The Environmental Protection Agency is mandating cuts in the nation’s greenhouse gas emissions. But dozens of environmental scientists from Princeton to Baton Rouge to Berkeley warned last month that the way the agency is writing the rules threatens to sharply increase forest clearing, undermining the EPA effort. The culprit is a familiar obstacle to good policymaking in Washington: bioenergy.

The EPA program is supposed to force power generators to cut back on fossil fuel burning and increase electricity production from cleaner sources of energy. A crucial question, then, is how much credit to give to various alternative energy sources. Replacing coal with solar, wind, nuclear, geothermal and other low-emissions technologies eliminates practically all of coal’s massive carbon footprint, so energy companies that invest in those sources should get a lot of credit.

But the EPA is still figuring out how to count electricity produced by burning wood and other forest products in power plant boilers, an energy source euphemistically called “biomass.” At the moment the agency seems off-track. In a letter to the EPA, the scientists warned Administrator Gina McCarthy that the stakes are very high: Giving biomass too much credit would encourage a lot of wood burning. This is counterproductive, since live trees pull carbon dioxide out of the atmosphere. The scientists found that obtaining a mere 4 percent of the country’s electricity from wood — a realistic outcome if the rules aren’t well-written, according to the U.S. Energy Information Administration — would require burning 70 percent of today’s total timber harvest annually. Other timber would still be needed for construction and paper products.

It’s not enough to demand that landowners selling wood to power companies keep forests about the same as before, because sections of forest harvested for electricity production would have otherwise kept growing, sequestering more carbon dioxide as they grew. Replanting forests would help, but only after decades of regrowth, which is hardly a positive outcome. It’s also not enough to account for how bioenergy policy affects land use in one region or even one country; the EPA also must consider how using land to grow bioenergy products in one place affects how people use land for food, fuel and recreation elsewhere.

It might be that, absent an opportunity to sell timber for fuel, some landowners might uproot their forests and put the land to even less environmentally sound use. But the way to promote forest conservation is to give landowners who preserve their natural resources credit for doing so, not by pretending biomass is cleaner than it is.

Fortunately, the EPA has until the summer to get these rules right.

Editorial by The Washington Post