A new way most planes land at Minneapolis-St. Paul International Airport has brought significant environmental benefits, the Metropolitan Airports Commission reported Monday.

When the Federal Aviation Administration (FAA) rolled out new technology two years ago for arrival procedures — called optimized profile descents, or OPD — officials at the airports commission decided to measure the environmental effects.

The new arrival procedure involves aircraft making one long gradual descent, as opposed to losing altitude in a series of steps until landing. By keeping the plane throttled back and remaining at cruise altitude longer, fuel burn associated with greenhouse gas emissions is reduced, the airports commission said.

But by how much?

The commission’s sleuths studied data provided by Delta Air Lines, the dominant carrier at MSP, as well as Endeavor Air, a Delta subsidiary, Sun Country Airlines and the FAA. The commission became the first airport operator in the nation to do such a study.

Data indicated that airlines burn 2.9 million fewer gallons of fuel per year using the new descent procedure. Put another way, the arriving aircraft annually emit 28,465 fewer metric tons of carbon dioxide.

The MAC released various factoids to bolster its point: The reduction over the past two years is akin to removing 12,000 cars from the road, reducing carbon dioxide emissions from 6.4 million gallons of gas guzzled by cars, and planting 54,186 acres of forest.

“This is good for our system, good for those who travel and for all of us who care about the environment,” said Barry Cooper, Great Lakes regional administrator for the FAA.

But this new system won’t help the airport with its long-standing noise issue with neighbors — much to the disappointment of anti-noise advocates, about a dozen of whom attended a news conference Monday.

“There really is no change, quite frankly, as it relates to noise,” said Chad Leqve, the MAC’s director of environmental programs. Neighbors near the airport probably won’t see much of a difference, he explained, because the benefits begin as aircraft descend, often hundreds of miles from their destination.

Steve Kittleson, co-founder of the neighborhood group MSP FairSkies Coalition, said the environmental improvements are “a great story, but the other half of the story is still noise. This is still unacceptable.”

Kittleson said an analysis led by his group indicated the Twin Cities’ population significantly affected by aircraft noise has risen by 30 percent since 2014.

“As the airport grows, we need to find creative ways to accept the growth and share the noise,” he said.

OPD is part of a broader $35 billion effort by the FAA called the Next Generation Air Transportation System (NextGen), which involves converting the nation’s airspace from radar-based navigation systems to those guided by satellite.

The improvements have been rolled out in stages, but the overall project has sparked controversy over the amount of time and expense it has incurred.

The new descent protocol was rolled out two years ago at MSP. About 1,100 aircraft arrive daily at MSP, and nearly 80 percent of the planes here are now using the new landing method.

The remaining 20 percent use a different method of descent, usually due to inclement weather.

According to the study released Monday, the airlines have conserved more than 5.8 million gallons of fuel since March 2015, saving about $9.5 million in fuel costs and preventing about 57,000 metric tons of carbon dioxide from entering the atmosphere.

Now, the MAC’s methodology measuring and documenting the environmental benefits will be shared with other airports nationwide.

Cooper, the FAA administrator, called the effort “a monumental environmental accomplishment.”