better air traffic control, for example, can also help reduce fuel use. So can using alternative fuels.

David Doniger of the Natural Resources Defense Council said that the climate problem "requires an all-encompassing approach," and that commercial jets cannot go unregulated. Airlines account for 2 percent of greenhouse gas emissions around the world, a share that is expected to grow to 3 percent by 2050. In absolute terms, that might mean a tripling of emissions from commercial jets. (Small piston-driven planes and military aircraft aren't covered by the EPA's approach.)

In June, the group released a survey of airlines's performance in one measure of action against global warming, the use of renewable biofuels. The leaders among19 airlines, representing two-thirds of the industry, included Air France/Royal Dutch (KLM), British Airways, Cathay Pacific, Scandinavian (SAS), South African Airlines and United.