New Insights from an Old Routine

Richard Houghton

Acting President & Senior Scientist
Richard A. Houghton

From the earliest days of the Woods Hole Research Center, scientists have been determining the annual global emissions of carbon that result from the management of land. In recent decades the largest emissions have come from tropical deforestation, and the long-term work of WHRC helped provide the basis for an international agreement for reducing those emissions (REDD – Reducing Emissions from Deforestation and forest Degradation). The emissions of carbon from land use were determined with a computer model that calculated the changes in carbon that accompanied any change in land use (for example, deforestation or reforestation). The model was conceptually simple (like balancing a checkbook) but tracked land areas and carbon stocks under different types of management – globally. In accounting for logging and shifting cultivation, as well as changes in agricultural land, the model kept track of regrowing forests.

Because the emphasis had always been on the annual emissions of carbon, we paid little attention to other results that were calculated by the model – until fairly recently, when we asked a different question: how much carbon is taken out of the atmosphere each year as a result of forest growth?  Emissions result from deforestation, not forest growth, so we hadn’t paid much attention to forest growth. But the emissions we were reporting were netemissions, composed of still greater gross emissions to some extent offset by gross uptake of carbon in forests recovering from logging and agricultural abandonment.

Think of it this way. When a forest is logged, the wood products find their way into paper, lumber, houses, National Geographics, etc., none of which lasts forever. Every year there is some burning or decay of these products.  Further, when a forest is logged, there are often branches, roots, stumps, and leaves left behind in the forest. This debris also decays over time, releasing carbon to the atmosphere. Altogether these emissions are the gross emissions. But logging is often following by forest regrowth, which removes carbon from the atmosphere. That removal is a gross uptake of carbon.  Put the gross emissions and the gross uptake together, and you have the net flux of carbon.

So, we knew (the model calculated) the amount of carbon removed from the atmosphere each year as a result of forest growth everywhere on the Earth – or at least forest growth from logging, shifting cultivation, and agricultural abandonment.  And that gross uptake, globally, is 1-3 billion metric tons of carbon per year. If we add that 1-3 billion tons of uptake to the reduced emissions (another billion metric tons if deforestation and degradation were stopped, a number that also comes from the model) and another billion that would be taken out of the atmosphere if millions of degraded lands were reforested, we have the potential to remove 3-5 billion tons of carbon from the atmosphere, annually, just by managing forests.

Forests don’t grow and accumulate carbon forever, but they do grow for tens to hundreds of years. And if the world’s forests were managed to take advantage of this growth, forest management could keep the carbon dioxide concentration from increasing long enough to replace fossil fuels with a new infrastructure of renewables and to implement new efficiencies in energy use. In other words, forest management is not the solution to climate change. Getting off fossil fuels is. But forest management could play a strategic role in the transition. It could keep concentrations of carbon dioxide from increasing during the years we’re reducing fossil fuel use.

And that simple concept (obviously not simple to implement globally) has been noticed.  The United Nations Development Programme is releasing the New York Declaration on Forests later this month, and that Declaration promotes the restoration of degraded landscapes as a means to counter global warming. The Global Commission for the New Climate Economy, whose Programme Director is Jeremy Oppenheim (a WHRC Board member), also points to the use of land and forest management as a means for taking carbon dioxide out of the atmosphere.

The simple concept and the numbers behind it have the potential to result in a new agreement much more powerful and comprehensive than REDD, involving not only tropical countries and not only forests. We have the potential to restore the biosphere, producing more food at the same time we reduce emissions of greenhouse gases. There’s much more at stake than land, carbon and climate, but monitoring, modeling, and understanding those elements is the business of the Woods Hole Research Center.