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Loss of tropical forests accelerated roughly 60 percent during the 2000s, argues a paper published in the journal Geophysical Research Letters. The findings contradict previous research suggesting that deforestation slowed since the 1990s.
The study is based on a map of 1990 forest cover developed last year by Do-Hyung Kim and colleagues from the University of Maryland. The map, which includes 34 countries that contain 80 percent of the world’s tropical forests, enabled the researchers to establish a consistent baseline for tracking forest cover change across regions and countries over time.
The study concludes that average annual gross forest loss in the tropics rose 58 percent in the 2000s relative to the 1990s rate. Overall 78.2 million hectares of forests were lost during the decade, up from 49.3 million.
Accounting for forest regeneration, afforestation, and establishment of plantations, net tree cover loss amounted to 65.4 million hectares or 62 percent above the 40.4 million hectares lost in the 1990s.
The large increase in forest loss reported in the study contrasts sharply with data from the U.N. Food and Agriculture Organization (FAO), which estimated that tropical forest loss declined by about a third in the 2000s. While its data has often been criticized, until recently the FAO has be considered the standard-bearer for measuring forest cover change on a global basis. FAO uses a combination of self-reported government data, surveys, and remote sensing to develop its estimates, whereas the new map is based on automated analysis of Landsat satellite imagery. Accordingly, much of the discrepancy between the two data sets results from countries where FAO reported “no data” or “no change” in forest loss rates.
Still there were some notable differences between the two. For example, FAO shows forest loss in Indonesia declining from 1.914 million hectares a year in the 1990s to 497,500 hectares a year in the 2000s, a drop of 74 percent. But the new study reports a 29 percent increase, from 653,000 ha to 842,000 hectares.
Generally FAO tended to report higher rates of loss in the 1990s and lower rates of loss in 2000s than the researchers’ approach. Overall FAO estimated forest loss across the 34 countries at 131 million hectares over the 20-year period, whereas the University of Maryland team’s estimate came in at 106 million hectares.
Regionally, the new study found the largest extent of tropical forest loss occurred in Latin America during the 2000s (4M ha/yr), while tropical Africa (251,000 ha/yr to 594,000 ha/yr) experienced the biggest jump — 137 percent — in percentage terms. Average loss in Asia climbed 63 percent between the 1990s and 2000s: 1.2M ha/yr to 2M ha/yr.
Among the countries assessed, Nicaragua lost the largest area of forest cover since 1990: 21.7 percent. It was followed by Cambodia (19.1 percent), Sri Lanka (15.8 percent), Madagascar (15.1 percent), and the Philippines (14.2 percent).
Comparing recent forest loss (2005-2010) to a 1990s baseline, the Democratic Republic Congo experienced the biggest jump its rate of forest loss: 394 percent. It was followed by Venezuela (359 percent), Nicaragua (345 percent), and Bangladesh (283 percent). In contrast the rate of net forest loss fell sharply in Gabon, Liberia, Papua New Guinea, Guyana, and Suriname between the two periods.
While the findings are sobering, they show that forest loss slowed during the second half of the 2000s. That trend has continued past 2010 at least in the Brazilian Amazon — the largest block of tropical forest in the world. Trends outside the Brazilian Amazon are less clear, but another team of University of Maryland researchers will be releasing 2013 data soon.
More broadly, the new data will provide researchers a new baseline for measuring progress in curbing deforestation and associated emissions, which account for around a tenth of carbon dioxide emissions from human activity. Other forest cover data developed by University of Maryland researchers has been integrated in Global Forest Watch, an online platform for tracking the world’s forests, and is now being used widely by policy makers and conservationists as part of a global push to reduce deforestation and forest degradation.
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