New Mexico and Arizona are facing an alarmingly early fire season. It has left neighborhoods in ashes and is having such devastating effects that on May 3, 2022, the governor of New Mexico urged President Joe Biden to issue a disaster declaration. There were more than 600 fires in both states in early May, and large wildfires burned in Ruidoso and hundreds of homes near Las Vegas, New Mexico and Flagstaff, Arizona.
We asked Molly Hunter, a wildfire scientist at the University of Arizona, to explain what causes extreme fire conditions and why such risky weather is becoming more common.
Why is wildfire season so early and intense this year in the Southwest?
Fires are natural in the Southwest, but fire seasons are getting longer and more intense.
Historically, the fire season in the Southwest did not extend until late May or June, because the fuels that ignited the fires – mainly wood debris, leaf litter and dead grass – had not dried up completely by then.
Now, the southwest is seeing fires very early in the season. Unfortunately, the timing coincides with the time when the area typically experiences strong winds that can promote rapid fire development. Some of the fires we’re seeing this year, like the tunnel fire near Flagstaff and the fire in New Mexico, are being driven by these really intense wind events. Those are pretty typical winds for spring, but the fuels are now really dry and ready to burn.
The earlier fire season is partly due to the warmer climate. As temperatures rise, snow melts more quickly, more water evaporates into the atmosphere, and grass and other fuels dry out earlier in the season.
This year we also have a lot of fuel to burn. Last summer, in 2021, the southwest had an exceptional monsoon season that left green hills and lots of vegetation. So far, established grasses and thorns have dried up during the monsoon, leaving a lot of biomass that can lead to fires. Often in the Southwest, our biggest fire years come when we have wet periods followed by dry periods, such as the La Nia conditions we are experiencing now.
What role does climate change play?
In the Southwest, climate change means hot, dry conditions. One immediate effect is the lengthening of the fire season.
Now we see that the fire starts in March and April. And if the southwest doesn’t get a good summer monsoon—the region’s typical period of heavy rain—fire season won’t really stop until we get significant rainfall or snowfall in the fall and winter. This means more stress on firefighting resources, and more stress on communities facing fire, smoke and evacuation.
As the fire season lengthens, states are also seeing more fires caused by human activities, such as fireworks, sparks from vehicles or equipment, and power lines. More people are moving out to fire-prone areas, creating more opportunities for human-caused ignition.
How is the changing fire regime affecting the ecosystems of the Southwest?
When fires burn in areas that haven’t historically seen fires, they can change ecosystems.
People don’t usually think of fire as a natural part of desert ecosystems, but grass is now causing really big fires in the desert, like Arizona’s Telegraph Fire in 2021. These fires are spreading further and in different ecosystems as well. Telegraph fires began in a desert system, then burned in the chaparral and mountains, along with pine and coniferous forest.
Part of the problem is invasive grasses like buffalo grass and red brom spread quickly and burn easily. Those desert systems now have a lot of grass growing, making them more prone to wildfires.
When desert fires spread, some plant species, such as mesquite and other brush plants, can survive. But saguaros – the iconic cactus that are so popular in Southwest tourist destinations – are not fire-friendly, and they often die when exposed to fire. Paloverde trees are also not well adapted to survive fires.
What comes back quickly is grass, both native and invasive. So in some areas we are seeing a transition from a desert ecosystem to a grassland ecosystem which is very conducive to the spread of fire.
The Cave Creek Fire near Phoenix in 2005 is an example where you can see this transition. It burned over 240,000 acres, and if you drive around that area now, you don’t see a lot of saguaros. It doesn’t look like a desert. It looks like an annual meadow.
It is an iconic landscape, so the loss affects tourism. It also affects wildlife. Many species depend on the saguaro for nesting and feeding. Bats depend on flowers for nectar.
What can be done to avoid higher fire risk in the future?
In some cases, people have to understand that fire is inevitable.
The fire has now exceeded our ability to control them. When the winds are strong and the fuel is really dry, there is only so much firefighters can do to stop these big fires from spreading.
Conducting more scheduled fires to put out potential fuel is an important way to reduce the likelihood of a really large, catastrophic blaze.
Historically, far more money went into fighting fires than managing fuel with tactics like thinning and scheduled fires, but the infrastructure bill signed in 2021 included a huge influx of funds for fuel management. There is also a push to move some seasonal fire crew jobs to full-time, annual positions for tapering and scheduled burns.
Homeowners may also be better prepared to live with a fire. This means maintaining yards and homes by removing debris so they are less likely to burn. It also means being prepared to evacuate.