Scorched earth

 作者:敖汰     |      日期:2019-02-26 09:12:00
By Fred Pearce THE heat and drought that helped trigger Indonesia’s disastrous forest fires in recent weeks are wreaking havoc in South America, according to satellite data. Fires are raging through the Brazilian rainforest faster than in the late 1980s, when the burning made the region the focus of international environmental concern. The Brazilian Amazon and Indonesia contain the world’s two largest surviving regions of rainforest. The US government’s NOAA-12 satellite spotted more than 24 000 fires in the Brazilian Amazon between early August and mid-September, the height of the burning season. This is a 28 per cent increase on the previous year, the satellite’s first year on fire watch. The blaze has also spread to neighbouring Colombia. The fires, most of which are started by farmers, show up as temperature anomalies in night-time data from the satellite’s Advanced Very-High Resolution Radiometers. Stephan Schwartzman, an anthropologist from the Environmental Defense Fund in Washington DC who analysed the data, says the satellite will not spot all fires—some are too small or are extinguished before nightfall. Even so, NOAA-12 identified an average of 600 every night during a watch that lasted over 40 days. Numbers of fires do not correspond precisely with deforestation rates. Many fires are lit to maintain cattle pastures already cleared from the forest. And much burning of virgin forest takes place unseen beneath the canopy. But Schwartzman says that “increased burning strongly suggests that deforestation rates continue to rise”. He estimates that the current total deforestation rate is probably higher than at its previous peak in 1988, standing at around 20 000 square kilometres a year. The hot, dry conditions in the tropics that promote forest fires have been caused by the El Niño climate anomaly,