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Section 2: Climate Change and Hydrology

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https://hdl.handle.net/10217/195527

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Browsing Section 2: Climate Change and Hydrology by Subject "drought"

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    How unusual was the 21st century drought in Mongolia?: placing recent extremes in an 1100-year context
    (Colorado State University. Libraries, 2015-06) Hessl, Amy E., author; Pederson, Neil, author; Byambasuran, Oyunsanaa, author; Anchukaitis, Kevin, author; Leland, Caroline, author; Nutag Action and Research Institute, publisher
    Understanding the connections between climate, ecosystems, and society during historical and modern climate transitions requires annual resolution records with high fidelity climate signals. In the 21st century, Mongolia experienced a rapid transition away from pastoralism as many families lost their herds during a drought and severe winter conditions (dzuds). Though the drivers of this transition were likely multi-factorial, many blamed market forces and overgrazing by herders. Because Mongolia's climate is highly variable, it is difficult to place recent climatic extremes and associated social change in context without long records of climatic variability. Here we ask: how extreme was the 21st century drought in the last 1100 years? We developed a 1100 year long tree-ring reconstruction of warm-season drought, derived from live and dead Siberian pine (Pinus sibirica) trees growing on a Holocene lava flow in north central Mongolia. Trees growing on the lava today are stunted and widely spaced, occurring on microsites with little to no soil development. These trees are water-stressed and their radial growth is correlated with both soil water availability (scPDSI) and grassland productivity (Normalized Difference Vegetation Index (NDVI)). Our reconstruction, calibrated and validated on instrumental June-August scPDSI (1959-2009) account for >57% of the variability in the regional scPDSI when >70% of the annual rainfall occurs. Our tree-ring data combined with meteorological data suggests that the early 21st century drought was the hottest and one of the most severe droughts in the last 1100 years. These results are consistent with model projections of warming in Inner Asia where rising temperatures will contribute to increased water stress, independent of changes in rainfall. Future warming may overwhelm increases in precipitation leading to similar high temperature droughts, with potentially severe environmental and social consequences for modern Mongolia. Long records of past climate variability can help us understand the relative importance of climate versus land management in catalyzing social change and help prepare societies for the full range of future climatic extremes.