A few related points
Deforestation and forest degradation are key causes of climate change, responsible for about 15 percent of global warming pollution worldwide. The reason is simply that trees contain enormous amounts of carbon—it makes up about 50 percent of the weight of the wood.
The drivers of deforestation vary a great deal between continents: cattle and soy are important only in Latin America, while palm oil plantations are found almost exclusively in Indonesia and Malaysia.
Diet & Deforestation
Averaged over a whole population, people tend to consume from somewhat below 2,000 to above 3,500 calories per day (Gerbens-leenes, nonhebel, and Krol 2010). While global population has repeatedly doubled in the last few centuries, per capita consumption probably never has, even once. But what has changed a great deal is what kind of food people eat (Galloway et al. 2007). This has important implications for land use and deforestation.
With increasing affluence, people tend to consume foods higher in the food web. They eat more animal products—beef, chicken, pork, eggs, and milk —so the transformation of food plants into edible calories goes through two steps, not one. Plants convert sunlight into food by photosynthesis. Then animals eat those plants, in the process creating meat, but losing a lot of the original stored energy of the plants
Although estimates on how inefficient it is to eat animal products vary depending on the type of animal and how it is calculated, all estimates agree that it is high.
- Wirsenius, hedenus, and mohlin (2010) estimate the food/feedstock conversion efficiency (amount of edible food produced relative to total plant production) for eating cereal grains at 78 percent and for other vegetable products at 60 percent, but just 20 percent for poultry, 18 percent for pork, 15 percent for dairy products, 13 percent for eggs, and a mere 2 percent for beef.
- Gerbens-leenes and nonhebel (2002) calculate the amount of land in europe needed per year (in square meters) to produce a kilogram of edible food as 0.3 for vegetables, 0.5 for fruits, 0.5 for beer, and 1.4 for cereals, compared with 1.2 for milk, 3.5 for eggs, 7.3 for chicken, 8.9 for pork, 10.2 for cheese, and 20.9 for beef.
Pasture expansion to produce beef cattle is the main agent of deforestation in Brazil, occupying more than three-quarters of the deforested area. Beef production in the amazon tends to be extensive, with low levels of meat production per unit area.
Although most people think of soy in terms of traditional East Asian foods like soy sauce, soy milk, tofu, tempeh, and similar dishes, most soybeans are not consumed by people, but by livestock. Chickens, pigs, and cattle eat most of the global soy crop.
With the growth of meat consumption and the collapse of the peruvian anchovy fishery (previously an important source of fish meal for livestock feed) the world demand for alternate sources of protein meal to feed livestock made soy a profitable crop in the global market.
In the late 1990s, using new, humid-tropic-adapted varieties, soybean cultivation began to enter the amazon forest in earnest, growing by 15 percent a year for several years (Nepstad, stickler, and almeida 2006). Large farms were cut out of forested areas, often using heavy machinery such as bulldozers for rapid clearing, and soybeans were put into production with substantial amounts of fertilizers and pesticides.
There is hope
In recent years, there has been a considerable decline in tropical deforestation.
The clearest such “success story” is in the largest tropical forest country, Brazil. Pressure from civil society led to an industry moratorium on buying soybeans from deforested areas beginning in 2006, and recent data indicate that soy’s role as an agent of deforestation has diminished greatly as a result. As with soy, civil society pressure in Brazil has led to a moratorium since 2009 on buying beef from ranches that have cleared forests to create pasture.
Pasture expansion remains an important driver of deforestation in Colombia and other Latin american countries, although over much smaller areas than in Brazil.
Reducing growth in the demand for commodities that drive deforestation will be important to future successes.