Loss of forests contributes as much as 30 percent of global greenhouse gas emissions each rivaling emissions from the global transportation sector. The Kyoto Protocol's offset mechanisms allow credits to be given for replanting trees or establishing new forests, which capture carbon dioxide through photosynthesis. But the current policy regimen does nothing to prevent existing forests from being cut down in the first place.

With Kyoto set to expire in 2012, a new round of talks is under way to develop the next framework for climate change. Experts believe a policy to avoid further deforestation will be a major topic at the conference. But some environmentalists remain wary of forestry climate policy, fearing it will draw attention away from the need to reduce emissions caused by fossil fuels.

The world currently has about ten billion acres of forest. According to the UN Food and Agriculture Organization's (FAO) 2007 report on the world's forests, the world lost about 3 percent of forest area between 1990 and 2005, and the net rate of loss has declined since 2000 (the world loses on average 32 million acres per year). Growth in northern hemisphere forest has helped offset tropical deforestation. There is disagreement, however, on the extent to which increases in temperate-zone forests offset the loss of carbon sinking in tropical zones.

Deforestation is caused by exploitation of natural resources, including expanding populations, logging, agriculture, biofuel production, and wildfires. Clearing forests for the production of biofuels is causing major concern, as experts contend that it has a significant negative impact on forests without doing much to reduce greenhouse gas emissions.

The FAO report shows that the greatest overall loss is occurring in Africa, followed closely by Latin America and the Caribbean. Indonesia has the fastest deforestation rate of any single country in the world. When emissions from loss of forests are taken into account, Indonesia could be considered the world's third-largest emitter of greenhouse gases, according to a recent World Bank report. Indonesia recently has made a show of planting 80 million trees ahead of the Bali conference, but some question the country's long-term commitment to slowing exploitation of its valuable resources, such as stemming illegal logging.

China's rapid growth in the production of manufactured goods that need wood also poses challenges. The country's consumption of forest products leads the world. According to Forest Trends, a nonprofit research group, China's increasing demand has lead to unsustainable and sometimes illegal logging practices in many of the countries seeing significant deforesting activities, such as Indonesia and Papua New Guinea.

China has a seemingly limitless appetite for cheap wood, says Don J. Melnick, a conservation biology professor at Columbia University. Products made from this timber often wind up in U.S. and European markets. Richard Z. Donovan, chief of forestry for the Rainforest Alliance, an advocacy group, says that right now China is not only adding to climate change by burning large amounts of fossil fuels that emit greenhouse gas but also by being a non-discriminating buyer of wood.