Extension of summer (June–August) temperature records for northern Inner Mongolia (1715–2008), China using tree rings

This paper presents a spatially and temporally improved reconstruction of mean summer (June–August) temperature derived from tree-ring width data of Dahurian larch (Larix gmelinii Rupr.) from the northern Great Xing'an Mountains, Northeast China. Three new chronologies were added to the original 2011 reconstruction, and the reconstruction extended back to AD 1715. The reconstruction was generated using a simple linear regression method, verified by independent meteorological data, and accounts for 47.0% of the actual temperature variance during the common period (1957–2008). The reconstruction captures decadal and century-scale regional temperature variability, such as cold decades (1940s, 1930s, 1790s, 1950s and 1850s), warm decades (2000s, 1870s, 1750s, 1980s and 1840s), a cold half-century (ca. 1750–1799), and a warm half-century (ca. 1900–1949). It also reveals slightly higher frequency of cold years (20.4%) than warm years (18.0%), and a recent warming trend. Compared to the original 2011 reconstruction, this reconstruction has lower inter-annual temperature variability, high explained variance and high representativeness of regional climate. The reconstruction also correlates with the East Asian Monsoon and the Pacific Ocean signals, and indicates the feasibility of using tree rings from high latitude Northeast China to reconstruct summer temperature in permafrost forest environments

Response of radial growth to warming and CO2 enrichment in southern Northeast China: a case of Pinus tabulaeformis

The southern part of northeast China has experienced a marked warming and drying climate. We provide dendrochronological evidence for atmospheric CO2 fertilization and the impacts of warming on Chinese pine (Pinus tabulaeformis) growth. The results of this study show that increased temperature has a negative effect on pine growth during a major part of the growing season and a weakly positive effects on growth during the remaining portion of the year. The monthly temperatures explain ca. 20 % of the total variance in the annual radial growth of Chinese pine from 1901 to 2009. An increase of approximately 3–5 °C is the maximum that Chinese pine can tolerate in this region with an annual rainfall of 500–700 mm. Our results suggest a that there is a proportional response to warming only up to a maximum of 1 °C warming, and indicate the complexities of succession in forest ecosystems in terms of adaptation and evolution in local pine populations under a rapid warming condition. In addition, increasing atmospheric CO2 concentrations have a positive effect on tree growth. This effect can be detected with conventional dendrochronological methods

Tree-ring based precipitation variability since AD 1828 in northwestern Liaoning, China

A 183-year record of total precipitation from September to current July was reconstructed using tree rings from Chinese pine (Pinus tabulaeformis) to explore regional moisture variations in northwestern Liaoning province. The reconstruction accounts for 35.4% of the total variance of the instrumental precipitation from 1957 to 2010. The reconstruction shows eleven persistent dry periods (e.g. 1856–1866, 1886–1891, 1898–1905), and eleven persistent wet periods (e.g. 1835–1855, 1867–1878, 1892–1897). Spectral analysis of the reconstruction shows several significant spectral peaks in the ca. 2–4-year periodicity band, suggesting inter-annual variability of El Niño-Southern Oscillation (ENSO). The precipitation reconstruction shows correlations related to the East Asian Monsoon and possible teleconnection of regional moisture variations to Pacific Ocean signals, such as El Niño and La Niña

A long-term context (931–2005 C.E.) for rapid warming over Central Asia

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Quaternary Science Reviews 121 (2015): 89-97, doi:10.1016/j.quascirev.2015.05.020.Warming over Mongolia and adjacent Central Asia has been unusually rapid over the past few decades, particularly in the summer, with surface temperature anomalies higher than for much of the globe. With few temperature station records available in this remote region prior to the 1950s, paleoclimatic data must be used to understand annual-to-centennial scale climate variability, to local response to large-scale forcing mechanisms, and the significance of major features of the past millennium such as the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) both of which can vary globally. Here we use an extensive collection of living and subfossil wood samples from temperature-sensitive trees to produce a millennial-length, validated reconstruction of summer temperatures for Mongolia and Central Asia from 931 to 2005 CE. This tree-ring reconstruction shows general agreement with the MCA (warming) and LIA (cooling) trends, a significant volcanic signature, and warming in the 20th and 21st Century. Recent warming (2000-2005) exceeds that from any other time and is concurrent with, and likely exacerbated, the impact of extreme drought (1999-2002) that resulted in massive livestock loss across Mongolia.This research was supported by the National Science Foundation under grants AGS-PRF #1137729, ATM0117442, and AGS0402474

A long-term context (931–2005 C.E.) for rapid warming over Central Asia

Warming over Mongolia and Central Asia has been unusually rapid over the past few decades, particularly in the summer, with surface temperature anomalies higher than for much of the globe. With few temperature station records available in this remote region prior to the 1950s, paleoclimatic data must be used to understand annual-to-centennial scale climate variability, local response to large-scale forcing mechanisms, and the significance of major features of the past millennium such as the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) both of which can vary globally. Here we use an extensive collection of living and subfossil wood samples from temperature-sensitive trees to produce a millennial-length, validated reconstruction of summer temperatures for Mongolia and Central Asia from 931 to 2005 CE. This tree-ring reconstruction shows general agreement with the MCA (warming) and LIA (cooling) trends, a significant volcanic signature, and warming in the 20th and 21st Century. Recent warming (2000–2005) exceeds that from any other time and is concurrent with, and likely exacerbated, the impact of extreme drought (1999–2002) that resulted in massive livestock loss across Mongolia

Is eastern Mongolia drying? A long-term perspective of a multidecadal trend

Temperatures in semiarid Mongolia have rapidly risen over the past few decades, and increases in drought, urban development, mining, and agriculture have intensified demands on limited water resources. Understanding long-term streamflow variation is critical for Mongolia, particularly if alterations in streamflow are being considered and because of the potential negative impacts of drought on the animal agriculture sector. Here, we present a temporally and spatially improved streamflow reconstruction for the Kherlen River. We have added 11 new records in comparison with two in the original 2001 reconstruction. This new reconstruction extends from 1630 to 2007 and places the most recent droughts in a multicentennial perspective. We find that variations in streamflow have been much greater in the past than in the original study. There was higher variability in the mid to late 1700s, ranging from severe and extended drought conditions from 1723 to 1739 and again in 1768–1778 to two decadal length episodes of very wet conditions in the mid 1700s and late 1700s. Reduced amplitude is seen in the mid-1800s, and several pluvial events are reconstructed for the 1900s. Although recent droughts are severe and disturbing economic and ecological systems in Mongolia and it appears that eastern Mongolia is drying, the drying trend since the late 1900s might in fact be accentuated by a change from a particularly wet era in Mongolia. The recent drought might be a return to more characteristic hydroclimatic conditions of the past four centuries in Mongolia

Dzuds, droughts, and livestock mortality in Mongolia

Recent incidences of mass livestock mortality, known as dzud, have called into question the sustainability of pastoral nomadic herding, the cornerstone of Mongolian culture. A total of 20 million head of livestock perished in the mortality events of 2000–2002, and 2009–2010. To mitigate the effects of such events on the lives of herders, international agencies such as the World Bank are taking increasing interest in developing tailored market-based solutions like index-insurance. Their ultimate success depends on understanding the historical context and underlying causes of mortality. In this paper we examine mortality in 21 Mongolian aimags (provinces) between 1955 and 2013 in order to explain its density independent cause(s) related to climate variability. We show that livestock mortality is most strongly linked to winter (November–February) temperatures, with incidences of mass mortality being most likely to occur because of an anomalously cold winter. Additionally, we find prior summer (July–September) drought and precipitation deficit to be important triggers for mortality that intensifies the effect of upcoming winter temperatures on livestock. Our density independent mortality model based on winter temperature, summer drought, summer precipitation, and summer potential evaporanspiration explains 48.4% of the total variability in the mortality dataset. The Mongolian index based livestock insurance program uses a threshold of 6% mortality to trigger payouts. We find that on average for Mongolia, the probability of exceedance of 6% mortality in any given year is 26% over the 59 year period between 1955 and 2013

Hydroclimate Variations in Central and Monsoonal Asia over the Past 700 Years

Peer reviewe

Estimating return intervals for extreme climate conditions related to winter disasters and livestock mortality in Mongolia

Mass livestock mortality events during severe winters, a phenomenon that Mongolians call dzud, cause the country significant socioeconomic problems. Dzud is an example of a compound event, meaning that multiple climatic and social drivers contribute to the risk of occurrence. Existing studies argue that the frequency and intensity of dzud events are rising due to the combined effects of climate change and variability, most notably summer drought and severe winter conditions, on top of socioeconomic dynamics such as overgrazing. Summer droughts are a precondition for dzud because scarce grasses cause malnutrition, making livestock more vulnerable to harsh winter conditions. However, studies investigating the association between climate and dzud typically look at a short time frame (i.e., after 1940), and few have investigated the risk or the recurrence of dzud over a century-scale climate record. This study aims to fill the gaps in technical knowledge about the recurrence probability of dzud by estimating the return periods of relevant climatic variables: summer drought conditions and winter minimum temperature. We divide the country into three regions (northwest, southwest, and east Mongolia) based on the mortality index at the soum (county) level. For droughts, our study uses as a proxy the tree-ring-reconstructed Palmer drought severity index (PDSI) for three regions between 1700–2013. For winter severity, our study uses observational data of winter minimum temperature after 1901 while inferring winter minimum temperature in Mongolia from instrumental data in Siberia that extend to the early 19th century. Using a generalized extreme value distribution with time-varying parameters, we find that the return periods of drought conditions vary over time, with variability increasing for all the regions. Winter temperature severity, however, does not change with time. The median temperature of the 100-year return period for winter minimum temperature in Mongolia over the past 300 years is estimated as −26.08 ∘C for the southwest, −27.99 ∘C for the northwest, and −25.31 ∘C for the east. The co-occurrence of summer drought and winter severity increases in all the regions in the early 21st century. The analysis suggests that a continued trend in summer drought would lead to increased vulnerability and malnutrition. Prospects for climate index insurance for livestock are also discussed

Three centuries of shifting hydroclimatic regimes across the Mongolian Breadbasket

In its continuing move toward resource independence, Mongolia has recently entered a new agricultural era. Large crop fields and center-pivot irrigation have been established in the last 10 years across Mongolia's "Breadbasket": the Bulgan, Selenge and Tov aimags of northcentral Mongolia. Since meteorological records are typically short and spatially diffuse, little is known about the frequency and scale of past droughts in this region. We use six chronologies from the eastern portion of the breadbasket region to reconstruct streamflow of the Yeruu River. These chronologies accounted for 60.8% of May–September streamflow from 1959 to 1987 and 74.1% from 1988 to 2001. All split, calibration-verification statistics were positive, indicating significant model reconstruction. Reconstructed Yeruu River streamflow indicates the 20th century to be wetter than the two prior centuries. When comparing the new reconstruction to an earlier reconstruction of Selenge River streamflow, representing the western portion of the breadbasket region, both records document more pluvial events of greater intensity during 20th century versus prior centuries and indicate that the recent decade of drought that lead to greater aridity across the landscape is not unusual in the context of the last 300 years. Most interestingly, variability analyses indicate that the larger river basin in the western breadbasket (the Selenge basin) experiences greater swings in hydroclimate at multi-decadal to centennial time scales while the smaller basin in the eastern portion of the breadbasket (the Yeruu basin) is more stable. From this comparison, there would be less risk in agricultural productivity in the eastern breadbasket region, although the western breadbasket region can potentially be enormously productive for decades at a time before becoming quite dry for an equally long period of time. These results indicate that farmers and water managers need to prepare for both pluvial conditions like those in the late-1700s, and drier conditions like those during the early and mid-1800s. Recent studies have indicated that cultures with plentiful resources are more vulnerable when these resources become diminished. Thus, the instrumental records of the 20th century should not be used as a model of moisture availability. Most importantly, the geographic mismatch between precipitation, infrastructure, and water demand could turn out to be particularly acute for countries like Mongolia, especially as these patterns can switch in space through time