For many years, small farmers in developing countries have been blamed for deforestation because of the way that they make breakfast. While in developed countries nearly everyone cooks with fossil fuels, or with electricity generated by fossil fuels or hydroelectricity, in developing countries firewood still predominates, especially among the poorest people in rural areas. But is this really an important driver of deforestation—and thus a major contributor to global warming? A new study—the most in-depth and comprehensive look at the subject yet—says no.
If you just look at the global numbers related to “traditional woodfuel” use, most of which is in tropical countries and is for cooking, not for heating, they seem quite large. Global woodfuel demand is over 1.3 billion tons. It accounts for over half of global wood harvest and nearly 10 percent of the total primary energy used worldwide. Nearly 3 billion people worldwide not only use wood for fuel, but have no real alternative. Although often left out of global discussions of bioenergy and biofuels —excluding it from consideration by adding an adjective like “non-traditional”—this firewood is by far the largest use of bioenergy on the planet.
The results indicate that the fraction of woodfuel biomass that is unsustainably harvested is between 8 and 30 percent, depending on the assumptions and scenarios chosen. The woodfuel “hotspots,” where more than half of the wood harvest is unsustainable, amount to just 4 percent of the tropics, inhabited by 6 percent of the tropical population. The global warming pollution associated with unsustainable woodfuel use amounts to 1.9-2.3% of total global emissions. This is not negligible—it amounts to about a billion tons of carbon dioxide—but it’s considerably less than previous, less sophisticated analyses have estimated.
The results of Bailis et al. confirm, and go well beyond, the point that my colleague Calen May-Tobin made in 2011 in the “Wood as Fuel” chapter of our book on the drivers of tropical deforestation, Root of the Problem. He argued that the published literature did not justify the assertion, based on large numbers like the ones I quoted above, that woodfuel was a major driver of deforestation and global warming, because that assertion erroneously assumed that all firewood collection came from natural forests and caused deforestation. Bailis and colleagues have now done a much more detailed analysis, and come to the same fundamental conclusion.
In fact, one additional point may reduce even more the degree to which small farmers are responsible for global warming pollution. As one sees in going out firewood collecting with villagers in tropical rural areas, they seldom cut down mature trees. That wouldn’t make sense, since for the traditional kinds of cooking fires one needs small branches, not big logs. Much of what they gather is small trees, often already dead, or fallen branches.
If this is the case, then firewood collecting is only speeding up the release of carbon dioxide that would happen anyway when those dead trees and fallen branches rotted. Burning oxidizes the carbon in wood rapidly, while rotting does it slowly, but the end result is the same. Thus there are no additional greenhouse gas emissions due to using this wood for cooking fires, and therefore no added impact on global warming. It’s not clear to me whether this issue is fully dealt with by Bailis et al.’s analysis—nor, indeed, whether it can be, with the present limitations of the available data.
I should add that charcoal making is an exception to these patterns, since it often uses large, dense trees which are felled specifically for this purpose. However Bailis et al. estimate that charcoal makes up only a small fraction of traditional woodfuel. Thus, although it can have damaging impacts on forests close to large cities, its impact on global warming is relatively small.
Bailis et al. also estimate the climate benefit of distributing more efficient cookstoves in rural areas, which is often justified and paid for with voluntary carbon market credits, based on its supposed climate benefit. Not surprisingly, they find that this benefit has been overestimated. This makes the public health importance of better cookstoves—they reduce the emissions of black carbon and other substances that do great damage to the health of the women who cook meals using traditional fires—even more important. The point is not to stop efforts to improve cookstoves, but rather to do it to protect the health of the world’s poorest rather than the health of our atmosphere.
I’ve only scratched the surface of this important new research, which in both the sophistication of its analysis and the amount of data utilized goes far beyond previous work. Bailis et al.’s voluminous data—the supplementary material for their paper goes on for more than a hundred pages—is likely to be an important resource for other researchers for years to come. But they have already made a vital contribution, in showing how we’ve overestimated the global warming responsibility of developing country farmers cooking their families’ food.
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