Palynological insights into global change impacts on Arctic vegetation, fire, and pollution recorded in Central Greenland ice

Arctic environments may respond very sensitively to ongoing global change, as observed during the past decades for Arctic vegetation. Only little is known about the broad-scale impacts of early and mid 20th-century industrialization and climate change on remote Arctic environments. Palynological analyses of Greenland ice cores may provide invaluable insights into the long-term vegetation, fire, and pollution dynamics in the Arctic region. We present the first palynological record from a Central Greenland ice core (Summit Eurocore '89, 72 degrees 35'N, 37 degrees 38'W; the location of Greenland Ice Core Project GRIP) that provides novel high-resolution microfossil data on Arctic environments spanning AD 1730-1989. Our data suggest an expansion of birch woodlands after AD 1850 that was abruptly interrupted at the onset of the 20th century despite favorable climatic conditions. We therefore attribute this Betula woodland decline during the 20th century to anthropogenic activities such as sheep herding and wood collection in the sub-Arctic. First signs of coal burning activities around AD 1900 coincide with the onset of Arctic coal mining. The use of coal and fire activity increased steadily until AD 1989 resulting in microscopic-size pollution of the ice sheet. We conclude that human impact during the 20th century strongly affected (sub)-Arctic environments. Moreover, ecosystems have changed through the spread of adventive plant species (e.g. Ranunculus acris, Rumex) and the destruction of sparse native woodlands. We show for the first time that optical palynology allows paleoecological reconstructions in extremely remote sites >500 km from potential sources, if adequate methods are used.