The natural aerosol over Northern Europe and its relation to anthropogenic emissions—implications of important climate feedbacks

We use a recently developed parametrization to estimate the regional particle field in the summer time troposphere over Scandinavia that would result if the forest were the only source of particles. The calculated field is compared with available observational data. It is concluded that the needle leaf forest above 58°N alone is capable of producing aerosol mass concentrations corresponding to 12–50% of today's values in the boundary layer over Scandinavia. We also demonstrate that the forest itself could produce up to 200 CCN per cubic centimetre on average over Scandinavia and further show that an increase in temperature by 5.8 °C compared to today's average temperature could increase this CCN population by 40%. The study shows that we are able to approximate the natural aerosol field resulting from biogenic emissions over the boreal forest in the northern hemispheric region. This information provide an important contribution in the evaluation of the climate effect caused by anthropogenic emissions of particles over the forest and also opens the possibility to better address the climate feedbacks believed to be associated with the boreal region.     

ASSESSING THE PALAEOCLIMATE POTENTIAL OF CAVE GLACIERS: THE EXAMPLE OF THE SČRIŞOARA ICE CAVE (ROMANIA)

ABSTRACT. The ice block in Scarisoara Cave, NW Romania, is preserved due to unusual climate and permafrost conditions within the cave. The air temperature in the cave is governed by the winter cold, the cooling effect of the ice block, and only to a minor extent influenced by summer temperatures. At present, the ice block is slowly thinning, but the present-day climate is sufficiently cold to preserve the permafrost conditions caused by the cold air trapped in the cave. In February 2003 a 22.5 m long ice core was recovered from the ice block. Approximately 200 ice layers have been identified by visual examination. Ice crystallographic analyses indicate a steady growth of ice crystals with depth and there is no sign of deformation. Carbon-14 dates on wood-related samples collected from a natural vertical exposure of the ice block indicate that the ice spans more than 1000 years. Observations on the exposure indicate that a basal melting phase may have occurred in the past.