Antarctic ice cores reveal Australian drought risk worse than thought

The ice core records show that eastern Australia has a greater than thought risk of a dry spell.

The research, led by Dr. Anthony Kiem from the University of Newcastle, has significant implications for water security and management across Australia and internationally.

The team compared 150 years of observations of the Interdecadal Pacific Oscillation (IPO) climate variability index, which controls decadal drought and flood risk across eastern Australia, with a reconstruction of the index based on 2,000 years of climate records.

Until now, the IPO was assumed to alternate every 30 years between positive and negative phases.

The IPO phases change the risk of fire, flood and dry weather.

The IPO negative or wet periods are shorter and less frequent than the positive or dry phases according to new ice core research.

The wet phases lasted on average seven years and occurred 10% of the time, while the dry phases lasted on average 61 years.

Dr. Kiem said, "This could be catastrophic for almost all of Australia, which rely on the negative phases to replenish river basins and restore soil hydration after periods of dry weather."

The long wet phase that occurred between 1947 and 1976 is believed to be the reason for the divergence between the ice core reconstruction of the IPO and instrumental observations. Much of eastern Australia's water infrastructure was built or planned during this wet period.

Dr. Kiem said that what happened in the mid 20th century skews our expectations of what is normal for rain and flooding.

This has serious implications for the assessment of flood risk, which should be re-calculated to account for positive, dry IPO phases being the norm, and much more likely than suggested by the last 150 years of observations.

The research was published in the journal Communications Earth and Environment.

More information: Tessa R. Vance et al, Pacific decadal variability over the last 2000 years and implications for climatic risk, Communications Earth & Environment (2022). DOI: 10.1038/s43247-022-00359-z Journal information: Communications Earth & Environment Citation: Antarctic ice cores reveal Australian drought risk worse than thought (2022, February 18) retrieved 18 February 2022 from https://phys.org/news/2022-02-antarctic-ice-cores-reveal-australian.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.