An extensive analysis of satellite imagery has uncovered thousands of miles of unmapped roads slicing through Asia’s tropical rainforests.

So-called “ghost roads” may be laid down by miners, loggers, poachers, drug traffickers, and land grabbers, often illegally. In Southeast Asia, the reach of such roads is “severely underestimated, with many roads being out of government control,” said Bill Laurance, of James Cook University, coauthor of the new study.

For the study, 200 volunteers spent more than 7,000 hours scanning satellite images of Borneo, Sumatra, and New Guinea. In total, they traced more than 800,000 miles of roads, at least three times as much road as found on widely used maps, such as OpenStreetMap. The findings, published in Nature, line up with similar inventories of “ghost roads” in Cameroon, the Solomon Islands, and Brazil.

Researchers say that “ghost roads” allow intruders to reach deep into the jungle, and they warn that road-building typically precedes the destruction of rainforest. Roads make it possible for invaders to raze forest, eradicate wildlife, and drive out Indigenous people. Said Laurance, “In these findings, nature is the big loser.”

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