Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core

Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales spanning millennia, and are thus use- ful to examine the role of fire in the carbon cycle and climate system. Here we use the specific biomarker levo- glucosan together with black carbon and ammonium concen- trations from the North Greenland Eemian (NEEM) ice cores ◦◦ (77.49 N, 51.2 W; 2480ma.s.l) over the past 2000 years to infer changes in boreal fire activity. Increases in boreal fire activity over the periods 1000–1300 CE and decreases during 700–900 CE coincide with high-latitude NH temper- ature changes. Levoglucosan concentrations in the NEEM ice cores peak between 1500 and 1700 CE, and most levo- glucosan spikes coincide with the most extensive central and northern Asian droughts of the past millennium. Many of these multi-annual droughts are caused by Asian mon- soon failures, thus suggesting a connection between low- and high-latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative prox- imity to the Greenland Ice Cap. During major fire events, however, isotopic analyses of dust, back trajectories and links with levoglucosan peaks and regional drought reconstruc- tions suggest that Siberia is also an important source of py- rogenic aerosols to Greenland.