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

Abstract

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°35’N, 37°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.

Variation of Ice Nucleating Particles in the European Arctic Over the Last Centuries

“…As a consequence, the frequency distribution broadens and follows more the shape of a log-normal distribution. Results from the pollen analysis of the EUROCORE ice core show that the two samples (spanning 12.1 and 13.6 years) with the highest concentrations of Betula alba pollen occur in the same period where some of the highest and most variable N INP (−20 • C) are observed (Brugger et al, 2019). In both ice cores we see evidence that primarily at lower temperatures the data came from a lognormally distributed population (significance level = 0.05).…”

“…Hicks and Isaksson (2006) show that birch (Betula) and juniper (Juniperus) pollen, both highly ice active, is present in ice cores from Lomonosovfonna, but the lack of temporal overlap between their and our samples hinders further comparisons. Results from the pollen analysis of the EUROCORE ice core show that the two samples (spanning 12.1 and 13.6 years) with the highest concentrations of Betula alba pollen occur in the same period where some of the highest and most variable N INP (−20 • C) are observed (Brugger et al, 2019). A further distinction between the continental biological species of the Arctic aerosol (Fu et al, 2013;Hicks & Isaksson, 2006;Moffett et al, 2015;Santl-Temkiv et al, 2018), which can also be ice active (Pummer et al, 2015), and the INP of marine origin (DeMott et al, 2016;Leck & Bigg, 2005;Schnell, 1977;Schnell & Vali, 1975, 1976Wilson et al, 2015), is not possible.…”

Climate impacts on deglaciation and vegetation dynamics since the Last Glacial Maximum at Moossee (Switzerland)

“…South of the Alps, dense boreal forests with Pinus sylvestris and Betula established in the lowlands (Vescovi et al, 2007) and tree line reached at least 1850 m a.s.l. (Tinner andVescovi, 2007, Marta et al, 2013). This rapid deglaciation in the Alps and the forest expansion in Southern and Central Europe was caused by a sudden ca.…”

“…The pollen assemblages suggest that the decline of heliophilous deciduous forests continued after 7250 cal BP (LPAZ Moos-7 to 8, 7250-6400 cal BP), when mixed beech-silver fir forests expanded massively. The general 260 prevalence of mesophilous tree species throughout LPAZ Moos-7 to LPAZ Moos-21 was likely caused by a gradual shift towards more oceanic climate conditions during the Mid-Late Holocene (Tinner andLotter 2001, 2006), as e.g. reconstructed on the basis of higher lake levels (Magny, 2013;Joannin et al, 2013).…”

Tracing devastating fires in Portugal to a snow archive in the Swiss Alps: a case study

“…These differences can be explained by dissimilar environmental conditions, as lake sediment and peat bog studies are usually performed at low-elevation sites surrounded by potential burning sources while snowpits and ice cores originate from highlatitude or high-altitude sites remote from vegetation (Brugger et al, 2018a(Brugger et al, , 2019b. These remote sites frequently lie within the free troposphere: for JFJ, free troposphere background conditions are observed about 39% of the time, with a maximum https://doi.org/10.5194/tc-2020-58 Preprint.…”