[Aqualist] Paleoclimate seminar at ANU this Thursday at 4pm

[Claire Krause]

Hello,

I would like to draw your attention to this seminar, happening at the Research School of Earth Sciences at ANU in Canberra this Thursday. This is my PhD seminar, the final assessable task before submitting my thesis. I will be presenting my updated work on speleothem carbon and atmospheric methane that I presented at the AQUA conference earlier this year.

If you're in Canberra, please feel free to come along. This seminar is open to the public, so feel free to pass on to anyone who may be interested.

Kind regards,
Claire Krause



RSES Seminar

Jaeger Seminar Room, J1, ANU


4:00 PM, Thursday 18th September 2014


entitled:

A History of Rain, Vegetation and Methane in Sulawesi, Indonesia


by Claire Krause (RSES PhD candidate, Ocean & Climate Geoscience)

Speleothem δ13C remains an underutilized proxy because a number of factors can contribute to the δ13C signal making an unambiguous interpretation of data elusive. Known factors include climate change, karst processes, vegetation productivity and soil temperature. In this study, we combine speleothem δ13C data with model experiments to better understand the relationship between speleothem δ13C variability, tropical vegetation productivity, and glacial-interglacial changes in atmospheric methane.
Our δ13C record from southwest Sulawesi, Indonesia spans the last 40,000 y and we argue serves as a proxy for tropical vegetation and soil productivity. Changes in soil CO2 and temperature since 40 kyr BP appear to be the key driver of speleothem δ13C variability in southwest Sulawesi, supported by a strong relationship between CO2 and local temperature. Additional influences on speleothem δ13C are explored, but are not supported by other proxy records from the region or trace element analysis of the Sulawesi speleothem.
These results are compared with simulations provided by the Sheffield Dynamic Global Vegetation Model (SDGVM) forced with snapshot climate simulations covering the last 40 kyr using the HadCM3 coupled ocean-atmosphere global circulation model. Temporal changes in soil respiration rates in the model experiments are in good agreement with trends in the speleothem δ13C time series for Sulawesi, supporting our interpretation of δ13C as a proxy for vegetation productivity. The strong relationship between soil respiration and methane emissions within the SDGVM suggests that tropical vegetation plays a key role in determining the atmospheric methane budget, as is observed in the modern day. The relationship between speleothem δ13C, tropical vegetation and atmospheric methane is particularly strong during the last glacial when methane production in high-latitude boreal wetlands was suppressed.
The Sulawesi speleothem δ13C record and SDGVM model results provide new insights into the role of tropical vegetation in driving the global atmospheric methane budget over the last 40,000 y. In the tower karst terrane of southwest Sulawesi, speleothem δ13C acts as a proxy for tropical vegetation productivity, thus providing, for the first time, a direct proxy for tropical methane contributions to the last glacial atmospheric methane budget.



The talk will be followed by beers and nibbles.


PhD candidate
Research School of Earth Sciences
The Australian National University
ACT 0200
Australia

claire.krause at anu.edu.au<mailto:claire.krause at anu.edu.au>