Patagonia's Late Holocene lake sediments reveal no major black carbon sources for Antarctica

Abstract

Black carbon from biomass and fossil fuel burning is an important aerosol in the climate system. Understanding its historical variation is crucial to constrain current anthropogenic and wildfire impacts on the atmosphere. Patagonia was proposed previously as a major source region for the late 13^th century black carbon increase observed in an ice core from the northern Antarctic Peninsula but not in continental Antarctic ice cores. Here, we reconstruct regional black carbon trends using high-resolution measurements of refractory black carbon (rBC) in two Patagonian lake-sediment cores spanning the last two millennia and compare the results with other records of fire activity in the region. Our new rBC reconstruction, which is consistent with macroscopic charcoal data from the same sites as well as regional charcoal data, indicates low fire activity in this region of Patagonia over the past 2000 years, with no major, long-lasting and systematic increase from the 13^th century onwards that goes significantly beyond values detected earlier in these records. The consistently low rBC deposition at these sites suggests that Patagonian emissions did not contribute to the observed late 13^th century rBC increases in ice cores from the Antarctic Peninsula. Moreover, the low amounts of rBC deposition throughout the Industrial Period suggests that Patagonian rBC records primarily reflect emissions from regional biomass burning and not fossil fuel combustion.