Past fires and post-fire impacts reconstructed from a southwest Australian stalagmite

McDonough, Liza; Treble, Pauline C.; Baker, Andy; Borsato, Andrea; Frisia, Silvia; Nagra, Gurinder; Coleborn, Katie; Gagan, Michael K.; Zhao, Jianxin; Paterson, David

doi:10.1016/j.gca.2022.03.020

Cited by 15 publications

(87 citation statements)

References 90 publications

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“…Notably, stalagmite P/Ca (Fig. 1c), which reflects inputs of soil colloidal material to dripwater 15 and has been linked with enhanced fire activity in Australian stalagmites 19 , also increases at this time.…”

Section: Discussionmentioning

confidence: 92%

“…Furthermore, these proxies record a precursor event at 8300 years BP, potentially associated with an earlier pulse of freshwater from glacial Lake Agassiz 16 when precipitation exceeded the wet and dry extremes of the last 60 years in coastal California 13,15 . Thus, hydroclimatically sensitive proxies from fast-growing stalagmites can provide evidence of changes in climate whiplash, but our understanding of how wildfires may be recorded in stalagmites is just beginning to emerge [17][18][19] . New proxies are necessary to document wildfire activity to investigate the relationship between climate whiplash and wildfire in the past.…”

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confidence: 99%

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Linked fire activity and climate whiplash in California during the early Holocene

et al. 2022

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Recent wildfire activity in semi-arid regions like western North America exceeds the range of historical records. High-resolution paleoclimate archives such as stalagmites could illuminate the link between hydroclimate, vegetation change, and fire activity in pre-anthropogenic climate states beyond the timescale of existing tree-ring records. Here we present an analysis of levoglucosan, a combustion-sensitive anhydrosugar, and lignin oxidation products (LOPs) in a stalagmite, reconstructing fire activity and vegetation composition in the California Coast Range across the 8.2 kyr event. Elevated levoglucosan concentrations suggest increased fire activity while altered LOP compositions indicate a shift toward more woody vegetation during the event. These changes are concurrent with increased hydroclimate volatility as shown by carbon and calcium isotope proxies. Together, these records suggest that climate whiplash (oscillations between extreme wetness and aridity) and fire activity in California, both projected to increase with anthropogenic climate change, were tightly coupled during the early Holocene.

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Section: Discussionmentioning

confidence: 92%

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confidence: 99%

Linked fire activity and climate whiplash in California during the early Holocene

et al. 2022

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“…Brie y, all stalagmites had been actively forming at the time that they were removed from the caves and the date of removal from the cave is used as the youngest age. The chronologies for CRY-S1 37 , YD-S2 38 GL-S3 and GL-S4 26 were determined from annual laminae counting of 2D maps of Sr concentration and/or visible layering formed from fabric/colloidal matter in thin section; MND-S1 from annual laminae counting of Ba concentration from duplicate transects 39 ; LAB-S1 from the peak tting method of ref. 40 utilising principal components analysis of duplicate transects of Ba, Sr and U concentrations; while GL-S1 and GL-S2 chronologies were determined from 'bomb pulse' detection using radiocarbon analyses 41 and U/Th disequilibrium dating 26 for details of chronologies for Golgotha Cave stalagmites.…”

Section: Methodsmentioning

confidence: 99%

“…Speleothem δ 18 O. Data were previously published for all records 26,38,42 with the exception of CRY-S1 and LAB-S1. Milling and isotope ratio mass spectrometry methods are as described in ref.…”

Section: Methodsmentioning

confidence: 99%

Caves provide early warning of unprecedented decrease in rainfall recharge of groundwater

Priestley

Treble

Griffiths

et al. 2022

Preprint

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Billions of people worldwide rely on groundwater. As rainfall in many regions in the future is projected to decrease, it is critical to understand the impacts of climate change on groundwater recharge. In this study, five caves record a consistent response to a sustained decrease in rainfall across southwest Australia that began in the late 1960s, characterised by a pronounced increase or ’uptick’ in dripwater and speleothem oxygen isotopic composition (δ18O). It is demonstrated that the uptick is in response to the shallow karst aquifers becoming disconnected from recharge due to regional drying. Our findings imply that rainfall recharge to groundwater across this region is no longer reliably occurring. Examination of the longer speleothem record shows that this is unprecedented over at least the last 800 years. A global network of cave dripwater monitoring would serve as an early warning of reduced groundwater recharge elsewhere, while evidence for upticks in speleothem paleoclimate records would provide a longer-term context to evaluate if current groundwater recharge changes are outside the range of natural variability. This study also validates speleothems as recorders of past hydroclimate via amplification of the δ18O signal by karst hydrology highlighting that speleothem δ18O are records of recharge, rather than a direct proxy for rainfall.

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“…While these established fire proxy archives have been extensively used to reconstruct past fire activity, speleothems are a novel fire archive with the potential to develop high resolution, absolutely dated and relatively precise coupled climate‐fire records. This is especially relevant for regions such as southwest Australia where there are relatively few published tree ring and sediment paleofire records, but a large network of caves which have already produced stalagmites suitable for paleoclimate and paleofire research (McDonough et al., 2022).…”

Section: Typical Paleofire Archivesmentioning

confidence: 99%

A Review of Speleothems as Archives for Paleofire Proxies, With Australian Case Studies

Campbell

McDonough

Treble

et al. 2023

Reviews of Geophysics

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Wildfires are a significant hazard with ∼40% of the Earth's terrestrial surface being fire prone, and ∼3% of the terrestrial surface burning each year (Chapin et al., 2011;Giglio et al., 2010). In many areas, instances of dangerous fire weather are increasing (Jones et al., 2022). In northern California and Oregon, the likelihood of extreme autumn fire weather has increased by 40% (Hawkins et al., 2022), and both the frequency and size of wildfires have increased in the western United States (Abatzoglou & Williams, 2016;Iglesias et al., 2022). A long-term increase in both extreme fire weather and fire season length has been observed in parts of Australia (BOM and CSIRO, 2020), and there has been a global increase in the frequency of compound fire weather and meteorological drought events (Richardson et al., 2022). Fire regimes are a function of climate, human activity, and land use.

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Past fires and post-fire impacts reconstructed from a southwest Australian stalagmite

Cited by 15 publications

References 90 publications

Linked fire activity and climate whiplash in California during the early Holocene

Linked fire activity and climate whiplash in California during the early Holocene

Caves provide early warning of unprecedented decrease in rainfall recharge of groundwater

A Review of Speleothems as Archives for Paleofire Proxies, With Australian Case Studies

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