Wildfires are burning again in the United States. This time, it’s the South Fork and Salt fires, which started burning last Monday in southern New Mexico. Anomalously dry and windy conditions helped fuel these blazes, which quickly engulfed thousands of acres, triggering widespread evacuations, damaging upwards of 1,000 structures, and tragically killing at least two people.
These events are already awful as immediate human tragedies. But we track wildfires here at CarbonPlan because of the longer term impacts they have on efforts to combat climate change. Along with local communities, the South Fork and Salt fires have burned thousands of acres of the Mescalero Apache offset project (CAR1183), a forest enrolled in California’s offset program. The state’s polluting industries use projects like this to compensate for their carbon emissions.
Based on reports from the ground, we also know that the fires burned at high severity, especially during their initial expansion. High severity fires are especially destructive to trees, which undermines the carbon storage of the offset project. We estimate that the pair of fires burned over 12,000 acres. Because the carbon stored by the forest is used by polluters in California to justify their ongoing emissions, that lost carbon will need to be compensated for by the program’s buffer pool, a reserve of credits held as insurance for when offset projects are damaged.
Based on the size and severity of this pair of fires, it seems all but inevitable that the program's buffer pool will take a hit. It’s difficult to precisely estimate the magnitude of those losses. Previously, we’ve relied on US Forest Service data on fire severity to estimate the number of offset credits lost from large fire events. However, those data can take weeks to months to become available.
Even without precise data, we can come up with a back-of-the-envelope estimate. We know 12,600 acres burned and, according to project paperwork, the project stores an average of 35.6 tCO₂ per acre. Let’s assume half the acres burned at high severity, which kills 90 percent of standing live trees. Setting aside any carbon recovered from salvage harvests, multiplying everything together (acreage: 12,600; severity: 0.5; mortality: 0.9; carbon stocks: 35.6) yields 201,852 offset credits lost. This estimate is mostly useful to gauge the order of magnitude of the potential loss. Because projects have latitude in how they account for wildfire losses, we’ll need to wait for more data and paperwork to learn more.
Fires like South Fork and Salt can further destabilize California's already shaky offset program. Every time projects enrolled in the program are substantially damaged by fire, the state has to dip into the program’s buffer pool. And while new credits might be added to the buffer pool over time, the losses take a toll, just like losses against any insurance program. Evidence shows that those losses are stacking up in ways that could undermine the long-term integrity of California’s program.
If we’re going to use offsets to counteract climate change, we need the programs to do a better job of taking the risks of wildfires into account.