In late 2006, former World Bank chief economist Nicholas Stern pointed out in the Stern Review on the Economics of Climate Change that while about two thirds of greenhouse emissions come from fossil fuels like coal and petroleum, the remaining third are the result of agriculture and deforestation, given that forests are the natural world's greatest "carbon sink."
2006 年底由前世界銀行首席經濟學家史登提出的「史登報告」（研究氣候變遷對經濟的衝擊）指出，溫室氣體排放的來源，除了燃燒煤、石油等石化燃料（佔 2/3），另外 1/3 的排放，就來自農業和砍伐森林，因為森林是自然界最大的「吸碳庫」。