Late-Holocene moisture balance inferred from diatom and lake sediment records in western Mongolia

Abstract

The Valley of the Great Lakes in western Mongolia is a unique ecosystem comprising a wide variety of terrestrial and aquatic habitats. Relatively little is known about the long-term climate history of the area or the relative impact of changes in climate and land use in the region. Tree-ring records have established an understanding of regional temperature fluctuations; however, the few records of moisture balance from Mongolia offer little insight into potential changes in the precipitation-to-evaporation balance in the region with warming temperatures. Modern and paleoclimatic records from across arid Central Asia show substantial temporal and spatial variability in the correlation between temperature and moisture availability and climate models are inconsistent in predictions for future changes with continued warming. In order to refine the understanding of moisture balance in the region, we developed six diatom-inferred records of lake salinity between 200 and 2000 years in length, demonstrating a negative correlation between temperature and effective moisture (warm-dry and cool-wet conditions) over most of this time period. In addition to climate warming, Mongolian grasslands have seen substantial human impacts over the last several decades. Recent core records show evidence of eutrophication and must be interpreted carefully to understand the individual and combined impacts of climate and land use on sedimentary records and the potential for human—environment interactions to confound inferences about climate changes.

Pollen‐recorded bioclimatic variations of the last ~2000 years retrieved from Bayan Nuur in the western Mongolian Plateau

“…One group has been advocating the point that the climate changes in the Asian Arid Zone (AAZ) including the Mongolian Plateau have followed a 'warm-dry/cool-wet' mode (e.g. Chen et al 2010Chen et al , 2015Shinneman et al 2010;Tian et al 2013;Fallah et al 2016;Putnam et al 2016). The other group has been insisting on a 'warm-wet/cool-dry' mode (e.g.…”

Role of Surface Melt and Icing Events in Livestock Mortality across Mongolia’s Semi-Arid Landscape

“…January is the coldest month, with average temperatures ranging from −15 • C to −35 • C. Average July temperatures are much warmer, ranging from 15 • C in the mountains of the northern and western regions to between 20-25 • C at lower elevations [5]. Winter precipitation in the region is limited by the Siberian High Pressure (SHP) zone [13,32] while summer precipitation is associated with the westerlies bringing moisture from the Atlantic and Mediterranean regions [33]. However, the majority of atmospheric moisture flow to Mongolia is blocked by surrounding mountain ranges, which creates strong regional gradients in annual precipitation ranging from 300-400 mm year −1 in the western and northern regions to <100 mm year −1 in the central and southeastern areas [16].…”

“…The magnitude of pastoral vulnerability to significant dzud events is a result of the interaction between climate, rangeland management, and governance, rather than just climatic events. However, perturbations in climatic conditions are the triggers of dzud events, manifested through or enhanced by multiple mechanisms, including: 1) summer droughts [7,12]; 2) below average winter temperatures [5]; and 3) above normal snowfall [13]. Few scientific efforts have examined the role and spatiotemporal heterogeneity of the tumer dzud, defined as a significant snowmelt and subsequent icing event purported to be a major driver of livestock mortality in Mongolia [11].…”

An Estimated Contribution of Glacier Runoff to Mongolia's Upper Khovd River Basin in the Altai Mountains

“…In 2004 a United Nations water and sanitation report stated that only 30% of Mongolia's rural population had access to an ''improved'' water source, while the remaining population relied on lakes, rivers, and springs (Batbold et al 2004;Shinneman et al 2009). Within the Durgun Basin and UKRB, the quality of these natural water resources has seen significant degradation, particularly through increased salinity and eutrophication (Shinneman et al 2010), and is likely a consequence of reduced glacier runoff in sync with increased livestock grazing in riparian zones (Vorobyeva et al 2015). In addition to livestock, mining implications also contribute to the deterioration of surface water quality with increased sulfates and pH values from small-scale artisanal mining (McIntyre et al 2016).…”