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."

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?”

Is tourism to blame?

The fires come amid an ongoing debate about whether tourism is harming Hawaii's ecosystems.

Earlier this year, Fodor's Travel named Maui among 10 destinations on its 2023 “No List” that tourists should reconsider visiting because of the threat of environmental damage caused by overtourism and climate change.

Clay Trauernicht, a professor of natural resources and environmental management at the University of Hawaii at Manoa, said it would be misleading to simply blame weather and climate for the blazes.

Instead, Trauernicht, who noted in 2018 that the area burned annually by wildland fire in Hawaii has quadrupled in recent decades, pointed to unmanaged, nonnative grasslands that have flourished in Hawaii after decades of declining agriculture.

“These savannas now cover about a million acres across the main Hawaiian islands, mostly the legacy of land clearing for plantation agriculture and ranching in the late 1800s/early 1900s,” he wrote in a series of posts on the social platform X, formerly Twitter.

What's a solution to lessen wildfires in Hawaii?

The transformation to savannas makes the land much more susceptible to the hot, dry and windy conditions that produce such wildfires, Trauernicht said, with much more buildup of fire fuels during rainy periods. Agricultural declines, meanwhile, also make firefighting more difficult as roads become unmaintained, irrigation and water storage lessen and those familiar with the land move away.

“The burden Hawaii’s current fire problem places on emergency responders, the impacts on farms and ecosystems, the losses our community’s experiencing right now – it’s mostly from benign neglect,” he wrote.

While maddening, the situation also offers a glimmer of hope, Trauernicht said.

“Hawaii’s fire problem could be far, far more manageable with adequate support, planning and resources for fuel reduction projects, agricultural land use and restoration and reforestation around communities and the foot of our forests,” he wrote.

Hawaii Wildfire Management Organization, a non-profit based in Waimea on Hawaii Island, said the increasing fires are threatening humans, infrastructure, water quality, agricultural production and natural resources.  

"Hawaii has a wildfire problem," the organization states on its website. "Each year, about 0.5% of Hawaii's total land area burns each year, equal to or greater than the proportion burned of any other US state. Over 98% of wildfires are human-caused. Human ignitions coupled with an increasing amount of nonnative, fire-prone grasses and shrubs and a warming, drying climate have greatly increased the wildfire problem."