Ice core data research reverses drought risk

Climate data collected deep in the 2,000-year-old Antarctic ice has revealed the risk of drought in Australia is far worse than previously thought.

The research points to future dry spells that could be nothing short of “catastrophic” for Australia’s eastern watersheds, according to lead scientist Dr Anthony Kiem of Newcastle University.

He was part of a team of researchers that looked at 150 years of data measuring weather and ocean change in the Pacific, known as the Pacific Interdecadal Oscillation (IPO) Climate Variability Index.

The IPO controls the risk of drought and flooding in eastern Australia over periods of about a decade, by switching between negative values ​​which cause a wetter climate and positive values ​​which cause a wetter climate. dry.

Scientists then looked at 2,000 years of climate records taken from Antarctic ice cores and used them to reconstruct changes in the IPO over time.

Data from the old ice samples led to a very different set of numbers – and some worrying conclusions.

He showed that wet periods were much shorter and less frequent than previously thought.

It had been assumed that the IPO goes from wet to dry and back again approximately every 15 to 30 years, but the new data shows that the wet phases only last about seven years on average and only occur about 10% of the time.

Dry periods, on the other hand, last on average more than 60 years.

“It could be catastrophic for almost all the watersheds in eastern Australia, which depend [on wet periods] to recharge watersheds and river reservoirs and restore soil moisture after periods prone to drought,” said Dr Kiem.

The difference was probably due to an unusually long wet period between 1947 and 1976 – when most water infrastructure on the east coast was planned or built.

This likely skewed scientists’ expectations of how much rainfall and runoff to expect, according to Dr Kiem.

“This has serious implications for drought and flood risk assessments, which should be recalculated to take into account that positive, dry IPO phases are the norm, and much more likely than the last 150 years suggest. observations,” he said.

Scientists from the Australian Antarctic Program Partnership and the University of Newcastle conducted the research, which is published in the journal Communications Earth and Environment.

Sean N. Ayres