AVIATION ACCOUNTS for only 2 or 3 percent of the world greenhouse gas emissions contributing to climate change. But that share is rising as air travel increases. So in 2012, the European Union will bring airlines under its carbon cap, requiring them to reduce their emissions by 5 percent over the next decade or to pay for not doing so.

Europe, though, doesn’t want to restrict the greenhouse gases planes produce only while flying over E.U. nations. The bloc also wants to regulate aircraft flying to or from Europe. Last week, a group of U.S. airlines argued before the European Court of Justice that Europe doesn’t have the authority to do so — and that the policy would make air travel to Europe more expensive. The Chinese and U.S. governments also are pressing back. U.S. officials say that Europe is pursuing a worthy goal the wrong way — unilaterally instead of through international negotiation.

But years of negotiation haven’t come close to producing accord on emissions rules, E.U. officials note. They also, understandably, don’t think that European airlines should pay more than Chinese or American carriers.

Is there a way to square this circle without triggering rounds of counterproductive trade retaliation and shattering a long record of international cooperation on civil aviation? With the E.U. law scheduled to come into force in a matter of months, the Obama administration should agree, and press others to agree, that the Europeans have good reason to want to account for the pollution of all aircraft servicing their market, even if that means allowing them to count more than the emissions produced in European airspace. The Europeans should also have some assurance that an agreement can be struck in a reasonable amount of time. In return, the E.U. should be willing to delay implementation of its rules and perhaps to develop its own flexibility on how and where it enforces them.

An accord could solve not only this particular dispute but also settle some long-standing questions about how carbon rules apply internationally — a good thing if, as everyone should hope, more countries begin to implement market-based policies to combat climate change.