4 April 2018: Burning Wood in Norway

Today's news brings epic eye-rolling over gender pay gap excuses, Trump’s wall built from the flesh of military personnel, and Russia and Facebook vying for the world’s least-trusted institution.

Instead, ignore the front page and curl up in front of a warm fire while we consider the science of burning wood in Norway, published in the journal Scientific Reports recently. But don’t get too comfy there — this toasty-warm, carbon-neutral energy source may not be quite so climate-friendly after all.

The Norwegians have raised the chopping, stacking and burning of wood to an art form — they even make epic 12-hour TV shows about it. Statistics Norway estimates over a million households burned more than a million tonnes of wood in 2016.

Because the wood is sourced mostly from plantation forests, it’s considered to be a carbon-neutral energy source: the carbon released as the wood burns are absorbed by the next generation of growing trees. CO2 released from burning biomass aren’t even counted in measures of carbon emissions.

Not so fast, say a collaboration of researchers from the Norwegian University of Science and Technology, the Norwegian Institute of Bioeconomy Research, the Norwegian University of Life Sciences and SINTEF Energy. While the cycle of biofuel carbon emission and re-absorption is broadly true, the full impact of burning so much wood on the climate is a bit more complex, and may in fact be warming the planet a lot more than previously thought.

First, there’s the issue of logging. Cutting down and chopping up so many trees requires loads of machinery, which emits a lot of carbon. Then again, the warming caused by those emissions is offset by the cooling effect of the large, snow-covered areas uncovered by logging, which reflect sunlight back into space.

The researchers also measured many different kinds of carbon emissions coming out of Norway’s many chimneys, including soot, also known as black carbon, which has a double impact on climate. Not only does soot itself increase warming in the atmosphere, it settles on snowy ground and reduces reflectivity, decreasing the snow’s cooling effect.

Soot emissions have halved in the last few decades thanks to modern, efficient wood-burning stove technologies. But the size of the soot particles is an important factor in their warming effect, and the tiniest, nano-sized particles are the most challenging to filter out.

So while it’s not necessary to brick up the fireplace, lock away the axe, and binge-watch your scandi-noir dramas under a duvet, this research shows just how tricky it is to be Hygge and carbon neutral at the same time.

Original Paper: Scientific Reports volume 8, Article number: 3299 (2018)

Find it at: www.nature.com/articles/s41598-018-21559-8