WASHINGTON — Scott Pruitt’s Environmental Protection Agency said Monday that the burning of biomass, such as trees, for energy in many cases will be considered “carbon neutral” by the agency.

“Today’s announcement grants America’s foresters much-needed certainty and clarity with respect to the carbon neutrality of forest biomass,” Pruitt said at an event with forest industry leaders in Georgia.

But the consideration of biomass as carbon neutral is contentious among scientists, who fear that forests, once cleared so that their wood can be used for energy, may not grow back as planned.

“The big problem is you’re cutting old growth forests and expecting them to regrow,” said William Schlesinger, president emeritus of the Cary Institute for Ecosystem Studies and an EPA Science Advisory Board member. “That’s totally unrealistic in 20 years and not guaranteed over 100 years.”

[Opinion: Why Collins deserves praise for fighting for Maine’s biomass industry]

The contention that burning wood for energy is carbon neutral rests on the idea that trees pull carbon out of the air as they grow. Therefore, while burning trees releases carbon dioxide emissions into the air, carbon will be pulled out again if the trees grow back. This suggests that burning trees, or wood chips, for energy can be considered a renewable and sustainable energy source.

But it quickly gets more complicated, which is why the carbon neutrality of biomass has been so hotly debated by some scientists. The EPA’s Science Advisory Board had not completed deliberations on the matter, and the agency’s policy memo released Monday acknowledged that the board had determined in 2012 that “it is not scientifically valid to assume that all biogenic feedstocks are carbon neutral,” but rather that any such determination requires further analysis.

One is that, while carbon dioxide emissions from the burning of wood go into the air immediately, trees take decades or more to grow back. So if anything happens to interfere with their growth, such as changes made by forest owners based on economics or other factors, the emissions might not actually be “removed” from the air again.

Yet another consideration arises if wood products are shipped long distances before being burned — for instance, to Europe, which burns a great deal of wood for energy. The energy used for shipping adds to the total greenhouse gas emissions of the entire process.

Schlesinger said Pruitt has undercut the board — which had been “divided on this subject,” he said — by making this decision. “There would be no point in doing it now,” he said. “We’re supposed to provide analysis of the basis of decisions. He’s already made the decision. So what’s our role?”

Some forest scientists, however, support the idea that biomass is carbon neutral. More than 100 of them signed a letter to the EPA in 2016 to make that case.

[Opinion: We can’t unquestionably champion biomass as clean, healthy energy]

The forest products industry and private-forest holders celebrated the EPA announcement. The designation of wood-burning energy as carbon neutral could make it easier for the industry to compete with fossil fuels and bolster their calls for deregulating biomass carbon dioxide emissions so that they are not subject to some provisions in the Clean Air Act.

“Recognizing that forest biomass in the U.S. provides a carbon-neutral source of renewable energy will encourage landowners to replant trees to keep our forests healthy and intact and provide good-paying jobs well into the future,” Dave Tenny, the founding chief executive of the National Alliance of Forest Owners, said in a statement.

Should a new administration revive former President Barack Obama’s Clean Power Plan, or something like it to curb carbon emissions, this new policy means wood energy would be treated like solar and wind power — since in the EPA’s eyes all three are zero-carbon sources of electricity.

Across the Atlantic, European countries are trying to curb carbon emissions to meet promises made under the Paris climate accord, unlike the United States under President Donald Trump. But even there, European Union policymakers have already declared wood energy carbon neutral. The loophole has led to a flourishing trade by which North American trees are chopped down, compressed into pellets and shipped to Europe to be burned.

Congress, too, has sided with industry. On Monday, the EPA said it was spurred by the May 2017 spending deal that mandated that the agency, along with the Departments of Energy and Agriculture, make sure their policies “reflect the carbon-neutrality of forest biomass.”

Still, Sami Yassa, a scientist with the environmental nonprofit Natural Resources Defense Council, said the EPA’s announcement Monday is in line with many of the other pro-industry stances Pruitt has taken.

“Once again,” Yassa said, “here he’s dismissing established science to give a free pass to his industry pals to pollute.”

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