California wildfires in 2020 wiped out years of greenhouse gas emissions cuts

Planet-warming greenhouse gases like carbon dioxide (CO2) often come from burning fossil fuels like oil, gas or coal.

But CO2 can also spew from burning wood — and when a massive wildfire breaks out, it can burn through a whole lot of wood.

In 2020, California had one of its worst fire seasons on record, burning through more than 4.3 million acres, nearly twice the size of Yellowstone National Park. Now, a new study finds that all those fires burned enough material to negate greenhouse gas emissions reductions that took nearly 20 years to achieve.

“Wildfire emissions in 2020 essentially negate 18 years of reductions in greenhouse gas emission,” Michael Jerrett, an environmental health researcher at the University of California, Los Angeles (UCLA) and one of the study authors, said in a press release.

The 2020 wildfires in California released the equivalent of 127 million tonnes of CO2, the authors found, about the same 27 million cars driven for one year.

That single wildlife year undid years of state progress on the climate crisis. Between 2003 and 2019, California was able to reduce its yearly emissions by the equivalent of 65 million tonnes of CO2 — from 483 million tonnes to 418 million tonnes — meaning the fires wiped out almost two times the yearly reductions.

Over time, much of that carbon could be re-absorbed as the landscape is restored and CO2 is pulled out of the atmosphere to power the photosynthesis needed to grow trees and other plants. But this likely won’t happen fast enough to meet emissions reduction targets, the study notes.

With such potential damage, wildfires are becoming a growing and important source of greenhouse gas (GHG) emissions in California, they conclude. The study was published this month in the journal Environmental Pollution.

“To put this into perspective, without considering future vegetation regrowth, emissions from the 2020 wildfires could be the second most important source of GHG emissions in the state of California,” Miriam Marlier, an environmental health researcher at UCLA and another study author, said in the release.

California has been a leader — both nationally and internationally — in reducing emissions and stemming the root causes of the climate crisis. Just this year, lawmakers approved a plan to ban the sale of new gas cars in the state by 2035, and the state government has proposed a plan to make California fully carbon-neutral by 2045, among other initiatives.

But California also faces some of the direst threats from the climate crisis as wildfires, drought and punishing heatwaves are set to grow stronger and more common on a rapidly warming planet.

The eight largest fires in state history have all occurred in the past five years — with five of them burning during the record-setting 2020 wildfire season. That includes the August Complex, the largest fire in state history, which burned through an area more than three times the size of Los Angeles.

The 2020 wildfires killed 33 people and damaged more than 11,000 structures, according to Cal Fire.

While that fire season was extraordinarily destructive, such devastating years are likely to occur more and more often as the climate crisis grows and increases the likelihood of devastating drought and heatwaves, conditions that can easily spark dangerous blazes.

A 2018 climate assessment from the California state government found that the average area burned could increase 77 per cent by 2050.

And by releasing even more CO2 into the atmosphere, spurring even further warming, those fires risk creating a dangerous climate feedback loop.