Volcanic ash in the Antarctic Ice Sheet and its possible climatic implications

Approximately 2000 individual ash falls are preserved in deep cores from Antarctica. The bulk of the debris is composed of dust-sized particles of glass that can probably be attributed to volcanic sources in Antarctica, though sources outside Antarctica cannot be entirely discounted. A period of sustained infall of ash occurred during the interval 30 000 to 16 000 years ago, and isotopic (paleotemperature) data from the same cores indicate that a significant cooling of the atmosphere over Antarctica occurred at the same time. This cooling trend did not terminate until deposition of ash had virtually ceased, suggesting possibly a cause and effect relationship involving the solar-depleting effect of volcanic dust in the Antarctic stratosphere. It is conceivable that widespread eruption of volcanic ash in Antarctica during the latter part of the Wisconsin may also have triggered world-wide cooling during this period — effectively intensifying the existing glacial regime.