DGESL : About : Jessica Conroy

The scientific consensus is that humans are rapidly transforming the Earth’s climate due to emissions of greenhouse gases. How can we expect the Earth’s climate to change in the future? With reliable predictions of future climate change, perhaps we can alleviate the suffering that droughts, floods, heat waves, and hurricanes can cause to society. We rely on computer models to tell us how future climate might change, but these models must be tested. One way to test the models and validate their predictions is by comparing the model reconstructions of past climate changes with observational records of temperature, precipitation, and other atmospheric variables. However, these records only extend back to the mid 1800s. If we want to understand and simulate the full range of climate variability, we must also compare the models against proxy records of climate derived from tree-rings, corals, lake and ocean sediments, and ice cores.

My job is to reconstruct past climate variability of the Asian Monsoon using lake sediments from western Tibet. There have been many records of monsoon variability over the Holocene, which show that the monsoon weakened in response to a gradual decrease in seasonal solar insolation over thousands of years. However, I am more concerned with monsoon variability on shorter timescales. How can the monsoon change in one generation? In a century? What drives this type of monsoon variability? Do similar changes occur across the entire monsoon region, or are they heterogeneous? By answering questions like these, we will better understand future monsoon variability in a warmer world, and in turn how living conditions will change for the two-thirds of the world’s population that reside in the monsoon region.

My study region is also an area where past monsoon variability may have played a role in the collapse of an ancient civilization. The Purang polity, the only major civilization in western Tibet, collapsed some time between 1000 and 1400 AD, about the same time that some proxy climate records hint at an a sudden monsoon weakening. The new, high resolution climate records from western Tibet that will result from my dissertation will help us to constrain the nature and timing of monsoon variability around 1000-1400 AD and will aid archaeologists in identifying the linkages between climate and past society.

	Jessica Conroy Ph.D. Student M.S. The University of Arizona 2006 B.A. The College of Wooster 2003 summa cum laude Office: Gould-Simpson Room 350 Telephone Number: 1.520.621.8025 Office: Gould-Simpson Room 346 Telephone Number: 1.520.621.2219 E-mail Address: jconroy@email.arizona.edu	Mailing Address 1040 E. Fourth St. Department of Geosciences University of Arizona Gould-Simpson Room 208 Tucson, AZ 85721-0077 Telephone Number 1.520.621.8025 Facsimile Number 1.520.621.2672


The scientific consensus is that humans are rapidly transforming the Earth’s climate due to emissions of greenhouse gases. How can we expect the Earth’s climate to change in the future? With reliable predictions of future climate change, perhaps we can alleviate the suffering that droughts, floods, heat waves, and hurricanes can cause to society. We rely on computer models to tell us how future climate might change, but these models must be tested. One way to test the models and validate their predictions is by comparing the model reconstructions of past climate changes with observational records of temperature, precipitation, and other atmospheric variables. However, these records only extend back to the mid 1800s. If we want to understand and simulate the full range of climate variability, we must also compare the models against proxy records of climate derived from tree-rings, corals, lake and ocean sediments, and ice cores. My job is to reconstruct past climate variability of the Asian Monsoon using lake sediments from western Tibet. There have been many records of monsoon variability over the Holocene, which show that the monsoon weakened in response to a gradual decrease in seasonal solar insolation over thousands of years. However, I am more concerned with monsoon variability on shorter timescales. How can the monsoon change in one generation? In a century? What drives this type of monsoon variability? Do similar changes occur across the entire monsoon region, or are they heterogeneous? By answering questions like these, we will better understand future monsoon variability in a warmer world, and in turn how living conditions will change for the two-thirds of the world’s population that reside in the monsoon region. My study region is also an area where past monsoon variability may have played a role in the collapse of an ancient civilization. The Purang polity, the only major civilization in western Tibet, collapsed some time between 1000 and 1400 AD, about the same time that some proxy climate records hint at an a sudden monsoon weakening. The new, high resolution climate records from western Tibet that will result from my dissertation will help us to constrain the nature and timing of monsoon variability around 1000-1400 AD and will aid archaeologists in identifying the linkages between climate and past society.