Rainfall, Ecosystems, and Fire in Warm Late Neogene Climates of the Lake Baikal Region

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

Climate change makes acute droughts and prolonged heat waves that stimulate wildfires more common. These fires have devasted local communities in Siberia and Canada while blanketing large municipalities in Siberia, Canada, Western Europe, and the United States with smoke. Furthermore, boreal regions store huge amounts of carbon in soils that, if released to the atmosphere, would accelerate global warming. Frequent wildfires in boreal forests lead to carbon release by shifting forest to grasslands and by accelerating permafrost melt. Climate models predict dramatic ecosystem changes, with boreal forests replaced by extensive grasslands and a new temperate deciduous forest ecosystem occupying much of Siberia by the end of the 21st century. However, regional differences in wildfires and the short time span of satellite observations make it difficult to verify these model predictions. This project uses warm periods in Earth’s past to test climate model predictions of hydroclimate, fire and, vegetation cover in Siberia in warm climates, such as expected by the end of the 21st century. Models will be tested by comparison to a record of past climate, vegetation, and wildfire over the past 8.4 million years that is preserved in organic and mineral fossils in a drillcore from Lake Baikal, Russia. The primary purpose of this project is the generation of this new paleoclimate record. The broader impacts of this study are that validation of models will make possible more accurate forecasts of future carbon emission as well as the human habitability and economic potential of Siberia in coming decades, with potential ramifications for regional security. The project will also support undergraduate research experiences at a federally designated Hispanic-serving institution. This project will test two hypotheses, based upon climate model predictions and studies of recent climate and wildfire trends. The first, that growing season lengthens and precipitation is more equable in Siberia under warm climate conditions, will be tested by paired analyses of plant-wax hydrogen isotopes (precipitation isotope proxy) and branched glycerol dialkyl glycerol tetraethers (temperature proxy). The second, that fire regime in the Lake Baikal region is a function of temperature, hydroclimate, and biome, will be tested by paired analyses of polycyclic aromatic hydrocarbons and charcoal (fire proxies) in the same samples as the plant-wax hydrogen isotope and branched glycerol dialkyl glycerol tetraether measurements. Timeseries of these data will reveal the regional response of climate, vegetation, and wildfires in Siberia to global climate trends over the past 8.4 million years. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.