A 360 year Varve-Based Climate Reconstruction from Linnévatnet on Western Svalbard, 2009

Linnévatnet (78.05° N; 13.8° E; 12 m asl) is a proglacial lake located on the western coast of Spitsbergen, the largest island of the Svalbard archipelago. The 5.75 km² lake is set in a 35.3 km² catchment and fed by the glacier, Linnébreen, (1.7 km²) along with several small cirque glaciers. Currently, Linnébreen covers roughly 5% of the watershed in the valley of Linnédalen. The vast majority of sediment is moved into the lake during the early summer snow melt; however, particularly warm summers increase sediment transport from the landscape into the lake as the glacier continues to generate melt-water (Werner et al., 2008; McKay, 2005). Previous sedimentological studies (Pratt, 2006; Leon, 2006; Yellen, 2006; Snyder et al., 2000) have focused on sediment cores recovered from basins proximal to the inflow delta of Linnéelva in 10 to 15 meters water depth. These studies have shown that the sediments are annually laminated (varved) in these locations. Here we present results of varve thickness measurements from two sediment cores from mooring G (B1-08, B2-08) taken in the deepest basin (35 m water depth), located in the distal northerly portion of the lake. High resolution thin section analyses down both cores find that varve thickness trends are in agreement. Increasing annual varve thickness measurements show a positive correlation (r² = 0.32, 0.18 P < 0.01) with yearly historic summer (July-August) temperature measurements from a meteorological station at Isfjord Radio Station (1947-2003 AD). External forcings (solar, volcanic, etc) appear to play a key role in environmental change, especially prior (< 1850 AD) to increased anthropogenic aerosols and CO2. Despite the relatively short length, Linnévatnet’s varve record adds to the few high-resolution climate data in a region critical for understand earth’s climate system.