Line 1: Polar ice core and paleoclimate research
►Quaternary paleoclimate reconstructions through production of precise stratigraphic records of dust concentration, flux and grain size that are used as benchmark for many other paleoclimate proxies.
the leading contribution of UNIMIB to the EPICA (European Project for Ice Coring in Antarctica) project has allowed to gain experience in dust analysis and data treatment. in particular, the climate and environmental changes occurred during the last 800.000 years have been deeply investigated as well as the dust-climate coupling on orbital timescales. In addition, dust grain size analysis has been used to study the past atmospheric circulation changes, and the role of seasonality in dust transport.
Other dust studies on peripheral cores located at the margin of the Antarctic plateau, like TALDICE (Talos Dome Ice Core Drilling Project) allowed a detailed reconstruction of the deglaciation history of the Ross Sea, and a comparison with hemispheric and global climate changes.
EUROCOLD Lab is now deeply implicated in the study of processes affecting the deeper part of ice cores, that is of particular interest to the “Beyond EPICA-Oldest Ice” scientific community.
►Development of multi-parametric approaches to dust source tracking
Dust provenance studies are essential to understand atmospheric dynamics in the past. in this respect, at EUROCOLD we developed different approaches for dust source investigation, in collaboration with many Italian and European laboratories. the sr-nd isotopic composition (87sr/86sr , 143nd/144nd) of samples, accompanied by the analysis of major and trace elements by INAA (instrumental neutron activation analysis) and by single-grain mineralogical studies (Raman spectroscopy), elemental coordination for sources comparisons (Synchrotron Light, collaboration with INFN), offer crucial information about parent rocks and conditions under which the parent material formed.
in parallel with mineral dust extracted from ice cores, many sediment samples from different dust sources distributed all over the world, but especially in Antarctica and in the Southern Hemisphere are stored and available for analysis.
► in collaboration with University of Milan (M. Potenza) some novel optical techniques aimed are being developed at EUROCOLD to better constrain the optical properties of dust and its direct effect on climate.
►in collaboration with ENEA-Rome (B.Narcisi) activities related to identification of the sources for tephra and cryptotephras are being developed.
►in collaboration with the University of Urbino (L.Lanci) magnetic studies on ice cores are ongoing in order to assess both the extraterrestrial contribution to the dust influx in polar region and to investigate the iron oxides contained in Antarctic the dust.
Line 2 : Non-polar ice archives.
►European Alps, as for the other mid-latitude mountain chains as the Himalaya-Karakorum or Tien Shan Mnt., represent one pf the most important archive of environmental an climates information as well as of human impacts. Reconstruction of the mineral dust transport form the North Africa toward the Europe, impact of the radiogenic elements on the Alpine chain, and reconstruction of the vegetation history by pollen and eDNA barcoding methods. Drilling activities will be done with the EUROCOLD Lab facilities, permitting the recovering of ice core from cold and temperate glaciers, and open collaboration with many Italian and international partners (INFN, CNR, ENEA, i.e.).
►Underground ice glaciers, stored in caves, represent the novel frontiers of the glaciological research, because the ice caves are present at latitude and altitude below the normal glacier conditions. Also, in areas where the glaciers are disappeared the ice caves preserve ice deposits. That permit to use glaciological methodology (i.e. ice core) to recovery samples approaching with glaciological studies. The work is done in Italy, Romania, Germany, Austria, Slovenia, Slovak Republic, USA and China, in collaboration with the International Speleological Union, and the main karstological institutes. That permit to improve the geographical distribution of the “frozen archives” and find climatic and environmental data in non-glaciated areas.
Line 3: Climate and paleoclimate modelling including mineral dust cycle
Mineral (desert) dust is the most abundant aerosol by mass in the atmosphere, alone contributing about a quarter of the total sunlight extinction by atmospheric aerosols, natural and anthropogenic. Dust acts both as a tracer and a forcing agent of climate change. Past dust variability, imprinted in paleodust records from natural archives, offers the unique opportunity to reconstruct the global dust cycle within a range of possibilities that plausibly encompass future variations in response to climate change and land cover and land use changes. Dust itself has direct and indirect feedbacks on the climate system, through impacts on the atmosphere radiative budget and the carbon cycle.
The deserts in western and northern China are major global dust sources with relevance for the mid- and high latitudes of the Northern Hemisphere. The most stunning evidence of eastern Asian dust history in the Quaternary and beyond in response to orbital forcing lies in the thick deposits of the Chinese Loess Plateau (CLP), which covers extremely vast areas of the upper and middle reaches of the Yellow River to the southeast of the Badain Juran, Tengger, and Ordos deserts. In fact loess is a terrestrial deposit of eolian origin, formed by the resuspension and eventually the re-deposition of dust particles, whose origin can be ultimately tracked back to glacial and fluvial erosion.
Dust particle size distributions are a key variable for the interpretation of loess/paleosol records, also in the context of regional stratigraphic models. The interpretation of dust mass accumulation rates is intimately linked to particle size distributions. Gravitational settling, but also dry (turbulent) and wet deposition, exert a control on deposited particle size distribution, and in turn cause a shift in the size distributions of airborne dust particles, with implications for direct and indirect radiative effects.
Our knowledge would greatly benefit from the establishment of an observational network allowing us to partition dust deposition fluxes and particle size distributions between dry and wet deposition processes. Ideal locations include existing meteorological and air quality stations (providing data such as temperature, precipitation, wind speed and direction, PM2.5, PM10, TSP), that are located in close proximity to known or suitable sites for the study of loess/paleosol sections in China. It would also be beneficial to have data along transects between a section of interest and the putative source areas for dust, in order to consistently track the spatial evolution of dust deposition rates and particle size distributions.
In addition to directly help the interpretation of loess/paleosol sections, such a novel dataset would provide an exceptional observational constraint for model simulation of the dust cycle, embedded in regional and global Earth System Models. Those models can in turn be used for paleoclimate simulations, providing yet additional elements to help the interpretation of paleodust records, but also for testing the physical parameterizations of ESMs that are used for future climate projections.