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The years 2016 and 2017 were especially bad for the world’s tropical forests as dry, hot weather led to widespread fires that, along with activities like clear-cutting for agriculture, resulted in record levels of forest destruction.
Last year was generally wetter and had fewer fires, so forest loss was expected to be lower. Data released Thursday show that is the case, but there’s little cause for celebration.
In all, about 30 million acres of tropical forest were lost in 2018, according to an analysis of satellite images released by Global Forest Watch, a program of the environmental research group World Resources Institute. This is down from the highs of 42 million acres in 2016 and 39 million acres in 2017.
But the 2018 total is still the fourth highest since satellite analysis began in 2001. “If you look back over the last 18 years, it’s clear that the overall trend is still upwards,” said Frances Seymour, a fellow at the institute. “We’re nowhere near winning this battle.”
Of the 2018 total, close to nine million acres (an area the size of Belgium), were old-growth, or primary, forest, which stores more carbon than other types of forests and provides habitat that is critical to maintaining biodiversity. The nine-million-acre total is the third highest since 2001.
There was some good news in the data. Indonesia, which in 2016 instituted new conservation policies following devastating fires, had less forest loss for the second year in a row.
“It seems that Indonesia’s forest policies are working,” said Mikaela Weisse, manager of the Global Forest Watch program. But the country will face a new test this year, Ms. Weisse said, as El Niño conditions may bring more warmth and dryness, increasing the risk of forest fires.
But Indonesia’s progress was more than offset by increases in forest loss elsewhere, including some African countries. Loss is becoming more decentralized, Ms. Weisse said. Where 15 years ago Indonesia and Brazil accounted for nearly three-quarters of forest loss worldwide, this year they account for less than half.
Forests, both in tropical and more temperate regions, play an important role in combating climate change, and estimates are that they are declining in size overall. A United Nations study, for example, found that worldwide forest coverage declined by about 3 percent between 1990 and 2015.
Forest health is linked to climate in two ways. Through photosynthesis, trees and other vegetation remove about one-quarter of the carbon dioxide emitted by human activities, so fewer trees mean more CO₂ remains in the atmosphere. Dead trees also add greenhouse gases to the atmosphere, releasing them when they are burned or decompose.
The Global Forestry Watch data is compiled by researchers at the University of Maryland who have developed software that analyzes forest canopy cover using Landsat photographs. The analysis cannot differentiate between losses from natural events like hurricanes and those resulting from human activities like clear-cutting for logging, agriculture or mining. (Fires are often set during clear-cutting operations, but in hot, dry weather can burn out of control, causing more extensive destruction.)
Brazil still loses the most tree cover each year, by far. While its 2018 total old-growth loss of about 3.3 million acres is lower than the fire-fueled numbers of the previous two years, it was higher than any other year since 2005, when the country was successfully reducing its loss rate.
The country’s new far-right leader, Jair Bolsonaro, who took office in January, has pledged to open more protected land to mining, agriculture and other development, so Brazil may be poised for more forest loss in coming years.
Ghana and Ivory Coast had the largest percentage increases in forest loss, in part because of increased clear-cutting by cocoa farmers expanding their plantations in response to worldwide demand for chocolate. In Madagascar, agriculture and mining resulted in the destruction of 2 percent of the country’s old-growth forests last year, the highest proportion of loss of any country.
In the Amazon basin, Colombia had increased loss for the second year in a row, the lingering effect of a peace agreement between the government and a rebel group that opened land previously held by the rebels to private development. On the other side of the Amazon, in Bolivia, clearing for large-scale agriculture and pasture contributed to increasing forest loss, the institute said.
Ms. Seymour said the experience of Indonesia, where the public health effect of widespread fires spurred the government to action, shows that efforts to reduce forest loss are most effective when they originate within countries, rather than from outside pressure. “At the end of the day, decisions about whether to continue to allow tree loss cover to take place will be in those countries themselves,” she said.
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Henry Fountain covers climate change, with a focus on the innovations that will be needed to overcome it. He is the author of “The Great Quake,” a book about the 1964 Alaskan earthquake. @henryfountain • Facebook