Emissions from wood burning by people in developing countries have a smaller climate impact than previously thought, according to a new study.
“[This] is good news because woody biomass is a fundamental source of accessible and affordable energy for the majority of tropical populations,” said Rudi Drigo, a co-author of the study.
Around the world, 2.8 billion people rely on wood for warmth and cooking. The Intergovernmental Panel on Climate Change (IPCC) estimates that 15 percent of human energy use comes from firewood -- particularly among populations where other forms of energy are inaccessible.
The study looked at the share of wood used for subsistence and the share used for commercial purposes in 90 developing countries and found that wood burning contributes to 2 percent of global climate-changing pollution.
Though wood fuel was believed to be harvested unsustainably, the new study shows that most wood fuel is gathered in a way that allows forests and plots of trees to grow back. About two-thirds of wood for burning is harvested sustainably.
"The original view, that wood fuels are unsustainable, persists and, in some ways, leads to misdirected policies because placing blame on wood fuels prevents people from addressing the actual things driving deforestation and degradation," said Robert Bailis, lead author and professor at Yale University.
Overall, tropical deforestation accounts for about 10 percent of global carbon emissions -- roughly 3 billion tons of carbon dioxide per year. But the majority of tropical deforestation comes from the timber industry and land-use change from agricultural growth rather than from wood burning. Comparatively, 85 percent of global emissions come from fossil fuels, according to the IPCC.
Room to move emissions lower
While emissions from wood burning are not as significant as fossil fuel emissions or other forms of deforestation, there is still room to improve the efficiency of energy from wood. Bailis and his team identified areas where firewood was harvested unsustainably and where emissions were highest. They found that parts of South Asia and East Africa harvested wood faster than it could grow back.
"We hope that our results can support or even promote wood energy planning aiming at increasing sustainable wood fuel production," Bailis said.
The findings could also result in divestments in clean, efficient wood-burning stoves. A number of carbon offset markets pay for better wood stoves as a way to lower emissions. Bailis and his team found these markets are likely paying more for the stoves than they are getting in emissions reductions.
Divestment from clean stoves could present a problem for global health. Every year, more than 4 million people die from indoor air pollution -- and most of this pollution comes from leaky stoves that release smoke inside people's homes.
But Fiona Lambe, a scientist at the Stockholm Environment Institute who did not contribute to the study, is not too worried. She says the study can help carbon offset markets target their work more efficiently.
"In my view, the findings can go a long way in strengthening the environmental integrity of carbon offset cookstove projects," she said. "The study provides accurate, disaggregated data on wood fuel supply and demand which was missing before -- it fills a significant gap. Hopefully this study will be used to strengthen the methods for measuring the climate impact of these projects."