As if the oil palm monoculture weren't enough, Borneo possesses another resource that combines economic blessing and environmental danger: The 300-million-year-old plant material that once grew on what is now Borneo lies underground, transformed into coal. Surface mines—for gold as well as coal—spread across southern and eastern Borneo like pockmarks, displacing forest and polluting rivers with waste.

And in a world newly awakened to the dangers of climate change, Borneo has gained global attention for yet another reason: A specialized ecosystem called peat swamp forest covers around 11 percent of the island. Here, trees grow on highly organic soil built of centuries' accumulation of waterlogged plant material. Sometimes reaching a depth of 60 feet, peat soil represents a massive store of the world's carbon. Stripped of its trees and drained, tropical peat decays and releases its carbon into the atmosphere, and as it dries it becomes extremely susceptible to burning, intentional or accidental. Massive annual fires set deliberately to clear previously forested land for new oil palm plantations—and exacerbated by frequent drought—have burned out of control and filled Borneo's skies with smoke, closing airports and causing respiratory problems for millions of people as far away as mainland Asia. Carbon released by decaying peat soil, fires, and deforestation has pushed Indonesia into third place among nations as a source of greenhouse gases, behind only heavily industrialized China and the United States.

Time is running out for Borneo's rain forests. Conventional models offer little hope. Setting aside large areas as parks or reserves, standard practice in the U.S. and other countries, has been largely ineffective, at least on the Indonesian part of Borneo, undermined by inadequate funding, lack of support from local residents, and government corruption. But many conservationists say that logging, often regarded as anathema to wildlife, may, if practiced sustainably, in fact help to protect a significant portion of the island's biodiversity.

"Virgin rain forest is a dead concept now in Borneo," says Glen Reynolds, chief scientist at the Danum Valley Field Center in Sabah. "All of the big areas of primary lowland forest that can be conserved already have been. It's difficult, but now what you've got to do is convince people that what we think of as degraded forest can sustain biodiversity."