[1] Understanding natural causes of climate change is vital to evaluate the relative impacts of human pollution and land surface modification on climate. We have investigated one of the most important natural causes of climate change, volcanic eruptions, by using 54 ice core records from both the Arctic and Antarctica. Our recently collected suite of ice core data, more than double the number of cores ever used before, reduces errors inherent in reconstructions based on a single or small number of cores, which enables us to obtain much higher accuracy in both detection of events and quantification of the radiative effects. We extracted volcanic deposition signals from each ice core record by applying a high-pass loess filter to the time series and examining peaks that exceed twice the 31-year running median absolute deviation. We then studied the spatial pattern of volcanic sulfate deposition on Greenland and Antarctica and combined this knowledge with a new understanding of stratospheric transport of volcanic aerosols to produce a forcing data set as a function of month, latitude, and altitude for the past 1500 years. We estimated the uncertainties associated with the choice of volcanic signal extraction criteria, ice core sulfate deposition to stratospheric loading calibration factor, and the season for the eruptions without a recorded month. We forced an energy balance climate model with this new volcanic forcing data set, together with solar and anthropogenic forcing, to simulate the large-scale temperature response. The results agree well with instrumental observations for the past 150 years and with proxy records for the entire period. Through better characterization of the natural causes of climate change, this new data set will lead to improved prediction of anthropogenic impacts on climate. The new data set of stratospheric sulfate injections from volcanic eruptions for the past 1500 years, as a function of latitude, altitude, and month, is available for download in a format suitable for forcing general circulation models of the climate system.

Volcanic Forcing of Climate over the Past 1500 Years: An Improved Ice-Core-Based Index for Climate Models

The Soils of Europe Illustrated Diagnosis and Systematics. By Prof. Dr. Walter L. Kubiena. Pp. 318 + 26 plates. (Madrid: Consejo Superior de Investigaciones Cientificas; London: Thomas Murby and Co., 1953.) n.p.

The Soils of Europe

The Eruption of Hekla, 1947-1948. Vol. 1 of The Eruptions of Hekla in Historical Times: A Tephrochronological Study. S. Thorarinsson. Leiftur, Reykjavík, 1967. 183 pp., illus. Paper, Kr. 250. A publication of Societas Scientiarum Islandica

When did the market economy come to Europe? Fish might seem an unlikely commodity to throw light on the matter, but the authors use fish bones from English sites to offer a vivid account of the rise and rise of the marketas a factor in European development from the late tenth century.

Stuart J.L. Morrison

Papers

Vestfirðir, and the Emergence of Fishing Communities in Pre-Modern Iceland