Climate Change and Caves
Climate Change as we understand it today includes the impact human activity is having on the Earth's climate, but it also involves a natural process that has been happening for millions of years. The unique limestone caves of the Leeuwin-Naturaliste Ridge provide a privileged insight into the climate of the past.
These caves are nestled in very young limestone; just over one million years old. The natural climate change process which created these caves started with a 'glacial' period or ice age about 1.2 million years ago. Glacial periods are cold and dry because so much of the Earth's water is frozen, there is little rain and a much lower sea level. During this glacial period the sand on the sea bed was exposed to the wind and blown inland to form a series of sand dunes. As the climate became warmer and wetter, during an 'inter-glacial' period, rainfall gradually cemented these sand dunes into limestone.
The crystal formations that grow within our caves are the result of water action too; the dissolving and re-depositing of minerals over thousands of years. On a geological time scale the caves of the Leeuwin-Naturaliste Ridge are young, which means the formations within the caves will still yield their weather records. These caves are a veritable time capsule of evidence about our climate. Research currently being undertaken on samples from these cave formations will enable scientists to reconstruct rainfall records for the last one thousand years. The Augusta Margaret River Tourism Association is also funding research into the hydrology of Lake and Jewel Caves.
Using the results of these studies we will begin to understand why our caves are drying out. Has the lake disappearing from Jewel Cave and the decreasing stream levels in Lake Cave been a direct result of lower rainfall? Has land use such as farming, logging and changing fire regimes contributed to the decline?
This research may eventually help answer questions about whether this change to a drier climate is natural or human induced and enable us to better manage and preserve our unique and captivating caves.