Global — “As of 2007, the shrinking forests in the tropical regions were releasing 2.2 billion tons of carbon per year,” says Lester R. Brown, President of the Earth Policy Institute, in a recent release,“Planting Trees and Managing Soils to Sequester Carbon.” “Meanwhile, expanding forests in the temperate regions were absorbing 0.7 billion tons of carbon annually. On balance, a net of some 1.5 billion tons of carbon were being released into the atmosphere each year, contributing to global warming.”
The tropical deforestation in Asia is driven primarily by the fast-growing demand for timber. In Latin America, its the growing demand for soybeans and beef that is deforesting the Amazon. In Africa, it is mostly the gathering of fuelwood and the clearing of new land for agriculture as existing cropland is degraded and abandoned. Today, because the earths forests are shrinking, they are a major source of CO2. The goal is to expand the earths tree cover, growing more trees to soak up CO2.
Environmental reasons have pushed Thailand, the Philippines, and China to implement complete or partial bans on logging. All three bans were imposed following devastating floods and mudslides resulting from the loss of forest cover. After nonstop flooding in the Yangtze River basin, Beijing noted that it simply did not make economic sense to continue deforesting. The flood control service of trees standing, they said, was three times as valuable as the timber from trees cut. With this in mind, Beijing took the step of paying loggers to become tree planters.
Other countries cutting down large areas of trees will also face the environmental effects of deforestation. If Brazils Amazon rainforest continues to shrink, it may also continue to dry out, becoming vulnerable to fire. If the rainforest disappears, it would be replaced largely by desert and scrub forestland. A burning Amazon would release billions of tons of carbon into the atmosphere, accelerating global warming.
Against this backdrop of growing concern about the forest-climate relationship, a leading Swedish energy firm, Vattenfall, has examined the large-scale potential for foresting wasteland to sequester carbon dioxide. They note that there are 1.86 billion hectares of degraded land in the world and that 930 million hectares of this have a chance of being profitably reclaimed. Some 840 million hectares of this total are in the tropical regions, where reclamation would mean much higher rates of carbon sequestration.
Vattenfall estimates that the maximum technical potential of these 930 million hectares is to absorb roughly 21.6 billion tons of CO2 per year. If, as part of a global climate stabilization strategy, carbon sequestration were valued at $210 per ton of carbon, the company believes that 18 percent of this technical potential could be realized. If so, this would mean planting 171 million hectares of land to trees. This arealarger than that planted to grain in Indiawould sequester 3.5 billion tons of CO2 per year. The total cost of sequestering carbon at $210 per ton would be $200 billion. Spread over a decade, this would mean investing $20 billion a year to give climate stabilization a large and potentially decisive boost.
A number of agricultural practices can also increase the carbon stored as organic matter in soils. Farming practices that reduce soil erosion and raise cropland productivity usually also lead to higher carbon content in the soil. Among these are shifting from conventional tillage to minimum-till and no-till, the more extensive use of cover crops, the return of all livestock and poultry manure to the land, expansion of irrigated area, a return to more mixed crop-livestock farming, and the forestation of marginal farmlands.