Why the Hawaii wildfires proved so devastating and deadly

The exact causes of the fires, which started on Tuesday (August 8) night, have not yet been determined. However, the National Weather Service had issued warnings for the Hawaiian Islands for high winds and dry weather - conditions ripe for wildfires - as Hurricane Dora brushed south of the Pacific island chain.

Craig Clements, a meteorology professor at San Jose State University, said Maui had already been in drought conditions, putting it at greater risk of fires this year than California. He said the steep mountains overlooking the hard-hit town of Lahaina exacerbated the high wind conditions that fueled the flames and sent them into populated areas at high speed.

"So that part of Maui has a very steep mountain range. And the winds were coming from the northeast and they were very strong winds. They were descending, going up and over the mountain range and descending what we call the lee side. And when that happens, you get acceleration near the surface. And so you get actually faster winds on the downslope side or the lee side of a mountain range. And this happens in California. The Santa Ana winds, the Diablo winds. Santa Barbara, California, is susceptible to this as well with the sundowner winds. So a lot of mountain coastal communities have this situation."

"And what people don't realize is that Hawaii was under or sorry, Maui was in a D1, D2 severe drought for the season and the risk for large fire potential was higher there than it was in California for this month and last month and in September as well. So all these conditions lined up with kind of a classic fire weather situation. It just so happened that there was ignition during the high wind event, allowing a very fast spreading fire to burn into the community towards the coast."

Elizabeth Pickett, the co-executive director of Hawaii Wildfire Management Organization, said the growing presence of highly-flammable non-native grasses on the island, added to the risk level.

"Do we have this additional issue, which is that our island archipelago has been invaded by fire-prone grasses from all over the world? And so now we have this invasive species issue that has moved into all those fallow agricultural lands. And the problem is so big. I mean, over a million acres, and that's big for a small island. It's 26% of our state."

"These are grasses that spread with fire. So when our native forest burns, what comes back is more of these grasses. And so we have this grass fire cycle, we call it, where we keep getting more and more grasses. So, you know, there's history and economics involved, but in the end, it's a fuels management problem. And then when you couple that with community development styles and infrastructure setups that were never meant to withstand wildfire because it didn't use to be an issue, there's a lot of retrofitting that needs to happen."

" Non-native vegetation can fill in gaps that are usually not areas where you could have a carrier of the fire. So this happens in the western U.S. with grass where you have a sage ecosystem. So shrub land, but a fire spreading from a shrub to shrub is more difficult than a fire spreading from a shrub to the grass carrying it to the next shrub. So invasive grasses can actually cause fires to be easier to spread," Clements said. 

Erica Fleishman, director of the Oregon Climate Change Research Institute, said there are ways to limit the risk to residences and other buildings, such as retrofitting ventilation systems to prevent them from ingesting the sparks that perpetuate wildfires.

"When you have higher temperatures, you have more evaporation of water. And also you can think of it as plants being thirstier. So plants use more water when the air temperature is higher. So the water that is present tends to disappear more rapidly, disappear from use by plants, disappear from use by humans. Now, the water is still in the global water cycle, but in essence, it's less available to humans and less available to plants as temperatures increase."

"And also, if you rebuild, can you rebuild in ways that are more resistant to future extreme events that will happen? So there's a lot that can be done. Not always easy, not always cheap, but rebuilding structures so that they are more resistant to wildfire. So many structures ignite because sparks moving far in front of the fire front get into the ventilation system of the building and there are ways to construct buildings so that the ventilation systems, it's less easy for the ventilation systems to take up sparks. You can have fire-resistant roofs. You can be doing different things with decks, with materials next to structures. So, I mean, there are possibilities for saying a wildfire is likely to happen in the future, but perhaps buildings don't burn down. Perhaps people can protect themselves better from smoke or have better alert networks, evacuation networks, I mean, all kinds of systems to say if we accept as a society that these events will happen again, how can we best protect ourselves and the things we care about from those events?"

"After a big event like this, a devastating event like this, there's always an in-depth study and analysis of not only the fire behaviour in the weather and the conditions that caused it but what actions did the emergency management take? You know, I mean, I read reports that the 911 system went down. And so, you know, redundancies there need to be implemented. I mean, there's a lot of things that are going to have to change," Clements said.

Reuters