Earlier this month, a fire started in Las Tusas, New Mexico, that burned almost 1,000 acres of land.
The blaze was a searing reminder of last year’s wildfire season. The Calf Canyon/Hermits Peak fire – the worst in New Mexico history – burned more than 300,000 acres, leaving a scar that could take decades to fully recover. Suppressing the fire cost hundreds of millions.
New Mexico is now in the midst of its fire season — a season that has become longer and more intense over the past years following long-term climate changes, including stronger, drier storms and an increase in vapor pressure deficit, a measurement that looks at how the air dries out vegetation.
But there’s some good news. This fire season is likely to be dampened, due to changing weather patterns in the state.
Andrew Church, a New Mexico-based meteorologist and resident fire weather and climate expert for the National Oceanic and Atmospheric Administration, said that the state is seeing opposite storm patterns to last spring, when several fires spiraled out of control throughout the state.
“You had three La Niña winters in a row, and then suddenly, we’re going to be in El Niño in the next few weeks,” Church said. “So there was a huge change.”
El Niño weather patterns bring more moisture and snow to New Mexico than La Niña, which brings drier and warmer temperatures – conditions that provide kindling for wildfires.
High winds and dry conditions are two of the biggest factors that can spark wildfires and whip them into a destructive frenzy; thus, a wetter winter and spring helps quell the fire season.
“We just had a meeting, a fire weather meeting here with the land agencies and the dispatch centers there,” Church said. “We’ve got fire behavior analysts and they were just discussing the moisture we have now. It’s going to limit a fire season … it’s a very good thing.”
Short-term relief, long-term trends
Church said over the next months, wildfire danger should creep north into other Southwestern states, which don’t see the same spring moisture that New Mexico does. Generally, Church said, New Mexico has an earlier fire season and rarely sees late summer wildfires.
But, despite the reprieve that New Mexico is expected to see this year, long-term trends have been prolonging and intensifying fire seasons throughout New Mexico and the Southwest. Over the past decade, storm systems have become more erratic in the state, Church said, with many storm systems coming in drier, with more intense winds — drying out vegetation that can fuel fires.
One of the factors that has turned New Mexico and other western states into a tinderbox is an increase in vapor pressure deficit, or VPD, an important metric in the study of wildfires.
“VPD is a measure of how effectively the air can dry out the plants and the vegetation that ultimately becomes fuel for wildfires,” said Kristina Dahl, a climate scientist with the Union for Concerned Scientists. “VPD tends to be high when it’s hot and dry out … and as VPD increases, so does the area burned by forest fires.”
Elevated VPD can dry out vegetation in forests — and levels have been rising, along with increased severity and length of fire season in Southwestern states. A group of researchers with the Union for Concerned Scientists published a peer-reviewed study last Tuesday in Environmental Research Letters relating VPD to an increase in burned areas in the western United States and southwestern Canada from 1986.
“There’s a very strong relationship between VPD and burned area,” Dahl, the principal researcher on the study, said. “It’s actually an exponential relationship – so very small changes, very small increases in VPD, cause very large increases in burned area.”
The link between rising VPD and an increase in burned areas has been studied before. But the new study goes further, tracing the roots of increased VPD to the 88 largest carbon emission producers.
When the weather is hot and dry, VPD increases. Over the past decades, as carbon emissions have pushed temperatures higher, VPD has correspondingly increased, Dahl said. The team of researchers calculated VPD using observational data from weather stations, and compared it to global mean temperature data from 28 different climate models compiled by the World Climate Research Programme’s Coupled Model Intercomparison Project, which compares a variety of different climate models for a more holistic look at the world’s climate. From there, the team used data tracked by public records pulled by researcher Richard Heede of the largest carbon polluters to determine how much they contributed to the rise in VPD.
The study found that emissions traced to the 88 largest carbon producers contributed 48% of the rise in VPD between 1901 and 2021. Other contributors included smaller companies as well as other factors including deforestation.
But the destruction of wildfires isn’t limited to burned areas. Church cautioned that although less area may burn this season, burn scar areas around the state are more susceptible to flooding due to monsoons. Although the monsoon season is predicted to be mild, Church said, just one thunderstorm in the wrong area can cause intense flood damage.
Although the state will likely see less thunderstorm days than last year, Church said, burn scar areas are most vulnerable in the second year.
“It just takes one storm, or a couple of storms, to wreak havoc on burn scars,” Church said. “Don’t let your guard down.”