Future climate risks from stress, insects and fire across US forests

Anderegg, William R. L.; Chegwidden, O.; Badgley, Grayson; Trugman, Anna T.; Cullenward, Danny; Abatzoglou, John T.; Hicke, Jeffrey A.; Freeman, Jeremy; Hamman, Joseph

doi:10.1111/ele.14018

Cited by 63 publications

(62 citation statements)

References 50 publications

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“…Historical carbon losses from wildfires are chiefly the result of the record-breaking 2020 and 2021 western U.S. fire seasons, which are unfortunately representative of the kinds of accelerating climate risks expected across the American West in a changing climate (Abatzoglou & Williams, 2016; Anderegg et al, 2022). Looking forward, wildfires are expected to grow in both size, intensity, and frequency as a result of anthropogenic climate change (Barbero et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

California’s forest carbon offsets buffer pool is severely undercapitalized

Badgley

Chay

Chegwidden

et al. 2022

Preprint

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California operates a large forest carbon offsets program that credits carbon stored in forests across the continental United States and parts of coastal Alaska. These credits can be sold to buyers who wish to justify ongoing emissions, including in California’s cap-and-trade program. Although fossil CO2 emissions have effectively permanent atmospheric consequences, carbon stored in forests is inherently less durable because forests are subject to significant socioeconomic and physical risks that can cause temporarily stored carbon to be re-released into the atmosphere. To address these risks, California’s program is nominally designed to provide a 100-year guarantee on forest carbon claims based on a self-insurance program known as a buffer pool. Projects contribute credits to the buffer pool based on a suite of project-specific risk factors, with buffer pool credits retired as needed to cover carbon losses from events such as wildfire or drought. So long as the buffer pool remains solvent, the program’s permanence claim remains intact. Here, we perform an actuarial analysis of the performance of California’s buffer pool. We document how wildfires have depleted nearly one-fifth of the total buffer pool in less than a decade, equivalent to at least 95% of the program-wide contribution intended to manage all fire risks for 100 years. We also show that potential carbon losses from a single forest disease, sudden oak death, could fully encumber all credits set aside for disease and insect risks. These findings indicate that California’s buffer pool is severely undercapitalized and therefore unlikely to be able to guarantee the environmental integrity of California’s forest offsets program for 100 years.

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Section: Discussionmentioning

confidence: 99%

California’s forest carbon offsets buffer pool is severely undercapitalized

Badgley

Chay

Chegwidden

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Historical carbon losses from wildfires are chiefly the result of the record-breaking 2020 and 2021 western United States fire seasons, which are unfortunately representative of the kinds of accelerating climate risks expected across the American West in a changing climate (Abatzoglou and Williams, 2016; 10.3389/ffgc.2022.930426 Anderegg et al, 2022). Looking forward, wildfires are expected to grow in both size, intensity, and frequency as a result of anthropogenic climate change (Barbero et al, 2015).…”

Section: Wildfirementioning

confidence: 99%

California’s forest carbon offsets buffer pool is severely undercapitalized

Badgley

Chay

Chegwidden

et al. 2022

Front. For. Glob. Change

Self Cite

View full text Add to dashboard Cite

California operates a large forest carbon offsets program that credits carbon stored in forests across the continental United States and parts of coastal Alaska. These credits can be sold to buyers who wish to justify ongoing emissions, including in California’s cap-and-trade program. Although fossil CO2 emissions have effectively permanent atmospheric consequences, carbon stored in forests is inherently less durable because forests are subject to significant socioeconomic and physical risks that can cause temporarily stored carbon to be re-released into the atmosphere. To address these risks, California’s program is nominally designed to provide a 100-year guarantee on forest carbon claims based on a self-insurance program known as a buffer pool. Projects contribute credits to the buffer pool based on a suite of project-specific risk factors, with buffer pool credits retired as needed to cover carbon losses from events such as wildfire or drought. So long as the buffer pool remains solvent, the program’s permanence claim remains intact. Here, we perform an actuarial analysis of the performance of California’s buffer pool. We document how wildfires have depleted nearly one-fifth of the total buffer pool in less than a decade, equivalent to at least 95 percent of the program-wide contribution intended to manage all fire risks for 100 years. We also show that potential carbon losses from a single forest disease, sudden oak death, could fully encumber all credits set aside for disease and insect risks. These findings indicate that California’s buffer pool is severely undercapitalized and therefore unlikely to be able to guarantee the environmental integrity of California’s forest offsets program for 100 years.

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“…While tropical forests specifically store most land biomass ( Pan et al, 2013 ), most are now secondary ( FAO, 2020 ) and functionally degraded ( Hubau et al, 2020 ). This likely amplifies amid increasing climate stressors ( Anderegg et al, 2022 ) and collective management issues, including insufficient policy support ( Chazdon, 2018 ) via skewed priorities ( Pyron and Mooers, 2022 ). Overall, secondary forests can regenerate relatively quickly compared to old-growth forests, in some ways.…”

Section: Introductionmentioning

confidence: 99%

Habitat edges affect tree diversity more than biomass regeneration in a reforested wet neotropical timber plantation

Medina

Capetz

Johnson³

et al. 2022

Preprint

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About half of all forests are tropical and secondary, making tropical forest regeneration integral to future forests. Tree stand biomass and taxonomic richness can recover in a few decades, but relative abundances may lag indefinitely. Since most forests are within a km of a habitat edge, edge effects likely affect community composition regeneration. However, most studies assess how degraded edges affect intact forests, leaving it unclear whether higher-quality edges could facilitate regeneration of nearby degraded forests. Notably, higher quality edges near intact forests could promote processes like dispersal and wood biomass accumulation that effectively accelerate succession, leading to better performance of shade-tolerant taxa compared to pioneer taxa in the early stages of forested plantation regeneration. This study addressed how wet tropical forested plantation regeneration was affected by distance to adjacent intact forest edge. It was hypothesized that old timber plantations facilitate regeneration by increasing available shade, favoring the presence and biomass of later-successional taxa, ultimately changing community composition overall. A wet neotropical timber plantation reforested after 20 years and adjacent to primary forest was censused for trees along a 300 m edge distance gradient, and analysis matched identified taxa to broad dispersal mode and wood density traits using relevant literature. As distance from primary forest edge increased, stem and wood density tended to increase significantly, with ~10% variation explained, while biomass and canopy light surprisingly tended to stay the same. Stand tree richness also tended to increase significantly, but diversity decreased steeply and non-linearly, explained in part by wood density, and taxonomic composition varied notably. Finally, tree taxa associated with both early and late successional stages decreased significantly, as well as genus Ficus, but biomass by dispersal mode did not tend to change. Overall this study supports that stand composition is less resilient and more subject to edge effects than biomass and richness, suggesting that global forests will likely be distinctly new assemblages in the future, with timber and biodiversity trade-offs occurring based on local and regional management activity.

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Future climate risks from stress, insects and fire across US forests

Cited by 63 publications

References 50 publications

California’s forest carbon offsets buffer pool is severely undercapitalized

California’s forest carbon offsets buffer pool is severely undercapitalized

California’s forest carbon offsets buffer pool is severely undercapitalized

Habitat edges affect tree diversity more than biomass regeneration in a reforested wet neotropical timber plantation

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