The Elbrus (Caucasus, Russia) ice core record – Part 2: history of desert dust deposition

oleh: S. Kutuzov, M. Legrand, M. Legrand, S. Preunkert, S. Preunkert, P. Ginot, P. Ginot, P. Ginot, V. Mikhalenko, K. Shukurov, A. Poliukhov, A. Poliukhov, P. Toropov, P. Toropov

Format: Article
Diterbitkan: Copernicus Publications 2019-11-01

Deskripsi

<p>Ice cores are one of the most valuable paleo-archives. Records from ice cores provide information not only about the amount of dust in the atmosphere, but also about dust sources and their changes in the past. In 2009, a 182&thinsp;m long ice core was recovered from the western plateau of Mt Elbrus (5115&thinsp;m&thinsp;a.s.l.). This record was further extended after a shallow ice core was drilled in 2013. Here we analyse <span class="inline-formula">Ca<sup>2+</sup></span> concentrations, a commonly used proxy of dust, recorded in these Elbrus ice records over the time period of 1774–2013&thinsp;CE. The <span class="inline-formula">Ca<sup>2+</sup></span> record reveals quasi-decadal variability with a generally increasing trend. Using multiple regression analysis, we found a statistically significant spatial correlation of the Elbrus <span class="inline-formula">Ca<sup>2+</sup></span> summer concentrations with precipitation and soil moisture content in the Levant region (specifically Syria and Iraq). The <span class="inline-formula">Ca<sup>2+</sup></span> record also correlates with drought indices in North Africa (<span class="inline-formula"><i>r</i>=0.67</span>, <span class="inline-formula"><i>p</i><i>&lt;</i>0.001</span>) and Middle East regions (<span class="inline-formula"><i>r</i>=0.71</span>, <span class="inline-formula"><i>p</i><i>&lt;</i>0.001</span>). Dust concentrations prominently increase in the ice core over the past 200 years, confirming that the recent droughts in the Fertile Crescent (1998–2012&thinsp;CE) present the most severe aridity experienced in at least the past two centuries. For the most recent 33 years recorded (1979–2012&thinsp;CE), significant correlations exist between <span class="inline-formula">Ca<sup>2+</sup></span> and Pacific circulation indices (Pacific Decadal Oscillation, Southern Oscillation Index and Niño 4), which suggests that the increased frequency of extreme El Niño and La Niña events due to a warming climate has extended their influence to the Middle East. Evidence demonstrates that the increase in <span class="inline-formula">Ca<sup>2+</sup></span> concentration in the ice core cannot be attributed to human activities, such as coal combustion and cement production.</p>