The Arctic is an important geographic region undergoing rapid temperature rise. Because of “Arctic amplification”, temperature increases currently are among the highest on Earth and are driving important climate-ecosystem feedback mechanisms that have both regional and global effects. Microfossil impurities (e.g. microcharcoal particles) in pure surface snow on the Greenland ice sheet not only directly change the surface albedo but they also are incorporated into layers of snow and ice thereby preserving records of past changes in microfossil concentrations over millennia. Recent analytical advances allow extraction of these microfossils from polar ice cores in sufficient numbers to achieve continuous records of past environmental dynamics and to address ecological questions. Such palynological analyses may provide valuable insights into the long-term vegetation, fire, and pollution dynamics in the Arctic region on a large spatial scale. We use optical analyses of pollen and spores in ice cores as a proxy for past vegetation composition and land use, microscopic charcoal to infer biomass burning, and soot (or SCP =spheroidal carbonaceous particles) as a specific tracer to reconstruct fossil fuel burning. The records are from an array of ice cores including sites in southern, central, and northern Greenland that span the past millennium with continuous sampling at decadal resolution.
Results/Conclusions
Our preliminary data suggest expansion of birch woodlands after AD 1850 that abruptly ended at the beginning of the 20th century despite warmer climatic conditions at the end of the Little Ice Age. We link the birch woodland decline to human activities such as sheep herding and timber gathering in the sub-Arctic. The first signs of coal burning pollution (beginning of SCP record) around AD 1900 coincide with the onset of Arctic coal mining activities and sensitive Arctic ecosystems were further altered through the spread of adventive plant species (e.g. Ranunculus acris-type and Rumex) probably introduced by Medieval Norse settlers in Southern Greenland. We show for the first time that if suitable methods are applied, optical palynology allows paleoecological reconstructions in these unique and extremely remote ice-core sites located hundreds of kilometers from potential microfossil sources. Our study provides fundamental knowledge that advances the interpretation of remote palynological records with large catchments in different geographical regions such as high-alpine records in the mid-latitudes and the tropics, as well as potential future studies in Antarctica.