Earth’s climate can exist in many stable states that are vastly different from the modern climate state. Understanding modern and future climate requires a thorough understanding of the full range of possible climate states and the processes that trigger transitions between states. Quantitative reconstructions of past climate variables provide constrains on the magnitude, mechanisms and feedbacks involved in producing stable climate states. As such, they provide insights into past climate states unobservable today.
This thesis focuses on quantifying three metrics of past climate systems: (a) quantitative rainfall amount, which provides means for assessing how the spatial distribution of rainfall changed in the past, (b) the isotopic composition of past rainwater (δP ), which provides means for understand- ing how atmospheric circulation changed in the past, and (c) relative humidity, which provides estimates of evaporative processes and hydrospheric fluxes.
The regions studied are in the two far reaches of the Asian continent. In eastern Asia, changes in rainfall amount and δP over the past 125 ka were studied using geomorphological evidence from a closed basin lake in Inner Mongolia, China and compound-specific δDwax and δ13Cwax from organic molecules in lake sediments. In western Asia, the research focused on processes that govern modern δP and modern δDwax and δ13Cwax in soils. In addition the hydrological regime of the Eastern Mediterranean and the Levant during the Last Glacial Maximum were studied using evidence from speleothem δ18Oc and foraminifera δ18O.
These records provide empirical and quantitative information about rainfall amount, δP and relative humidity at singular locations, and as such provide the building blocks for producing coherent large-scale reconstruction of the migration of rain-belts in the past.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/D8F481HM |
| Date | January 2017 |
| Creators | Goldsmith, Yonaton A. |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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