Seminar by Gerald H. Haug from Max Planck Institute for Chemistry, Mainz
02 October 2019
10:00 - 11:00
The Seminar is being held in Room 1010 (Jasmin) - Intergrated mechanical engineering building. Click here for the campus map.
High-resolution paloeclimate reconstructions show a strong relationship between climatically induced changes in environmental conditions and social, political, and economic responses in several parts of the world during the past millennia. One climate archive with an appropriate memory is the anoxic Cariaco Basin off northern Venezuela. Millimeter to micrometer-scale geochemical data in the annually laminated sediments of the Cariaco have been interpreted to reflect variations in the mean annual position of the Intertropical Convergence Zone (ITCZ) over tropical South America during the past millennia. These data show that the Terminal Collapse of the Classic Maya civilization occurred during an extended dry period with three separate multi-year droughts during the AD 800s. The sediments of lake Huguang Maar in coastal southeast China provide a data set of comparable quality and resolution. They record the strength of winter monsoon winds at subdecadal resolution since the last ice age. The record indicates a stronger winter monsoon when cave stalagmite oxygen isotope data indicate a weaker summer monsoon, which is best explained by migrations in the ITCZ. These droughts associated with southward ITCZ migration may have played a role in the termination of several Chinese dynasties. A remarkable similarity of ITCZ migration in east Asia and the Americas from 700 to 900 AD raises the possibility that the coincident declines of the important Tang Dynasty in China and the Classic Maya in Central America were catalyzed by the same ITCZ migrations. Also the very recent past shows the importance of the rate of climate changefor socio-political impacts, as rapid changes still lead to disconnects between social policies and environmental realities.