[MCN] It takes a while for emissions to hit the forests, but when they do, .......

Sat Jul 23 17:26:53 EDT 2022

Environmental Research Letters Published 2 December 2014
https://iopscience.iop.org/article/ <https://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002/pdf>
 <https://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002/pdf>
10.1088/1748-9326/9/12/124002/pdf <https://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002/pdf>

Maximum warming occurs about one decade after a carbon dioxide emission
Katharine L Ricke and Ken Caldeira

50,622 Total downloads
10.1088/1748-9326/9/12/124002/pdf <https://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002/pdf>

Abstract
It is known that carbon dioxide emissions cause the Earth to warm, but no previous study has focused on examining how long it takes to reach maximum warming following a particular CO2 emission. Using conjoined results of carbon-cycle and physical-climate model intercomparison projects (Taylor et al 2012, Joos et al 2013), we find the median time between an emission and maximum warming is 10.1 years, with a 90% probability range of 6.6–30.7 years. We evaluate uncertainties in timing and amount of warming, partitioning them into three contributing factors: carbon cycle, climate sensitivity and ocean thermal inertia. If uncertainty in any one factor is reduced to zero without reducing uncertainty in the other factors, the majority of overall uncertainty remains. Thus, narrowing uncertainty in century-scale warming depends on narrowing uncertainty in all contributing factors. Our results indicate that benefit from avoided climate damage from avoided CO2 emissions will be manifested within the lifetimes of people who acted to avoid that emission. While such avoidance could be expected to benefit future generations, there is potential for emissions avoidance to provide substantial benefit to current generations.

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Forest fires of the western United States have advanced upslope over the past few decades, scorching territories previously too wet to burn. We document an upslope advancement of high- elevation fires of 7.6 m/y, a rate comparable to the elevational velocity of vapor pressure deficit of 8.9 m/y. Strong interannual links between aridity and high-elevation forest fires and reduced influence of fire exclusion policies in montane mesic forests im- ply such changes are a byproduct of climate warming. We esti- mate that increased aridity between 1984 and 2017 exposed an additional 81,500 km2 of western US montane forests to fires. These changes have significant implications for terrestrial carbon storage, snowpack, and water quantity and quality. 

PNAS 2021 Vol. 118 No. 22 e2009717118
Warming enabled upslope advance in western US forest fires
https://doi.org/10.1073/pnas.2009717118  

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AGU Advances  <https://agupubs.onlinelibrary.wiley.com/journal/2576604x%22%20%5Co%20%22AGU%20Advances%20homepage%22%20%5Ct%20%22_blank>First published: 06 July 2022
Research Article
Open Access
Losses of Tree Cover in California Driven by Increasing Fire Disturbance and Climate Stress
Jonathan A. Wang <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Wang,+Jonathan+A%22%20%5Ct%20%22_blank>,James T. Randerson <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Randerson,+James+T%22%20%5Ct%20%22_blank>,Michael L. Goulden <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Goulden,+Michael+L%22%20%5Ct%20%22_blank>,Clarke A. Knight <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Knight,+Clarke+A%22%20%5Ct%20%22_blank>,John J. Battles <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Battles,+John+J%22%20%5Ct%20%22_blank>

https://doi.org/10.1029/2021AV000654 <https://doi.org/10.1029/2021AV000654%22%20%5Ct%20%22_blank>

Abstract
Forests provide natural climate solutions for sequestering carbon and mitigating climate change, yet are increasingly threatened by increasing temperature and disturbance. Understanding these threats requires accurate information on vegetation dynamics and their drivers, which is currently lacking in many regions experiencing rapid climate change such as California. To address this, we combined remote sensing observations with geospatial databases to develop annual maps of vegetation cover (tree, shrub, and herbaceous) and disturbance type (fire, harvest, and forest die-off) in California at 30 m resolution from 1985 to 2021. Considering both changes in cover fraction and areal extent, California lost 4,566 km2 of its tree cover area (6.7% relative to initial cover) since 1985. Substantial gains in tree cover area during the 1990s were more than offset by fire-driven declines since 2000, resulting in greater shrub and herbaceous cover area. Tree cover loss occurred in all ecoregions but was most severe in the southern mountains, where losses from wildfire were not compensated by regrowth in undisturbed areas. Fires and tree cover area loss generally occurred where summer temperatures were greater than 17.5°C, whereas net tree cover gain often occurred in cooler areas, suggesting that ongoing climate warming is threatening forests in many areas. California's vegetation is undergoing rapid transformation, with disturbance rates and climate change posing substantial potential risks to the integrity of California's terrestrial carbon sink.

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Forest ecosystems depend on their capacity to withstand and recover from natural and anthropogenic perturbations (that is, their resilience)1. Experimental evidence of sudden increases in tree mortality is raising concerns about variation in forest resilience2, yet little is known about how it is evolving in response to climate change. Here we integrate satellite-based vegetation indices with machine learning to show how forest resilience, quantified in terms of critical slowing down indicators3–5, has changed during the period 2000–2020. We show that tropical, arid and temperate forests are experiencing a significant decline in resilience, probably related to increased water limitations and climate variability. By contrast, boreal forests show divergent local patterns with an average increasing trend in resilience, probably benefiting from warming and CO2 fertilization, which may outweigh the adverse effects of climate change. These patterns emerge consistently in both managed and intact forests, corroborating the existence of common large-scale climate drivers. Reductions in resilience are statistically linked to abrupt declines in forest primary productivity, occurring in response to slow drifting towards a critical resilience threshold. Approximately 23% of intact undisturbed forests, corresponding to 3.32 Pg C of gross primary productivity, have already reached a critical threshold and are experiencing a further degradation in resilience. Together, these signals reveal a widespread decline in the capacity of forests to withstand perturbation that should be accounted for in the design of land-based mitigation and adaptation plans. 

Emerging signals of declining forest resilience under climate change 

Giovanni Forzieri1,5 ✉, Vasilis Dakos2, Nate G. McDowell3,4, Alkama Ramdane1 & Alessandro Cescatti1

Nature Published online July 13, 2022 

https://doi.org/10.1038/s41586-022-04959-9 

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“By the end of the 21st century, forest ecosystems in the United States will differ from those of today as a result of changing climate.”

Effects of climatic variability and change on forest ecosystems: a comprehensive science synthesis for the U.S. 
General Technical Report PNW-GTR-870. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 265 p. Vose, James M.; Peterson, David L.; Patel-Weynand, Toral. 2012. 

http://treesearch.fs.fed.us/pubs/42610

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Alaska Is Headed for an Epic Fire Season - Mother Jones <https://www.motherjones.com/environment/2022/07/alaska-fires-epic-season-2022-lightning-drought/>
https://www.motherjones.com › environment › 2022/07 <https://www.motherjones.com/environment/2022/07/alaska-fires-epic-season-2022-lightning-drought/>

Jul 9, 2022 — Faced with the challenge of adapting to a future of fire in the Arctic, ...

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“Whereas any one line of evidence may be weak in itself, a number of lines of evidence, taken together and found to be consistent, reinforce one another exponentially.”

Preston Cloud and Aharon Gibor. The Oxygen Cycle. 
Scientific American, September 1970

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