Holocene rapid climate changes and ice-rafting debris events reflected in high-resolution European charcoal records
Abstrakt
In contrast to marked climate change across glacial-interglacial cycles, the Holocene epoch represents a relatively warm, stable interval. However, on finer temporal scales, it too has experienced both gradual and rapid changes in climate.
In the North Atlantic region, many rapid climate changes (RCCs) coincide with ice-rafted debris (IRD) or Bond events, which are associated with cooling and suggested to occur with periodicities of 1370 +/- 500 years. Given that climate is a dominant control of fire activity, regulating both vegetation productivity and fuel moisture, this study investigated the linkage between Holocene fire, IRD episodes and associated RCCs in seven high-resolution charcoal records distributed across Europe.
Results show low-frequency fire periodicities of 500-600 years, 900-1400 and 2400 years that occurred simultaneously across northern and mid-latitude Europe, suggesting that regional fire disturbance responded to large-scale climate drivers. The 900-1400 year periodicity is most common among sites and of similar frequency to IRD episodes, potentially reflecting a connection between mechanisms regulating IRD flux in the North Atlantic and wildfire activity in Europe.
Although the data indicate some spatial variability in fire induced by local drivers (such as vegetation and human impact) during RCC events associated with IRD peaks, broad-scale patterns are discernible. Specifically, Northern Europe burned more during the 10.2, 9.4, 8.2, 5.9 and 4.2 kiloannum before present (ka) RCC events when climate was drier, and less during the 2.9 and 1.4 ka events when climate was moister.
In contrast, in mid-latitude Europe, a higher incidence of fire is documented at 8.2 and 1.4 ka when climate was drier and a lower incidence of fire is associated with moister conditions at 10.2, 9.4 and 2.9 ka. Spatial heterogeneity is evident in mid-latitude Europe during the 5.9, 4.2 and 0.4 ka events.
These spatially explicit sub-continental scale differences in fire activity may be related to differences in moisture availability resulting from shifts in associated atmospheric circulation patterns. (C) 2019 Elsevier Ltd. All rights reserved.