This post is a part of a series on Ask a Scientist
Ask a Scientist – September 2012
D. Ramsey from New York, NY, asks “I know that deforestation is causing us to lose valuable carbon-dioxide absorbing forestland globally at an alarming rate. But I rarely hear about reforestation as a means to confront climate change. Does it offer too little hope for making a dent in the problem? Or might a large-scale reforestation effort in the United States or elsewhere make a significant difference?” and is answered by Director of Climate Research and Analysis Doug Boucher.
Reforestation does offer a great deal of promise for confronting climate change, but more so in the long run. Perhaps the biggest difficulty with reforestation as a strategy is simply that it takes so much time to reap the benefits for global warming. If you plant a seedling today, it will take several decades to get the same carbon sequestration benefits we get from mature trees in tropical forests. So, in the short and medium term, reforestation cannot offer nearly as much benefit as limiting deforestation in the first place.
Still, it is important to note that it is a viable strategy. For more background, you should look at a report UCS wrote on the topic called “The Plus Side” (pdf). It is also important to note that, globally speaking, the land is technically available for reforestation on a large scale. For instance, Richard Houghton, a leading expert on the subject at the Woods Hole Research Center, recently estimated that we could make a very significant impact on global warming a few decades from now by planting trees on around 500 million acres. It surely sounds like a lot of land but, by way of comparison, the world has about 10 times that amount in pasture land right now, so it would not be a matter of trying to plant trees in the desert or on lands already used for crop production.
Perhaps the most important thing to bear in mind, however, is that the planet continues to lose some 25 million acres to deforestation each year—a very large amount of forest land, the loss of which results in a major contribution to global warming, not to mention the loss of biodiversity and “ecosystem services” that forests provide, such as helping to supply clean water. In the short or medium run we simply can’t replace that through reforestation. So, over the next decade or more, we have to reduce deforestation and this is where we have been focusing most of our efforts.
The good news is that we now think we can reduce net deforestation to zero over the next several years and we have made a lot of progress to reduce the rate of deforestation already. It’s a very ambitious goal but we think it is a feasible one. In particular, we are heartened by the case of Brazil, where they have managed to reduce the rate of deforestation by more than two-thirds over the past six years. The Brazilian case shows us how much is possible, as do similar success stories in several other smaller countries, such as Vietnam and Gambia.
In our efforts to reduce deforestation, most of our recent work has focused on the key drivers of deforestation today, namely: soybeans, beef, palm oil, and timber. In virtually all of these cases, there are alternative ways for producing these things more productively on land that doesn’t require deforestation. Soybean production, for instance, used to be responsible for some 20-25 percent of all deforestation in Brazil as forests were cut down to make room for its cultivation. Since 2006, however, with a moratorium in place prohibiting the sale or export of soybeans from any deforested area, soy’s contribution to Brazilian deforestation is down to less than two percent of the problem. This can be accomplished elsewhere as well.
Reducing deforestation to make way for beef production is harder, in part because many ranches don’t have clear, legally recognized boundaries. We don’t have the data yet to know for sure whether it has had the same success as with soy, but we think that the cattle moratorium in Brazil since 2006 has the prospect for similar improvements as with soy, by putting pressures in place not to produce or export meat from deforested areas.
Meanwhile, palm oil offers a somewhat different case because just two countries—Indonesia and Malaysia—are primarily involved in its production and the palm oil industry is very productive and profitable, which makes it hard to counter. Plus, palm oil is used in literally thousands of products, from shampoos and cosmetics, to processed foods and even industrial applications. The key here comes in trying to ensure that palm oil is produced sustainably. It is possible to do, in that if you plant oil palm trees in the right places, such as on already cleared or abandoned land, its cultivation can actually yield a net increase in carbon sequestration. But, unfortunately there is more work to be done to stop the ongoing deforestation to make way for lucrative palm oil production which is very bad for the planet and for global warming.
Finally, our latest research on wood products shows that there really is a viable alternative to deforestation by establishing sustainable plantations for wood products, especially multi-species plantations. What turns out to be critical is what kind of land you establish the plantations on. Again, this is a kind of reforestation that can offer a modest benefit in carbon sequestration and a more important one in taking pressure off of existing natural, native forests. But it has to be done on the right lands; when forests are cleared to put in plantations, the net effect is very bad for both the climate and for biodiversity.
So, in all these ways, reforestation does hold real promise for confronting global warming, even though job one remains reducing deforestation now. Most people feel good about planting a tree—and they should—but those efforts can’t replace our overriding need to work to protect the forests that are already there and prevent them from being destroyed.
As UCS Director of Climate Research and Analysis, Doug Boucher coordinates the work of scientists, economists, and other analysts in the Climate and Energy Program. The Tropical Forest and Climate Initiative, which he directs, works with governments, businesses, and consumers to reduce tropical deforestation and the global warming pollution associated with land use.Dr. Boucher earned a B.A. in ecology and history from Yale University and a Ph.D. in ecology and evolutionary biology from the University of Michigan.
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