A 4,000 Year Stalagmite Record of Extreme Rainfall Events in Tropical Western Australia

April 27th, 2013

Global environmental change poses several risks, including the possibility of increased frequency and strength of severe weather events. Though extreme weather events are difficult to define precisely, they include, but are not restricted to, tropical cyclones (a.k.a. hurricanes and typhoons) and particularly intense rainfall episodes within summer monsoons.

However, the main problem associated with present studies of tropical cyclone and monsoon activity is that they are based on limited data sets. In order to better understand the effects global climate change may have on extreme rainfall events, data spanning longer stretches of time, particularly time periods associated with sea surface temperature (SST) and/or atmospheric temperatures different from the present, need to be evaluated.

In the Kimberley Region of Western Australia, mud layers in aragonite stalagmites were deposited during flooding events of cave KNI-51. Dates of one such stalagmite, KNI-51-11, are characterized by errors of +/- 1 year over the past 100 years allowing for comparison to historical records. To calibrate the modern record, a model was created by analyzing daily rainfall data from 1969-2009.

From this model, which was based on the two day total of the average of the three nearby rain stations, mud layers were found to correlate approximatelythree quarters of the time to rainfall peaks (>100mm). This model is used to examine past mud layer occurrences in a collection of stalagmites spanning the late Holocene from the same cave and were compared to regional reconstructions of SST and global temperature to assess what links, if any, may connect them.

Angelique Gonzales, ’14
Julesburg, CO
Majors: Environmental Studies, Geology

Sponsor: Rhawn Denniston

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