Boreal fire records in Northern Hemisphere ice cores: a review

Abstract

Abstract. Here, we review different attempts made since the early 1990s to reconstruct past forest fire activity using chemical signals recorded in ice cores extracted from the Greenland ice sheet and a few mid-northern latitude, high-elevation glaciers. We first examined the quality of various inorganic (ammonium, nitrate, potassium) and organic (black carbon, various organic carbon compounds including levoglucosan and numerous carboxylic acids) species proposed as fire proxies in ice, particularly in Greenland. We discuss limitations in their use during recent vs. preindustrial times, atmospheric lifetimes, and the relative importance of other non-biomass-burning sources. Different high-resolution records from several Greenland drill sites and covering various timescales, including the last century and Holocene, are discussed. We explore the extent to which atmospheric transport can modulate the record of boreal fires from Canada as recorded in Greenland ice. Ammonium, organic fractions (black and organic carbon), and specific organic compounds such as formate and vanillic acid are found to be good proxies for tracing past boreal fires in Greenland ice. We show that use of other species -potassium, nitrate, and carboxylates (except formate) -is complicated by either post-depositional effects or existence of large non-biomassburning sources. The quality of levoglucosan with respect to other proxies is not addressed here because of a lack of highresolution profiles for this species, preventing a fair comparison. Several Greenland ice records of ammonium consistently indicate changing fire activity in Canada in response to past climatic conditions that occurred during the last millennium and since the last large climatic transition. Based on this review, we make recommendations for further study to increase reliability of the reconstructed history of forest fires occurring in a given region.

Holocene black carbon in Antarctica paralleled Southern Hemisphere climate

“…The eastern Amazonia charcoal results are also broadly consistent with the proximal Illimani ice core record. The Illimani ice core record of NH 4 + spanning the last 1500 years from the tropical Bolivian Andes (Figure 7d, location shown in Figure 1) is a proximal ice core record originally interpreted primarily as a proxy of Amazonian temperature [Eichler et al, 2009;Kellerhals et al, 2010] rather than more traditionally as a proxy of biomass burning [Legrand et al, 2016]. Given the decadal-tocentury scale agreement with the BC and NH 4 + records from the B40 ice core, we suggest that the Illimani ice core NH 4 + record also reflects a reduction in BB during the LIA (Figure 7).…”

Historic global biomass burning emissions for CMIP6 (BB4CMIP) based on merging satellite observations with proxies and fire models (1750–2015)

“…Therefore, the original SPITFIRE model was integrated into LPJ-GUESS (Smith et al, 2001) and was adapted to take advantage of these features. Most importantly, the fire characteristics are calculated separately for each patch and the burned area for a patch is interpreted as the probability of a particular patch burning, rather than as a fraction of the locality that burns (Lehsten et al, 2009). As a further consequence of the more detailed vegetation structure, the size-dependent mortality functions in SPITFIRE have a more realistic impact, whereby small trees have a relatively higher probability of being killed by fires than large trees.…”

“…Excess ammonium in ice cores has been used as a fire proxy on very long timescales (Fischer et al, 2015), and in rare cases multi-proxy fire reconstructions have also been developed from ice cores (Eichler et al, 2011;Legrand et al, 2016).…”

Historical black carbon deposition in the Canadian High Arctic: A 190-year long ice-core record from Devon Island

“…Aerosol species such as K + or NH4 + are commonly associated with BB emissions, and as such are often used as BB tracers in polar snow (Simoneit, 2002;Legrand et al, 2016). Cheng (2014) …”