Governments from more than 190 countries on Thursday adopted a measure that for the first time will reduce the climate impact of international jet travel.

The accord adds an exclamation point to a week in which enough countries signed onto the broader Paris climate deal to ensure that it will enter into force later this year.

The aviation plan, the product of years of negotiations, was approved by acclamation at a meeting of the International Civil Aviation Organization, or I.C.A.O., in Montreal.

The measure could force air carriers to take major steps to improve fuel economy in their routes and fleets, very likely accelerating the purchase of newer, more efficient planes.