"Warm Times, Cold Times:-Quantitative Reconstructions of Near-Shore Environments Over the Last 2000 Years in Vestfirdir, NW Iceland: Natural Changes and Human Responses

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

ABSTRACT Andrews OPP-0327187 A better understanding of future environmental change is a pressing need of human society today and projections can be tested and evaluated by reconstructing the ranges and rates of past changes. The goal of this project is to develop a quantitative reconstruction of the marine climate Vestfirdir, north Iceland over the last 2000 years. Northern Iceland was chosen because of its sensitive location. This small area encapsulates climatic changes throughout much of the North Atlantic because it lies at the boundary between the Atlantic and Polar/Arctic realms, which drive much of the change. In addition, this is ideal area for climate reconstruction because it has 1) an extensive database of modern instrumental climate data, 2) a 1,200 year historical documentary climate record, and 3) well dated, high-resolution sediment cores containing an archive of natural climate variability. The research will reconstruct seasonal and annual temperature variations based on the stable isotopic composition of marine molluscs from three marine cores in Vestfirdir. The isotope data will be calibrated against the modern instrumental record and applied to molluscs in the cores. Seasonal to annual temperature estimates will be achieved through analysis of 60 individuals, with life spans of two to ten years, that lived during modern times, through the Settlement of Iceland (AD 871) and beyond the interval of human impact to c. 2000 years ago. The use of the micromilled molluscs in marine cores is the only way, at present to obtain seasonally- to-annually resolved climate data from Iceland, beyond the instrumental and documentary record. The short, but annually resolved records are placed within an environmental framework through analysis of other traditional proxy records. Drawing on earlier analyses of these cores, major environmental changes of the past are identified. These include a prolonged "cold" interval between 70 and 400 yr B.P. (ca. AD 1930 back to 1600), an interval with lower ?18O (CaCO3) (warmer) values around AD 1000, and a cool interval centered at AD 670. The project will select molluscs for analysis within these .warm. and .cold. intervals. In order to study the human dimensions of these changes, emphasis will be placed on the period from the Settlement of Iceland (c. AD 871) to the present. Isotope-based temperature reconstructions will be used to evaluate historical records of Icelandic sea-ice incidence and fisheries catches, with the main goals of: 1) determining the role of oceanic variability in the productivity of Icelandic fisheries; and 2) isolating periods when non-climatic factors might have played a role in fisheries variations. The impact of the reconstructed marine climates on biodiversity will be measured by changes in benthic foraminiferal assemblages. Broader Impacts This project represents a multidisciplinary evaluation and analysis of the role of climate change on the nearshore marine climate and its association with changes in historical fisheries practices and catches. It represents an international effort, with researchers from the USA and Canada and with co-operation from several colleagues in Iceland. It also fosters collaboration between NSF and Rannis (the Icelandic Science Foundation). Links with the archeological community currently working on the zooarcheology of sites in northern Iceland will be strengthened. This collaboration will enable analysis of stable isotopes on fish otoliths found in the refuse from these sites and comparison of these variations with the stable isotope data from the marine cores. The project will educate both graduate and undergraduate students, and will be beneficial in the training of young scientists in geochemical methods and micro- and macro -paleontology.