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The wood industry is a massive source of uncounted carbon emissions, according to a pioneering study in North Carolina. The same is probably true globally.

In places where trees are replanted after being cut down, the wood industry is often promoted as being sustainable. But no one is counting all the carbon emissions associated with logging because international rules on how this should be done are wildly inadequate, says economist John Talberth at the Center for Sustainable Economy, an environmental think-tank based in Oregon, US.

“The accounting rules were written by loggers for loggers,” he says. “That’s why you hear of agriculture as a big source of emissions, but not logging and wood products.”

Each year 80,000 hectares of trees in North Carolina are cut down to produce wood pellets that are then burnt in power plants in the UK, as well as for paper and timber. The state does not count the resulting emissions. But Talberth has calculated them based on data from the US Department of Agriculture’s Forest Inventory and Analysis Program.

His takes account of factors such as the carbon released as the roots of cut trees rot in the ground and the fertilisers, herbicides and pesticides applied to tree plantations. The conclusion: logging in North Carolina emits 44 million tonnes of carbon dioxide a year.

That makes it the third largest source in the state, just behind electricity generation and transportation, and far ahead of farming and other industries.

Talberth has carried out a study like this before. In 2017, he found that logging was the single biggest source of carbon emissions in Oregon. And an came to the same conclusion in 2018.

But such comprehensive studies have never been done for other states and the rest of the world. If they were, Talberth says logging would turn out to be one of the top three or four sources of carbon emissions globally. The life-cycle approach should be adopted nationally and internationally to provide a full picture of emissions, he says.

The good news is that Talberth’s study also showed that if land owners adopted “climate smart” practices, forests in North Carolina could soak up 3 gigatonnes of CO₂ over two or three decades. That would cancel out 20 years of the state’s carbon emissions.

The main such practice would be to cut trees every 60 or 90 years rather than every 30 years or less. Those cuts should be done in small patches rather than clearcutting vast areas. And foresters should grow a mix of native species rather than monocultures of alien species. Such forests would store more carbon and support more wildlife.

“Climate smart”

While bigger trees are more valuable to loggers because they contain more wood, the transition to longer rotations would cost land-owners in the short-term. But Talberth says the wood industry is subsidised – and these subsidies could be made contingent on adopting climate smart practices.

It is widely assumed that wood is carbon neutral. “This study really underlines that that assumption cannot be taken for granted,” says Duncan Brack at the policy research institute Chatham House in London. Brack wrote a 2017 report on the effects of the massive European Union subsidies for wood burning.