A group of forest scientists, ecologists and climate researchers has sent a strongly worded letter to the U.S. Senate, arguing that a pending bipartisan energy bill amendment introduced by U.S. Sen. Susan Collins incorrectly claims that burning trees for energy is carbon-neutral.

A spokeswoman for Collins defended the amendment, noting that an even larger group of scientists has said they support it.

The letter writers contend the carbon-neutral claim relies on questionable assumptions.

“Legislating scientific facts is never a good idea, but is especially bad when the ‘facts’ are incorrect,” say the researchers, led by Phil Duffy, president of the Woods Hole Research Center. “We urge you and other members of the Senate to reconsider this well-intentioned legislation and eliminate the misrepresentation that forest bioenergy is carbon-neutral.”

The letter is endorsed by 65 forest science researchers and several scientific societies, but others disagree.

“One hundred nationally recognized forest scientists, representing 80 universities, have written to the EPA stating the long-term carbon benefits of forest bioenergy,” said Annie Clark, Collins’ communications director, in a statement sent to the Post. “This group of forestry experts weighed a comprehensive synthesis of the best peer-reviewed science and affirmed the carbon benefits of biomass.”

The amendment, introduced by Maine’s Republican senator with seven bipartisan co-sponsors, states that leaders of the federal government must take actions that “reflect the carbon neutrality of forest bioenergy and recognize biomass as a renewable energy source.”

It is part of a bipartisan energy bill under Senate consideration, and was approved by voice vote this month.

Shortly after its passage, a news release by Collins hailed the amendment, which she said would “help ensure that federal policies for the use of renewable biomass are clear, simple, and reflect the importance of biomass for our energy future.”

The release noted the support of groups including the American Forest and Paper Association and the American Wood Council.

In theory, it makes perfect sense – if you burn wood or wood pellets in a power plant, you generate electricity and carbon dioxide emissions just as you do when you burn, say, coal. The difference is that trees grow back again, and resequester carbon. That sounds carbon-neutral, and such reasoning has fueled a growing biomass-for-energy industry, driven in part by European policies on biomass. But this practice, the letter writers charge, may not be as beneficial for the climate as claimed.

REGROWTH UNPREDICTABLE

One problem, say the scientists, is that it takes a long time for trees to grow back after they’re cut – and a lot can happen in that span of time.

“Wood is burned in minutes and it takes decades to a century or more for it to absorb the carbon dioxide that was released and grow back,” says William Moomaw, one of the letter’s signers and co-director of the Global Development and Environment Institute at Tufts University (Moomaw is also a board member of the Woods Hole Research Center, which released the letter). “All that time carbon dioxide is in the air absorbing radiant heat from the earth and raising the temperature.”

Moomaw adds that the researchers are concerned that “not all trees planted reach maturity because of fire, insects, disease and repurposing of land.” Thus, they fear that they may not be replaced and carbon neutrality may not be achieved.

But Brian Olsen, assistant director of the Ecology & Environmental Sciences Program at the University of Maine in Orono, said in an email to the Press Herald Friday that burning wood to produce energy makes environmental sense.

“Any debate that asks whether or not burning wood is carbon neutral misses the point,” said Olsen, adding that he heats his house with wood. “Burning wood is not perfect, but it is a distinct improvement over fossil fuels, and in regions where forests can be managed sustainably, it can benefit the livelihood and lifestyle of those who harvest it. This isn’t the last step toward achieving a sustainable planet, but it can be the next step.”

This is not the first time this debate has reared its head.

In a letter two years ago, an even larger group of scientists, some of whom signed the current letter, called on the EPA to “rigorously assesses the incremental carbon emissions impacts of bioenergy production.” However, another large group of scientists at the time wrote a letter of their own supporting biomass, arguing, “Most debates regarding the carbon benefits of forest biomass energy are about the timing of the benefits rather than whether they exist.”

AMENDMENT WAS MODIFIED

The current amendment does have strong support from many in the forest community, including the National Alliance of Forest Owners, whose president and CEO, Dave Tenny, told the Post in a statement: “It doesn’t appear that the authors of the letter read the legislation. The amendment clearly states that biomass is renewable and carbon neutral ‘provided the use of forest biomass for energy production does not cause conversion of forests to non-forest use.’ ”

The amendment was modified before passage to qualify the definition of carbon neutrality in this way, something that was highlighted on the Senate floor by Sen. Maria Cantwell, D-Wash., one of the broader energy bill’s chief sponsors. “We agree that some biomass is clearly ‘carbon-neutral’ and some biomass is not ‘carbon-neutral,’ ” Cantwell said.

“We specifically modified the amendment … to ensure we are encouraging forest owners to keep their lands in forests.”