Time series analyses on paleoclimatic proxy data from Icelandic lake sediments

Time series analyses on paleoclimatic proxy data from Icelandic lake sediments Collaborators: Ólafur Pétur Pálsson (http://www.hi.is/~opp), Gifford H. Miller (http://instaar.colorado.edu/people/bios/miller.html), Kristín B. Ólafsdóttir (MS student). This is the main topic of Kristín Björg Ólafsdóttir´s MS thesis (2010) RANNÍS Research Grant, University of Iceland Research Funds, Orkuveita Reykjavík, Kristín B. Ólafsdóttir, MS student at the University of Iceland (Orkuveita Reykjavikur grant & RANNÍS student grant). During the past century, global surface temperatures have increased at a rate of ~0.8°C/century, increasing to a rate of 1.8°C/century during the past 30 years. The six hottest years on record have occurred in the last eight years, with the greatest warming occurring in the Arctic. Climate models predict that the Arctic will warm by more than twice the global average in the next 100 years. Warming has already resulted in significant changes to the Arctic environment, including reduced snow cover, rapidly retreating glaciers, warmer ocean temperatures, rising sea levels, and a deepening of the active layer in the permafrost. The largest variable on decadal to centennial timescales that impacts Arctic climate is the transport of heat and moisture from lower latitudes by the ocean-atmosphere system to the Polar regions. This system accounts for approximately one third of the heat flux into in the Arctic, and is known to vary in response to changes in the Arctic Oscillation (AO) at periodicity of 10-15 years. Holocene paleoclimate proxy records also indicate high intensity for 80 and 200 years periodicities, which correspond to frequencies that characterize variations in solar luminosity. High-resolution climate records (100 to 101 yr) for the past 500 to 7000 years are available from ice cores, tree rings, and select marine and lacustrine sedimentary archives. Considerable success in combining these records for the past 500 years has enabled a detailed reconstruction of the changing modes in AO and the results reveal low-frequency cyclicity of 80 to 200 yr. However, these records do not extend far enough back in time to confirm the validity of these cycles. In order to obtain a better picture of the spatial pattern of centennial and higher frequency climate variability we have been working on available lake sediment cores from the Warm times/Cold times project that contain paleoclimatic proxy data back 12,000 years. The correlation between proxy data such as organic carbon, biogenic silica and grain size with time was analyzed. The distinction between the impact of settlement on the environment and natural climate changes was conducted by statistical methods such as time series analysis and comparison with actual climate data. Kristín B. Ólafsdóttir completed her MS thesis in Feb 2010: Time series analysis based on paleoclimatic proxies from lake sediments in Iceland.