When it comes to the growing threat of climate change, the shrinking rainforests of South America get a lot of attention. But one Boston-area scientist says we should also be looking closer to home.

"One could almost say that getting people to focus on the Amazon is a bit of a distraction so we can cut down our own forests," said Bill Moomaw, an emeritus professor of international environmental policy at Tufts University.

Ina new paper in the journal "Frontiers in Forests and Global Change," Moomaw argues that here in the U.S., and specifically in New England, the practice of “sustainable forestry” is not sustainable for the climate.

"You ask a forester when is a tree ready to be cut down, and he'll say it's when it's between about 9 and 11 inches in diameter," Moomaw said. "For a lot of our species, that's somewhere around 75 years, which is why the median age of trees in the northeast is 75 years. They've been kept small."

As part of its sustainable forestry practices, Massachusetts generally follows this guideline on state land, Moomaw said, as well as in privately-owned forests that are managed through a state stewardship program. If the goal is removing more carbon from the atmosphere, Moomaw says that’s exactly the wrong time to cut down trees.

"Seventy-five years for many species is when they really start to take off on their fastest growing spurt," he said. "And 'fastest growing' means they're sucking carbon out of the atmosphere and converting it into wood fiber. Half of the mass of wood fiber is carbon."

In the paper, Moomaw argues that if current management practices continue, the world's forests will only achieve half of their carbon sequestration potential, and the expected consequences of climate change are so disastrous that this must be taken into account when deciding which trees to cut down.

"This doesn't mean we never cut trees for timber production," he said. "What we need to do is decide which forests — the ones that are going to be growing rapidly in the next 50 to 100 years — do we set aside for climate protection, and therefore which other forests would we allow some amount of cutting for wood products?"

Foresters say they're balancing a number of goals as they figure out how best to manage a forest.

"Your goals might be to increase the value of the standing timber on the property," said Chris Egan, executive director of the Massachusetts Forest Alliance, a trade association representing forest landowners, foresters, timber harvesters and forest product companies in the state. "It might be to increase wildlife habitat. It might be to grow big trees."

And meeting each of those goals requires a different strategy, he said, some of which include harvesting trees.

"Trees compete for resources," he said. "So when when a forester does a thinning — they come and remove some trees across a certain area — that will actually speed up the growth of the remaining trees, because they have more access now to sunlight. They have more access to soil nutrients and water."

Egan also said that people need products that come from forests.

"From our homes made of wood, hardwood floors, wood furniture to our books our magazines and newspapers, to toilet paper and things of that nature ... and they need to come from somewhere," he said. "And if we can remove them sustainably from the forest, keeping it healthy, keeping it growing, that's a benefit."

As for the climate impact of cutting older trees, Egan argues the science is still very unsettled.

"The carbon accounting for wood is extremely complex," he said. "We're learning more about it every day, and we're still early in the process of of figuring these things out. ... Different studies are saying different things, and we're trying to examine those and come to a better understanding of those carbon dynamics."

State officials also defend their forestry practices.

“The commonwealth is proud of its creative and aggressive approach to reduce greenhouse gas emissions, and continues to implement selective forest management projects in an effort to promote the health of woodlands and diverse habitat across the state, and increase forest resilience to climate change impacts,” said Troy Wall, a spokesman for the state Department of Conservation and Recreation (DCR), which is responsible for state forests and for managing a stewardship program for private forests.

Officials say the vetting process for timber harvest projects is extensive — projects are reviewed by wildlife experts, state ecologists and park operations staff, and an archaeologist who weighs in on any relevant cultural resources. That's followed by a public comment period, public meeting and a public tour of the project's location.

But for conservation activists like Michael Kellett, the state's forestry policy is a relic of a bygone era.

"Not one acre of state land has permanent legal protection from being logged or or even having pipelines and stuff built across them," said Kellett, executive director of the nonprofit conservation organization Restore the North Woods. "People think our forests are protected, but they're really not permanently protected."

Kellett said the state forestry laws were written in the 1940s, when wood was needed for World War II.

But times have changed, Kellett says, and other priorities need to take precedence.

"This is the era of climate change, of mass extinction danger across the world," he said. "We've got twice as many people and less space for green space for people. Why are we logging these lands?"

Kellett and his organization are currently fighting a plan to harvest trees in Wendell State Forest in Millers Falls, near the intersection of Massachusetts, Vermont and New Hampshire.

"They're purely doing it because these trees are valuable and they're at the age where they can sell them," he said. "And that's the problem, our current law, their mandate is to — quote, manage, unquote — the forests, including producing wood supply."

The state DCR says that's not the goal behind its plan for Wendell State Forest, which addresses three forested areas. One is an area of a non-native red pine trees, which the department wants to replace with a more native species. The DCR also plans to replace a section of oak trees with a multi-species forest that's more resilient to pests. And they'd like to turn a white pine area into a "young forest" habitat that's critical for wildlife species like the whip-poor-will.

The dispute over Wendell State Forest has led to the introduction of new state legislation that would prohibit logging on 650,000 acres of state land.

The bill, which was introduced this session by Rep. Susannah Whipps of Athol, would prohibit timber on lands owned or under the care of the DCR from being sold, removed, or destroyed. It also would ensure that those properties can't be leased, sold, or exchanged to any corporation and prohibits building pipelines, solar arrays or other energy resources on that land. The bill was referred to the House committee on Environment, Natural Resources and Agriculture in January.