“If 2019 had been a drought year, we probably would have had a very, very, very big disaster,” says Paulo Brando, an ecosystem scientist at the University of California, Irvine. The 2019 fires largely did not move into primary forest and were confined to areas near deforested patches, because those larger swaths of forest had moist understories that resist catching ablaze. But the study estimates that without deforestation, these potential burned areas could be reduced by 30 percent, and greenhouse gas emissions cut by 56 percent. Not only is this due to the fires people light in the process of clearing rainforest, but also because of the exposed forest edges that deforestation creates. Brando says those edges become vulnerable areas where human activities could ignite a fire. When there are more forest areas adjacent to farms, roads, and cities, there’s a greater risk of people—intentionally or unintentionally—starting a fire along those borders. Brando explains that it’s similar to melting a large volume of ice in water in one block versus many smaller cubes; just as in the latter situation the ice melts faster, a forest with many chunks catches on fire easier. However, continued deforestation in the model eventually makes the forest too fragmented to spread a fire. That’s why later in the simulation the forests in protected areas and indigenous lands become more likely to burn than the unprotected areas. As if the results aren’t scary enough, they might actually be conservative estimates. Brando based the deforestation rates on those between 2004 and 2014, when deforestation was slowing down. In recent years, it’s picked back up. “Our deforestation rates are actually much more conservative than the current one,” says Brando. “The 2019 path could set up for even more [wildfires].”
