2000 years of annually resolved hydroclimatic changes at Linnevatnet Lake, Svalbard

Abstract:

Understanding the impacts of climate change require collection and analysis of high-resolution data from climate archives in the most sensitive regions. Svalbard is located at the forefront of sea-ice changes in the Arctic, making this location ideal for paleoclimatic research. Here, annually resolved grain-size and µ-XRF data were extracted for the past 2000 years from cores collected from Lake Linnevatnet. During the instrumental era, our record is correlated to annual temperature and precipitation over the last ~120 years (r = 0.50, p < 0.001). Over the past millennium, a strong co-variability is found with the coupled climate model ECHO-G Northern Hemisphere temperature (r = 0.42, n = 990, p < 0.001), suggesting that our sedimentary archive captures well large-scale temperature variability. Before the first millennium, relatively stable temperature changes are observed from 5 BC to ~1000 CE. Thereafter, higher frequency variability dominates the record with a decrease in temperature starting around 1200 CE, followed by a progressive decline that culminated in the early 18^th century. This climatic pattern is coherent with an annually-resolved winter temperature (∂¹⁸O) from the Lomonosovfonna Ice Cap (Divine et al. 2011), located ~120 km North-East from Linnevatnet Lake (r = 0.36, n = 1100, p < 0.001). Although records from the ice cap end in 1997, their temperature reconstruction suggests that the Medieval period before the 1200s was at least as warm as at the end of the 1990s in Svalbard. Our record also depicts similarly warm periods before 1200s; however, our sedimentary archive indicates that the recent period is now the warmest of the past ~2000 years. In the sediment trap collected since 2005, layers enriched in Calcium consistently coincided with periods of elevated rainfall measured at the weather station from the site. The coarsest grains and the sharpest increased in Calcium occurred in 2016, a year that was characterized by unprecedented amounts of rainfall since instrumental measurements began, suggesting a recent hydrological shift in Svalbard in the context of the past two millennia.

Divine et al (2011). Thousand years of winter surface air temperature variations in Svalbard and northern Norway reconstructed from ice core data. Polar Research.