Large Scale Anthropogenic Reduction of Forest Cover in Last Glacial Maximum Europe

Abstract

Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires. Similar to hunter-gatherers of the more recent past, Upper Paleolithic humans were masters of the use of fire, and preferred inhabiting semi-open landscapes to facilitate foraging, hunting and travel. Incorporating human agency into a dynamic vegetation-fire model and simulating forest cover shows that even small increases in wildfire frequency over natural background levels resulted in large changes in the forested area of Europe, in part because trees were already stressed by low atmospheric CO2 concentrations and the cold, dry, and highly variable climate. Our results suggest that the impact of humans on the glacial landscape of Europe may be one of the earliest large-scale anthropogenic modifications of the earth system.

Impacts of surface boundary conditions on regional climate model simulations of European climate during the Last Glacial Maximum

“…Nevertheless, the more realistic distributions of temperature and precipitation by the RCM (Figures S9 and S10) clearly reflect the added value of using a high‐resolution regional climate model. Our results demonstrate the climate sensitivity to revised SSTs over the North Atlantic Ocean and to changes in boundary conditions as land use and vegetation under glacial conditions, where the latter is hypothesized to be also influenced by human activity [ Kaplan et al , ]. Thus, a realistic representation of glacial boundary conditions (SSTs and vegetation) is essential to obtain a more accurate representation of the regional (paleo‐) climate.…”

Bayesian Analysis of the Glacial‐Interglacial Methane Increase Constrained by Stable Isotopes and Earth System Modeling

“…H17 presented three alternative scenarios of LGM fire emissions: standard‐fire (simulated with a process‐based dynamic vegetation model), standard+LGM humans, which additionally incorporates an empirically based estimate of hunter‐gatherer fire activities during the LGM (Kaplan et al, ), and low fire, in which LGM fire emissions are arbitrarily set to 10% of late preindustrial values. Here preindustrial fire emissions are scaled based on ice core evidence and other modeling studies (Ferretti et al, ; Thonicke et al, ), as described in the supporting information.…”

“…Including the peatland flux leads to a stronger high-latitude source, as well as a larger reduction in total wetland/peatland emissions at the LGM of 42% versus 30% without. H17 presented three alternative scenarios of LGM fire emissions: standard-fire (simulated with a process-based dynamic vegetation model), standard+LGM humans, which additionally incorporates an empirically based estimate of hunter-gatherer fire activities during the LGM (Kaplan et al, 2016), and low fire, in which LGM fire Note. The LGM means and standard deviations are derived from the PDFs shown in the blue curves in Figure 3.…”

Bacteria in the ageing gut: did the taming of fire promote a long human lifespan?

“…Natural fires certainly shaped landscapes well before fire taming (Bowman et al ., ) and this had wide consequences, even outside the human lineage: it has been observed that birds could learn how to propagate fire by transporting embers and thus catch preys running away (Bonta et al ., ). Traces of fire have long been associated to prehistoric human artefacts (Karkanas et al ., ; Kaplan et al ., ). It is therefore accepted (Fig.…”