Effects of Volcanic Eruptions on Climate in Inner Asia from 600 BCE to 2015 CE

Volcanic eruptions have strongly influenced regional and global climate on many time scales. However, past studies have focused solely on the temperature variability of climate due to eruptions, using modern eruptions with the aid of satellite records. By using tree-ring data from a variety of sites that are temperature or moisture limited, it may be possible to attain a more complete understanding of the climatic effects of large eruptions from the past 2600 years. We used existing tree-ring data from Mongolia to understand how volcanic eruptions influence different climatic variables (temperature, moisture, and solar irradiance) in Inner Asia. This study, part of a larger research project on human ecology of Inner Asia, focuses on past volcanic eruptions ( 600 BCE to 2015 CE) at three sites in north central Mongolia: Solongotyn Davaa (48.3°N, 98.93°E), a temperature limited site, Khorgo Lava (48.17°N, 99.87°E), and Urgaat Lava (46.40°N, 101.46°E), both moisture limited sites. We collected more than 200 tree-ring samples of Siberian pine (Pinus sibirica) from the three sites. We used the Grid Analysis and Display System to run composite analyses using Climatic Research Unit temperature and precipitation data to test how modern eruptions between 1961 and 1999 influenced temperature and precipitation regimes in Mongolia. Four eruptions were analyzed and both composite analyses suggest that each variable is altered by volcanic eruptions during the 1 to 2 years following an eruption. We then used superposed epoch analysis to evaluate how past eruptions affect regional climate in Mongolia by separating temperature and precipitation variables. Our results indicate that most of Mongolia experienced 0.5°C cooler and dryer conditions following major eruptions. This research shows that tree-ring data is invaluable to studying volcanic eruptions by extending the time range of eruptions available to study and providing a more complete understanding of how they affect climate.