Comment & Debate
Reforestation is the restocking of existing forests and woodlands which have been depleted, with native tree stock. The term reforestation can also refer to afforestation, the process of restoring and recreating areas of woodlands or forest that once existed but were deforested or otherwise removed or destroyed at some point in the past. The resulting forest can provide both ecosystem and resource benefits and has the potential to become a major carbon sink. The concept of forests as carbon sinks has drawn attention around reforestation as a possible tool in the fight against global climate change. Because trees draw carbon dioxide from the atmosphere in the process of photosynthesis, they can potentially remove this excess greenhouse gas from the atmosphere and help fight global warming. The main question in this public debate is whether reforestation should be emphasized in strategies to combat global warming. Subsequent questions include whether it can have a significant effect in reducing atmospheric greenhouse gases and offsetting current emissions. Can reforestation have an immediate, medium-term, and long-term impact in reducing emissions? Does reforestation have the effect of releasing methane gas upon the decomposition of forests? Is reforestation a competitive approach to combating global warming compared to the alternatives? Is there enough land for major global reforestation projects? Should this approach be emphasized in plans to combat global warming?
“According to a neat calculator on the Web site of Casey Trees, a fair-size white oak tree with an 18-inch-diameter trunk would reduce atmospheric carbon dioxide by 622 pounds per year. A mature apple tree would lower carbon dioxide by more than 300 pounds. Even the weedy tree of heaven would store (“sequester,” in eco parlance) 391 pounds once it reached a trunk diameter of 12 inches.
Reforestation leads to the immediate growth of trees, and, therefore, the immediate reduction of greenhouse gases. “Carbon sinks won’t solve global warming”. Planet Ark. 9 Jul. 2001 – “The primary benefit of land carbon sinks is that they can be effective immediately.”
American Forests executive director, Deborah Gangloff – “We aren’t going to solve global warming by planting trees, but we can take up a lot of carbon.”[2]
“The plan to use trees as a way to suck up and store the extra carbon dioxide emitted into Earth’s atmosphere to combat global warming isn’t such a hot idea, new research indicates…Scientists at Duke University bathed plots of North Carolina pine trees in extra carbon dioxide every day for 10 years and found that while the trees grew more tissue, only the trees that received the most water and nutrients stored enough carbon dioxide to offset the effects of global warming.”
“The scientists [of Britain’s Royal Society] also warned that in the future carbon sinks could become a source of CO2. They could release greenhouse gases, such as methane.”
“One researcher [of a Duke University Study] noted, ‘If water availability decreases at the same time that carbon dioxide increases, then we might not have a net gain in carbon sequestration.’ Well, climate change is projected to decrease water availability in many parts of the world, including the American West. If water availability decreases at the same time that carbon dioxide increases, then we might not have a net gain in carbon sequestration.”
“Trees only absorb large quantities of carbon during their growth, so once they are fully grown–in other words, when the reforestation is complete–they will not be able to serve as CO2 sinks.”
Forests are dark and absorb significant sun energy (increasing albedo), trapping heat that would otherwise be reflected by lighter-colored surfaces such as ice. Reforestation, therefore, can worsen global warming.
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