Influence of global teleconnections on Holocene climate in Kamchatka

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The study of past climate change, especially that which has occurred since the end of the last ice age about 11,000 years ago (the period known as The Holocene), provides important insights into how climate may change in the future and the influence of changes in ocean circulation and air masses. It also improves the ability of climate scientists to predict the scale and rapidity of future climate change and recognise the urgency to respond. Climate records collected at weather stations do not extend back long enough in time to capture the full extent of natural climate variability needed to be able to predict future climate change. However, it is possible to reconstruct past climate over thousands of years by studying the remains of plants and animals preserved in the mud that accumulates at the bottom of lakes. Diatoms, freshwater microscopic algae, and the larvae of non-biting midges (chironomids) respond in characteristic ways depending on summer temperatures or the relative acidity (pH) or amount of nutrients in the lake water. By finding out which temperatures, pH or nutrient concentrations are favoured by particular species of diatoms or chironomids today we can reconstruct quantitatively past environmental conditions from the semi-fossilised remains of these creatures, which are preserved in lake sediments. Thus analysis of a sediment core several metres long taken from a lake can be sliced at intervals of 1 cm or less and dated using radiocarbon to provide a highly detailed record of past climate change over thousands of years. In this project we propose to analyse midges and diatoms from three cores previously collected from Kamchatka in the far east of Russia. Kamchatka is a key region for understanding the extent of climate linkages between the North Atlantic and North Pacific regions, and hence some of the most important ways in which global climate change is driven. However, climate variability during the Holocene in this region is poorly understood as only a few studies have been completed. We will analyse midges from our three sediment cores over most of the Holocene at intervals of 40-80 years. We will use a 'midge thermometer' developed from modern distribution records of midges from throughout northern Russia, to reconstruct Holocene summer air temperatures. We will also use these midge records to reconstruct past changes in continentality or conversely oceanicity. A continental climate is governed by the relative influence of westerly winds blowing across northern Eurasia, which brings cold winters, short warm summers and less rainfall, whereas a more oceanic climate is influenced by Pacific winds which bring milder winters, cooler summers and more rain. Similarly, we will use diatoms from the same cores to quantify changes in the length of the summer and also any changes in pH or nutrients. An innovative aspect of this project will be to analyse the stable oxygen isotopes that are incorporated into the chitinous cuticle of the midge heads. Oxygen forms part of the chitin molecule and is derived from the water in which the midges are living. We expect that the ratio of stable oxygen isotopes incorporated into the midge heads will reflect the source of the water when the midge was alive. In non evaporative lakes this will tell us which air masses were driving the prevailing climate at that time (i.e. either from Eurasia or the North Pacific). By comparing our records with Holocene climate records available from other sites in the North Atlantic region, Eurasia, Alaska and the North Pacific we will be able to establish the extent of global climate links at times of different climatic regimes, for example the magnitude and timing of the Holocene Thermal Maximum and the Little Ice Age.