Why Hawai'i Is Facing California-Like Risks For Wildfires

Nov 8, 2019

Climate change could be creating conditions in Hawai'i similar to those in California, where wildfires have devastated parts of the state, according to a University of Hawai'i wildfire expert.

“I've had some folks ask in the past, 'Are we looking at similar situations to California, where they're getting really high wind, drought, low relative humidity?' And I would always kind of say, 'No, not really. We haven't seen that kind of stuff yet,'” said Clay Trauernicht, wildland fire specialist with the UH College of Tropical Agriculture and Human Resources. 

He said that's changing.

This year has been a particularly significant year for wildfires in Hawai'i, especially on Maui. In July, two fires burned more than 9,000 acres in Central and West Maui over four days, closing roads, diverting airline flights and triggering evacuations. Last month, over 4,000 acres burned in Maalaea, again shutting roads and forcing residents from their homes.

What's changing can be seen on the thermometer alone. This summer, Maui broke 33 maximum temperature records, according to the National Weather Service.

Maui firefighters told Trauernicht that the conditions they faced while fighting the Waiko Road fire in July were unlike anything they had ever seen. They pointed to the potential effects of climate change that could be driving the uncontainable speed at which the fire moved across the grassland.

“That was during one of those days where the temperature was about nine degrees above average, really hot conditions, very low humidity,” Trauernicht said. “It's very well within reason to expect that if the firefighters are starting to encounter conditions that they've not experienced in their careers, that it would be able to occur on any of these islands. All those combinations of factors that we saw in Maui this summer is possible to see on other islands for sure.”

Mike Walker, a fire protection forester with the state Department of Land and Natural Resources, traces Maui’s high number of wildfires back to the shutdown of the Hawaiian Commercial and Sugar Co.

The company completed its last harvest in December 2016. Since then, farmland that once grew sugarcane has gone fallow and dry, said Walker. What’s grown in place of the sugar crop is the invasive and highly flammable Guinea grass. 

“Rather than having an irrigated managed sugarcane crop, you have this large expanses of African grasses that are incredibly flammable,” Walker said.

A new study just out from two universities found that invasive grass species are making wildfires more frequent in states like California. The areas burning recently in that state have been more shrubs and grasses than forests, according to experts cited by the Associated Press.

"This is a global problem," said University of Alberta fire expert Mike Flannigan, who wasn't part of the study but said it makes sense. "I think with climate change and human assistance we are moving to a grass world. One region they should have mentioned is Hawai'i where wildfires are increasing in large part due to invasive grasses."

Invasive species are spreading more because of climate change as warmer weather moves into new areas, said the study's lead author, Emily Fusco of the University of Massachusetts. 

In Hawai'i, the growth of inavsive grassses followed the large decline in agriculture cultivation since the 1960s.

Trauernicht said the loss of agriculture lands did not just expand the cover of fire-prone grasses, but limited the resources firefighters could use to handle fires.

“When they would show up at one of these areas [in the past], a lot of times there would be people there to help put the fire out with water tenders, machinery,” Trauernicht said. “So you have kind of more area ready to burn, and less resources available to assist firefighters in putting them out.”

Another development beginning in the 60s: conversion of agricultural land for residential use.

“The most profitable farm product you can have is to farm houses,” Walker said. “Once these lands come up for sale and get converted into residential housing, they're just right adjacent to other parcels that have not been sold yet or converted.”

Seventy-five percent of fires are started as a result of accidental ignition by humans engaging in activities such as operating machinery and parking cars over tall grass.

“We’ve got really high rates of ignitions,” Trauernicht said. “People are kind of the primary cause of the fires that we get here, anytime you mix new developments in some of these fire-prone areas.”

Because the Leeward coast of all the islands, including O'ahu, have drier, hotter and windier conditions, those areas are most at risk for wildfires.

To lessen the chances of damaging fires, both Walker and Trauernicht suggest reducing fuels around the home. Have an evacuation plan and create fuel brakes, such as keeping grass short and using trees for shade.

Walker also suggested planting native plants such as naupaka, a bush that would resist fire.