Officials are unsure what started the ongoing blazes in Maui that have killed six people, forced hundreds of evacuations, torched structures, left thousands without power and prompted some locals to bolt into the ocean to escape marauding flames. But some experts said they suspect human development on the island is at least partly to blame for the destruction.

Wildfires have quadrupled in Hawaii in recent decades, and many scientists say the culprit is unmanaged, nonnative grasslands planted by plantations and ranchers and others unfamiliar with the island’s native ecosystems. The grass is dry and prone to fires.

“There is no doubt that fire-prone grasses have invaded drier Hawaiian ecosystems and brought larger, more intense fires,” said Peter Vitousek, a professor of earth sciences at Stanford University in Palo Alto, California.

What caused the Maui fires?

High winds and low humidity likely contributed to the fires, but officials know little else, said Maj. Gen. Kenneth Hara, commander general of the Hawaii Army National Guard, at a briefing Wednesday.

“We don’t know what actually ignited the fires, but we were made aware in advance by the National Weather Service that we were in a red flag situation — so that’s dry conditions for a long time, so the fuel, the trees and everything, was dry,” he said, according to CBS News.

Hurricane Dora, a Category 4 storm in the Pacific Ocean, fueled the strong winds overnight in Maui, with gusts of 60 miles per hour damaging homes and knocking out power.

State officials activated the Hawaii National Guard to assist police in Maui, where the areas most impacted include Lahaina, a residential and tourist area with a commercial district in West Maui; Kula, a residential area in the inland, mountainous Upcounty region; and Kihei, a mix of homes, condos, short-term vacation rentals and visitor facilities in South Maui.

Wildfires were uncommon before humans arrives in Hawaii

Aside from areas with active volcanoes, wildfires were uncommon in the Hawaiian islands prior to the arrival of humans, said David Beilman, a professor of geography and environment at the University of Hawaii at Manoa. This more recent era in Earth’s history, in which human activity has impacted climate and ecosystems, is unofficially referred to as the Anthropocene Epoch.

“On the other islands with less volcanic activity, fires did occur, but very, very rarely,” Beilman said. “This Maui situation is an Anthropocene phenomenon.”

This photo provided by the County of Maui shows fire and smoke filling the sky from wildfires on the intersection at Hokiokio Place and Lahaina Bypass in Maui, Hawaii on Tuesday, Aug. 8, 2023. Wildfires in Hawaii fanned by strong winds burned multiple structures in areas including historic Lahaina town, forcing evacuations and closing schools in several communities Wednesday, and rescuers pulled a dozen people escaping smoke and flames from the ocean.

Kaniela Ing, national director for the Green New Deal Network and an Indigenous leader in Hawaii, said the wildfires offer further proof of a dangerous climate emergency.

“We need legislation that is as bold and urgent as the scale of the wildfires choking Hawaii and Canada, the heatwaves suffocating Texas, and the extreme flooding drowning Europe,” said Ing, a former state legislator in Hawaii. “How many more lives lost or families displaced in communities like mine is President Biden willing to tolerate before he declares a climate emergency and activates politicians to take further climate action?”