Abstract
The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
Highlights
The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today
In Antarctica, sea ice is suggested to be the major source of sea salt aerosol[23,24,25], the relative contributions of the open ocean and sea ice are more difficult to assign for Greenland
A back-trajectory analysis performed for this study shows that the vast majority of marine air masses that potentially carry sea salt aerosol to Greenland originate from the open ocean of the North Atlantic[12]
Summary
The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. The terrestrial biogenic aerosol species NH4+ shows nearly ten times higher values for the atmospheric concentration at the source during full interglacial periods (the Eemian and the Holocene) compared to the glacial (Fig. 2) and high values during later Marine Isotope Stage (MIS) 5 warm periods (around 85 kyr before present (BP, where present is defined as 1950) and 98–106 kyr BP in the NEEM record).
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