In some parts of California, the fires from last year never stopped. The U.S. National Park Service said this week it found a giant sequoia tree still burning from last year’s wildfire season, which was the worst on record in the state.
The smouldering sequoia was found in a remote section of the Sequoia National Park, where the lightning-ignited Castle Fire raged last September. Other trees in the region were still burning or smoking from the fire as recently as last month. They’re essentially zombie tree fires, compatriots to Siberia’s zombie fires that overwinter in peat-rich soil and have made headlines in recent years.
“The fact areas are still smouldering and smoking from the 2020 Castle Fire demonstrates how dry the park is,” Leif Mathiesen, assistant fire management officer for Sequoia and Kings Canyon National Parks in central California, told the AP. “With the low amount of snowfall and rain this year, there may be additional discoveries as spring transitions into summer.”
Sequoias are a type of redwood tree, the iconic giants of the West Coast that can live up to 3,000 years and grow up to 76 metres tall. They’re also pretty hardy trees — you would be too if you had to survive several centuries — and have developed strong defences against normal fires, including thick bark and shielding the forest floor to prevent smaller competitors that could allow fires to spread from taking root.
But California’s drought and the increasingly intense wildfires have been taking a toll on them. In the midst of California’s seven-year drought in the 2010s, some sequoias experienced foliage dieback — a rare phenomenon for the trees — while dry conditions and fires have made the trees susceptible to bark beetle infestations, increasing the odds of more destructive fires that can wipe out groves. Scientists say that the Castle Fire alone likely killed hundreds of trees last year.
“This fire could have put a noticeable dent in the world’s supply of big sequoias,” Nate Stephenson, a research ecologist with the U.S. Geological Survey, told the LA Times in November.
And Mathiesen is right that this tree still burning is a bad sign for the rest of the season. In March, the U.S. National Oceanic and Atmospheric Administration predicted that more than half the U.S. may see drought conditions through their spring and summer. Snowpack in the Sierras this winter failed to live up to expectations, and California is already in dire drought straits. According to the Drought Monitor, more than 73% of the state is in extreme or exceptional drought, up from roughly 13% when the water year began last October.
The increasing drought and still-smolder fires portend an ominous fire season to come. And that’s the last thing California needs; five of the state’s six largest wildfires on record happened in 2020, at least 30 people were killed, and one of the megafires in the north of the state surpassed 1 million acres, making it the first “gigafire” in modern California history. An analysis of more than 100 studies found that climate change played an “unequivocal and pervasive” role in making last year as bad as it was. This all fits with a larger pattern; climate change is driving the Southwest into the worst megadrought in more than a millennium.
Whether it leads to more zombie fires in giant trees isn’t something scientists have modelled, but I’m not exactly eager to see what nature will throw at us next if the world keeps heating up.