251 research outputs found
Testing the Hypothesis of Fire Use for Ecosystem Management by Neanderthal and Upper Palaeolithic Modern Human Populations
BACKGROUND: It has been proposed that a greater control and more extensive use of fire was one of the behavioral innovations that emerged in Africa among early Modern Humans, favouring their spread throughout the world and determining their eventual evolutionary success. We would expect, if extensive fire use for ecosystem management were a component of the modern human technical and cognitive package, as suggested for Australia, to find major disturbances in the natural biomass burning variability associated with the colonisation of Europe by Modern Humans. METHODOLOGY/PRINCIPAL FINDINGS: Analyses of microcharcoal preserved in two deep-sea cores located off Iberia and France were used to reconstruct changes in biomass burning between 70 and 10 kyr cal BP. Results indicate that fire regime follows the Dansgaard-Oeschger climatic variability and its impacts on fuel load. No major disturbance in natural fire regime variability is observed at the time of the arrival of Modern Humans in Europe or during the remainder of the Upper Palaeolithic (40-10 kyr cal BP). CONCLUSIONS/SIGNIFICANCE: Results indicate that either Neanderthals and Modern humans did not influence fire regime or that, if they did, their respective influence was comparable at a regional scale, and not as pronounced as that observed in the biomass burning history of Southeast Asia
A first look at the ACER-SST dataset: Mapping the spatio-temporal variability of sea-surface temperatures in the last Glacial and the Holocene
The ACER pollen and charcoal database: a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
Quaternary records provide an opportunity to examine the nature of the
vegetation and fire responses to rapid past climate changes comparable in
velocity and magnitude to those expected in the 21st-century. The best
documented examples of rapid climate change in the past are the warming events
associated with the DansgaardâOeschger (DâO) cycles during the last glacial
period, which were sufficiently large to have had a potential feedback through
changes in albedo and greenhouse gas emissions on climate. Previous
reconstructions of vegetation and fire changes during the DâO cycles used
independently constructed age models, making it difficult to compare the
changes between different sites and regions. Here, we present the ACER (Abrupt
Climate Changes and Environmental Responses) global database, which includes
93 pollen records from the last glacial period (73â15âŻka) with a temporal
resolution better than 1000âŻyears, 32 of which also provide charcoal records.
A harmonized and consistent chronology based on radiometric dating (14C,
234Uâ230Th, optically stimulated luminescence (OSL), 40Arâ39Ar-dated tephra
layers) has been constructed for 86 of these records, although in some cases
additional information was derived using common control points based on event
stratigraphy. The ACER database compiles metadata including geospatial and
dating information, pollen and charcoal counts, and pollen percentages of the
characteristic biomes and is archived in Microsoft AccessTM at
https://doi.org/10.1594/PANGAEA.870867
The Reading Palaeofire Database : an expanded global resource to document changes in fire regimes from sedimentary charcoal records
Sedimentary charcoal records are widely used to reconstruct regional changes in fire regimes through time in the geological past. Existing global compilations are not geographically comprehensive and do not provide consistent metadata for all sites. Furthermore, the age models provided for these records are not harmonised and many are based on older calibrations of the radiocarbon ages. These issues limit the use of existing compilations for research into past fire regimes. Here, we present an expanded database of charcoal records, accompanied by new age models based on recalibration of radiocarbon ages using IntCal20 and Bayesian age-modelling software. We document the structure and contents of the database, the construction of the age models, and the quality control measures applied. We also record the expansion of geographical coverage relative to previous charcoal compilations and the expansion of metadata that can be used to inform analyses. This first version of the Reading Palaeofire Database contains 1676 records (entities) from 1480 sites worldwide. The database (RPDv1b - Harrison et al., 2021) is available at https://doi.org/10.17864/1947.000345.Peer reviewe
Assessing changes in global fire regimes
PAGES, Past Global Changes, is funded by the Swiss Academy of Sciences and the Chinese Academy of Sciences and supported in kind by the University of Bern, Switzerland. Financial support was provided by the U.S. National Science Foundation award numbers 1916565, EAR-2011439, and EAR-2012123. Additional support was provided by the Utah Department of Natural Resources Watershed Restoration Initiative. SSS was supported by Brigham Young University Graduate Studies. MS was supported by National Science Centre, Poland (grant no. 2018/31/B/ST10/02498 and 2021/41/B/ST10/00060). JCA was supported by the European Unionâs Horizon 2020 research and innovation program under the Marie SkĆodowska-Curie grant agreement No 101026211. PF contributed within the framework of the FCT-funded project no. UIDB/04033/2020. SGAF acknowledges support from Trond Mohn Stiftelse (TMS) and University of Bergen for the startup grant âTMS2022STG03â. JMP participation in this research was supported by the Forest Research Centre, a research unit funded by Fundação para a CiĂȘncia e a Tecnologia I.P. (FCT), Portugal (UIDB/00239/2020). A.-LD acknowledge PAGES, PICS CNRS 06484 project, CNRS-INSU, RĂ©gion Nouvelle-Aquitaine, University of Bordeaux DRI and INQUA for workshop support.Background The global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300. Results Respondents indicated some direct human influence on wildfire since at leastâ~â12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios. Conclusion The influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.Peer reviewe
Variabilité des incendies en Europe de l'Ouest au cours du dernier cycle climatique: relations avec le climat et les populations paléolithiques. Etude des microcharbons préservés dans les carottes marines
Fire regime of the last climatic cycle of Western Europe has been documented by analysing microcharcoal preserved in two cores collected off southwestern Iberia and Western France. Automated image analysis using transmitted light of microcharcoal particles combined with petrographic analysis have revealed a millennial variability of the fire regime, characterised by higher regime during interstadials (warmings) than during stadials (coolings). This variability has been related to biomass and fuel load, in particular in Iberia with alternation of Mediterranean forest-heathlands (interstadials) and semi-desert vegetation (stadials). Three phases of fire regime in Western France have been observed during Heinrich events, related to biomass and environmental condition changes. The comparison between fire regime of Western Europe and Paleolithic occupations suggest that fire was not extensively used for ecosystem management by modern humans at the time of their arrival in this region.Le rĂ©gime des feux du dernier cycle climatique en Europe de l'Ouest a Ă©tĂ© Ă©tudiĂ© en analysant les microcharbons prĂ©servĂ©s dans deux carottes prĂ©levĂ©es sur les marges du sudouest ibĂ©rique et de l'Ouest de la France. L'analyse d'image automatique Ă lumiĂšre transmise des microcharbons combinĂ©e Ă une analyse pĂ©trographique a rĂ©vĂ©lĂ© une variabilitĂ© millĂ©naire dans le rĂ©gime des feux, caractĂ©risĂ©e par un rĂ©gime plus Ă©levĂ© pendant les interstadiaires (rĂ©chauffements) que pendant les stadiaires (refroidissements). Cette variabilitĂ© a Ă©tĂ© mise en relation avec la biomasse et la quantitĂ© de combustible, en particulier en IbĂ©rie avec l'alternance de forĂȘt mĂ©diterranĂ©enne-bruyĂšres (interstadiaires) et de vĂ©gĂ©tation semidĂ©sertique (stadiaires). Trois phases du rĂ©gime des feux de l'Ouest de la France ont Ă©tĂ© dĂ©tectĂ©es au cours des Ă©vĂšnements d'Heinrich, reliĂ©s Ă des changements de biomasse et de conditions environnementales. La comparaison du rĂ©gime des feux de l'Ouest de l'Europe avec les occupations humaines PalĂ©olithiques suggĂšre que l'homme moderne n'a pas utilisĂ© le feu de maniĂšre intensive comme outil d'amĂ©nagement de son territoire lors de son arrivĂ©e dans cette rĂ©gion
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