All forests are not equal in the carbon count
To clean up our carbon mess, we don’t just need more forests, we need better forests in the right places
By Joshua Tewksbury | Data Visualization by Nigel Hawtin
Source: World Bank data
1. Forests, shrublands, and even grasslands soak up a lot of carbon. According to a recent study, Earth’s vegetation is soaking up nearly half the carbon it would in the absence of human development. (1) Part of the problem comes from land conversion; humans now have converted an area the size of Africa for agricultural use. The other part comes from degradation of natural, unconverted lands, mostly forests.
2. Forest gains and losses are unevenly distributed around the world. On balance, temperate and boreal forest cover has remained relatively unchanged over the past several decades, even as the agricultural footprint has expanded. In tropical countries, however, within the same time period, an area the size of Austria has been removed each year. Much of this is due to forest clearing for agriculture.
3. And that’s a carbon problem, because two-thirds of current carbon stocks are held in the tropics. Karl-Heinz Erb and his colleagues estimate that tropical forests, if managed to retain 90 percent of their carbon potential, would soak up four to five times more additional carbon than similarly managed temperate forests. Current levels of extraction and degradation in natural landscapes reduce carbon-holding capacities to 60 percent of their potential; outright land conversion to agriculture reduces capacities to 10 percent. (1)
4. However, changes in forests and agriculture are not always linked. Honduras, for example, has lost 43 percent of its forest cover and experienced large-scale degradation of many of its remaining forests within the past 25 years—but not generally due to agricultural expansion. Instead, a mix of weak governance, illegal logging, and rapidly rising narco-deforestation (deforestation linked to illegal drug trade) is likely to blame. (2) In contrast, China has increased both agricultural area and forest cover. It has added forest area the size of Spain through domestic logging restrictions, reforestation, and forest plantation expansion.
1. Erb KH et al. Unexpectedly large impact of forest management and grazing on global vegetation biomass. Nature 2018.
2. McSweeney K et al. Drug policy as conservation policy: Narco-deforestation. Science 2014.
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