Influence of global teleconnections on Holocene climate in Kamchatka

对过去气候变化的研究，特别是对大约11,000年前最后一个冰河时代结束以来发生的气候变化的研究，为未来气候如何变化以及海洋环流和空气质量变化的影响提供了重要的见解。它还提高了气候科学家预测未来气候变化的规模和速度的能力，并认识到应对的紧迫性。气象站收集的气候记录没有足够长的时间来捕捉自然气候变化的全部程度，从而能够预测未来的气候变化。然而，通过研究湖底堆积的淤泥中保存的动植物遗骸，有可能重建数千年来的过去气候。硅藻、淡水微型藻类和非叮咬性摇蚊幼虫（摇蚊）的反应方式取决于夏季温度或湖水中的相对酸度（pH值）或营养物质的量。通过找出今天特定种类的硅藻或摇蚊喜欢的温度、pH值或营养浓度，我们可以从这些生物的半化石遗迹中定量重建过去的环境条件，这些生物保存在湖泊沉积物中。因此，对取自湖泊的几米长的沉积物岩芯的分析可以以1厘米或更小的间隔进行切片，并使用放射性碳测定年代，以提供数千年来过去气候变化的非常详细的记录。在这个项目中，我们建议分析蠓和硅藻从三个核心以前收集的堪察加半岛在俄罗斯远东地区。堪察加半岛是了解北大西洋和北太平洋地区之间气候联系程度的关键地区，因此也是推动全球气候变化的一些最重要方式。然而，该地区全新世的气候变率知之甚少，因为只有少数研究已经完成。我们将分析蠓从我们的三个沉积物岩心在全新世的大部分时间间隔为40-80年。我们将使用一个“蠓温度计”，从整个北方俄罗斯的现代分布记录，重建全新世夏季气温。我们还将利用这些蚊记录来重建过去的大陆性变化或相反的海洋性变化。大陆性气候受吹过欧亚大陆北方的西风的相对影响，这带来了寒冷的冬天，短暂的温暖的夏天和较少的降雨，而更多的海洋性气候受太平洋风的影响，带来了温和的冬天，凉爽的夏天和更多的降雨。同样，我们将使用来自相同核心的硅藻来量化夏季长度的变化以及pH值或营养物质的任何变化。该项目的一个创新方面将是分析纳入吸浆虫头部几丁质角质层的稳定氧同位素。氧气是甲壳素分子的一部分，来源于蠓生活的水中。我们预计，吸浆虫头部的稳定氧同位素比例将反映吸浆虫存活时的水源。在非蒸发性湖泊中，这将告诉我们当时是哪些气团驱动了主导气候（即来自欧亚大陆或北太平洋）。通过将我们的记录与北大西洋地区、欧亚大陆、阿拉斯加和北太平洋其他地点的全新世气候记录进行比较，我们将能够确定不同气候状态下全球气候联系的程度，例如全新世最大热期和小冰期的大小和时间。

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.