Dust flux estimates for the Last Glacial Period in East Central Europe based on terrestrial records of loess deposits: a review

Abstract

Loess–paleosol sequences are significant records of the mineral dust cycle of glacial–interglacial periods. As dust particles give rise to direct and indirect radiative forcing, obtaining a reliable picture of the global and regional patterns of mineral dust fluxes during glacial periods can lead to a better understanding of the contribution of mineral dust to past climate changes. Recent progress in absolute dating of loess deposits in the Carpathian Basin in East Central Europe made it possible to provide correct aeolian flux estimates for the Last Glacial period, marine isotope stage (MIS) 2. Mass accumulation rates (MARs) from chronological data of 33 loess sites exhibited a wide range of values, from 150 to 1422 g m −2 a −1, centered around median and mean values of 338 and 417 g m −2 a −1. MAR PM 10 and MAR PM 2 estimates have been also calculated using grain size measurements of many loess samples and loess MARs in order to facilitate comparison with models, and since particles larger than 10 μm have a negligible radiative effect. Here we show that some previous model simulations of the dust cycle at the Last Glacial Maximum (LGM) significantly underestimated the real aeolian flux (ranges of our estimates: MAR PM 10 = 34 − 324 and MAR PM 2 = 9.3 − 88.2 g m − 2 a − 1 ) in East Central Europe. For this reason, some simulations of dust-induced direct radiative forcing of the LGM climate failed to yield reliable results for this mid-latitude region as they have been based on three-dimensional dust field models that are not capable of estimating the real aeolian fluxes in Central Europe. A recent global model of top of the atmosphere (TOA) radiative forcing by mineral aerosols at the LGM that has been based on more realistic parameterization of dust sources, transport, and deposition revealed zonally averaged surface cooling of −2 °C for the latitudes of our study area. This surface cooling and TOA radiative forcing (−2 to −3 W m −2) are greater than recognized in other models and draws our attention to the importance of further modeling the impact of mineral dust on LGM climate in order to gain insight into the spatial pattern of radiative forcing and better understand resulting climate response in mid-latitude loess regions such as East Central Europe.