Editorial

Abstract

A key problem for reducing the uncertainty in future climate projections is that historical records of change are often too short to test the skill of climate models (Schmidt, 2009). Natural archives in the form of geological, chemical and biological records provide a wealth of data on past change that offer an opportunity to extend these records considerably further back in time. With the development and targeted application of improved techniques and methodologies, our understanding of the earth-climate-system has significantly improved over recent years (Jansen et al., 2007). But considerable work remains. In this issue of the Journal of Quaternary Science, we publish a fabulous range of studies that not only demonstrate how new methods are being advanced but where major inroads are continuing to be made in different regions of the world. The following are just a taster of some of the key findings in this issue.One key issue in reconstructing climate change is quantification of past temperature changes. A major challenge is that most biological proxies of climate are biased towards the growing season. Here, De Jong and Kamenik (2011) report the use of chrysophyte stomatocysts, affectionately shortened to 'cysts', to reconstruct winter temperatures. By using annually laminated sediments in Lake Silviplana, it proved possible to robustly test historical meteorological data from the Swiss Alps against cyst types. Because winter temperatures strongly control the total length of time the lake is covered in ice, an impressive correlation to temperatures was found, clearly demonstrating they have considerable potential for deriving a handle on cold-season conditions.Another recent proxy development has been in the analysis of lipid biomarkers preserved within speleothems to derive an index of vegetation cover over time. Although this approach clearly complements pollen studies, its application to areas where there is a dearth of suitable sedimentary sequences would be invaluable. Here (Blyth et al., 2011) report a fascinating study to test this approach from a 2000-year long stalagmite in northwest Scotland where the vegetation and climate history is well known. They show that this approach is remarkably successful, with many lipids preserving a clear environmental signal from the surface, supporting its application in a wide range of environments. Clearly more work is needed before this approach can be used widely but the results are extremely encouraging.Further back in time, Corrado and Magri (2011) report a record of vegetation changes from Fontana Ranuccio, an important archaeological and paleontological site of early human activity, 50 km southeast of Rome. Palaeomagnetic data imply the sequence dates to the late Early Pleistocene, most probably Marine Isotope Stage 21, during which the landscape appears to have been characterised by dense forest. Importantly, the forests at this time contained many taxa now extinct in Europe, for reasons still not clear. Furthermore, the results support the contention that ove...