A warming planet could trigger more intense wildfire season in Hawaii

Updated: Sep. 18, 2018 at 1:18 PM HST
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The Leeward Oahu wildfires came dangerously close to homes in the area (Image: Hawaii News Now)
The Leeward Oahu wildfires came dangerously close to homes in the area (Image: Hawaii News Now)
Dozens of firefighters responded to wildfires over the summer (Image: Hawaii News Now)
Dozens of firefighters responded to wildfires over the summer (Image: Hawaii News Now)
Researchers say certain grasses and shrubs will help spread wildfires more intensely with...
Researchers say certain grasses and shrubs will help spread wildfires more intensely with warmer and drier conditions (Image: Hawaii News Now)

HONOLULU (HawaiiNewsNow) - Residents in West Maui woke up to one of their worst nightmares just a few weeks ago: Two wildfires that scorched roughly 2,000 acres, claiming 21 homes and forcing the evacuations of over a hundred households.

Also this summer: Two raging wildfires broke out in Waianae and Makaha on the same day, burning a combined total of nearly 9,000 acres, sending thick black smoke billowing over residential communities and forcing the closures of two elementary schools.

These were just a few of the many brush fires to break out across the state in the past few months. While wildfires are not uncommon during the summer months due to hotter and drier conditions, scientists agree that what the state is seeing now is a preview of what's to come: A startling uptick in frequency of wildfires across the state and more intense wildfires that will burn over more land.

This increase in wildfire risk is all as a result of climate change, researchers say, that could have serious consequences for Hawaii's communities, infrastructure and native ecosystems.

"We see a very clear trend over the next century, if global warming continues, to warmer temperatures and drier conditions on the dry sides of the islands where we already have a lot of fires," said Kevin Hamilton, University of Hawaii atmospheric science researcher and former director of the International Pacific Research Center. "Warmer temperatures favor more burning."

In Hawaii, wildfires generally ignite during the dry season, typically between May and November, when it's hotter, drier and windier outside.

But models show that the drier leeward areas, where fires are more frequent, will see even less rainfall as a result of climate change, exacerbating drought conditions and expanding the length of Hawaii's dry season.

That means more favorable conditions for brush fires to ignite.

And non-native grasslands and shrubs — which cover nearly a fourth of Hawaii's total land area — are highly adapted to fire, meaning they thrive when they burn and come back really quickly, researchers say. And the drier it is, the harder it is for forests to recover in those spots.

And that could mean larger and more fast-moving fires.

"It's pretty much this pattern where the existing grasslands and shrublands are very easy to burn. They carry fires quickly across really large spaces," said Clay Trauernicht, a wildland fire specialist with the University of Hawaii Cooperative Extension Service. "So as you move into the future, what we're worried about is that the conditions of the forest line are becoming more and more conducive for fires to happen."

A warming planet could trigger more intense wildfire season in Hawaii

Hawaii sees more wildfires

In the past century, Hawaii has already seen a dramatic spike in wildfire occurrence.

Once limited to volcanic eruptions and infrequent lightning strikes, almost all wildfires in Hawaii are now started by humans. And since the early 1900s, the state has also seen a major population boost.

However, climate change can be partly to blame for the increase, researchers say.

"In Hawaii, we've also seen for decades an increase in burning, and we've certainly had a tendency to warmer overall temperatures and drier conditions, particularly on the drier sides of the island," Hamilton said.

"I think if you just keep everything the same — the same lightning, the same human activity — then the future trends are rather negative for the forests."

The risk Hawaii is facing due to wildfires is among a number of effects as climate change takes hold. Those include rising sea levels, which have led to coastal flooding and erosion, along with the threat of more intense tropical systems that could bring catastrophic damage to the islands.

Major threats posed

Hotter days could spell longer-lasting brush fires, meaning more hours for firefighters and greater potential for damage to infrastructure.

And it's only going to get hotter. A regional NOAA report estimates that in Hawaii, temperatures are expected to rise by 4 to 5 degrees by 2085 — under a worst case emission scenario.

"If you have hotter days, the conditions that are going to promote your most active fires — like the hottest, windiest conditions — have the potential to last longer for hours within a span of a day," Trauernicht said, pointing to the Makaha fire that continued burning in the early evening, when temperatures are normally dropping and humidity levels usually go up.

"What we saw was these dry, windy conditions really late in the day, and there's definitely potential for that to change as the air temperature gets hotter with climate change."

Trauernicht adds that the changes in rainfall will mean changes in where the fires are likely to occur, meaning the fires will be pushed mauka, which could not only put it in difficult terrain for firefighters to get to the fires, but it could have a domino effect on Hawaii's ecosystem by threatening watershed forests.

"What we're worried about is as these fires recur over time, is that the watershed forest contracts uphill, and forests capture that better than grasslands do," he said.

Wildfires could even put tropical coastal areas at risk due to runoff, which could ultimately mean the decline of coral reef fish and the health of the coral ecosystems.

But perhaps the biggest threat involving wildfires is to human lives and infrastructure.

Researchers say as agriculture is being abandoned statewide, there's a greater potential for fires to get close to homes and businesses — areas where people have made investments.

In 1980, there were 1.1 million acres in Hawaii in active pasture use. That number dropped to 760,000 acres by 2015.

"It's just the fact that we don't use land the same way we once did, and our big contributor to fire risk is abandonment to agricultural land use," Trauernicht said, adding that farming and ranching are some of the most effective ways to maintain and control wildfires.

"It's really one of the big best tools we can use to reduce the risk."

In place of agricultural land use, communities (like West Oahu) are being developed in fire-prone areas. Planners say before homes go in, developers and government should be looking at wildfire risks.

Leo Asuncion, director of the state Office of Planning and co-chair of the Hawaii Climate Change Mitigation and Adaptation Commission, said strong winds could push fires closer to homes and other properties.

"If you get a strong enough wind, especially out on the west side, the winds can pick up in the afternoon and you get one good burst of wind, you can just jump the barrier, and the houses are out there," Asuncion said.

Trauernicht said developers also need to think of ways — like creating easements — for firefighters to safely get around homes.

"It really comes down to access and water," he said. "And if those elements are in place, it can really enhance the firefighters' ability to put the fire out."

Planning for tomorrow

Experts say if the state doesn't plan ahead now for the wildfire risks associated with climate change, it could be very costly in the long run.

"Whatever's happening now, whatever costs are incurred are going to intensify unless you do something," Hamilton said.

But figuring how much to invest now is also one of the biggest challenges, Asuncion added.

"We know what kind of dollars we're talking about if we have a loss. But then how much of it should be invested now to mitigate or reduce that cost in the future if it happens?" he said. "That we don't have a clear understanding."

Less than six weeks into the new fiscal year, officials had already spent about a third of the state's Division of Forestry and Wildlife's budget for fire and emergency response, including the Kilauea eruption.

"I can only say that the more fires there are going to be, there's going to be a need for more money for wildfire suppression," said Michael Walker, DOFAW fire protection forester.

DOFAW, which manages more than 25 percent of state land, does not currently have any dedicated firefighters. All crew members have day jobs, such as a botanist or wildlife biologist, who are trained and equipped as firefighters.

But as the division prepares for increased wildfire risks, officials are already looking to have full-time fire crews. And the division has also been seeking funding from the Legislature -- as much as $1 million a year over the next 10 years -- to upgrade its firefighting fleet.

"A lot of the machines that we have been using are from the 70s to the 90s, and some break down on the way to fires," Walker said.

Asuncion calls efforts to mitigate the increasing threats of wildfires a multipronged approach, meaning government as well as non-profit organizations are working together. But as there's also a lot of uncertainty around predicting what will happen in the future, the best thing to do is start preparing now.

"Climate change is one of those items where everyone knows it's going to happen," he said. "It's a matter of when."

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