OMAHA, Neb. (AP) -- The Environmental Protection Agency cleared the way Friday for a higher blend of ethanol to be sold nationwide for the third summer in a row, citing global conflicts that it says are putting pressure on the world's fuel supply.

The agency announced an emergency waiver that will exempt gasoline blended with 15% ethanol from an existing summertime ban. Gasoline with 10% ethanol is already sold nationwide, but the higher blend has been prohibited in the summer because of concerns it could worsen smog during warm weather.

EPA Administrator Michael Regan said the waiver was warranted because of "Russia's unjustified, unprovoked, and unconscionable war against Ukraine" and the ongoing conflict in the Middle East, which he said are putting pressure on the global fuel supply. He said the diminished U.S. refining capacity is also a factor.

The biofuels industry and politicians in the Midwestern states where ethanol is produced from corn praised the EPA's decision. They have portrayed ethanol as a product that helps farmers, reduces prices at the pump and lessens greenhouse gases because the fuel burns more cleanly than gasoline.

"Allowing uninterrupted sales of E15 will help extend gasoline supplies, prevent fuel shortages, protect air quality and reduce carbon emissions," said Renewable Fuels Association President and CEO Geoff Cooper.

Iowa Gov. Kim Reynolds called the decision "a huge victory for Iowa farmers, American energy independence, and consumers."

Environmentalists and others, however, have said increased ethanol production can increase carbon releases because it results in more corn production, leading to increased use of fertilizer and greater releases of nitrate. Synthetic and natural fertilizers also are a leading source of water pollution.

Iowa leads the nation in ethanol production, followed by Nebraska, Illinois, South Dakota, Minnesota and Indiana.

Most gasoline sold across the country today is blended with 10% ethanol, though 15% blends are becoming increasingly common, especially in the Midwest.

The EPA has approved sales of E15 for cars and trucks manufactured after 2000. The RFA estimates that the higher blend will cost consumers more than 25 cents a gallon less than 10% ethanol.

Earlier this year, the EPA permanently approved year-round E15 sales in eight Midwestern states, starting next year. The waiver announced Friday is temporary and only applies this year.