Australia’s killer bushfires have their origins in Indian Ocean

Sydney, March 25 (ANI): Climate experts have uncovered a link between the Indian Ocean Dipole (IOD) and the killer bushfires in Australia.

Found by Dr Wenju Cai and Tim Cowan, of CSIRO’s Marine and Atmospheric Research, the link indicates that a weather pattern centred on the Indian Ocean may provide an early warning system for major bushfires in southern Australia.

According to a report by ABC News, 11 of 16 major bushfires in Victoria since 1950 have been preceded by what is known as a positive IOD event.

Cai said that an unprecedented three consecutive positive IOD events preceded February’s devastating Black Saturday bushfires.

The IOD refers to temperature fluctuations in the east and western Indian Ocean.

In its negative phase, the IOD brings cool water to the ocean west of Australia and warm water to the north, leading to winds that bring rain-bearing air over the continent.

In the positive phase, water temperatures are reversed and less rainfall travels to Australia, particularly to Victoria where the negative IOD provides winter and spring rains.

As part of their research, Cai and Cowan recorded changes in the IOD using Argo floats, robotic devices that measure the subsurface ocean temperature.

They found the IOD was in an “unprecedented” positive state for three consecutive years leading up to 2009.

They said that this preconditioned the environment to the extent that it was almost inevitable the bushfires, which claimed more than 200 lives, would occur.

“If you look at the accumulative soil moisture in Victoria, it’s unprecedented, it’s never been so dry,” said Cai.

The researchers also found an IOD link to the Ash Wednesday bushfires of February 1983, with a positive event reducing rainfall during the winter of 1982.

According to Cai and Cowan, climate change projections show the frequency of positive IOD events will increase in the future.

“Almost all climate models say under climate change we are going to have an Indian Ocean warming pattern,” said Cai.

“That means it has to be manifested in either more frequent positive IOD events or higher intensity positive IODs,” he added. (ANI)

Indian Ocean plays profound role in driving southern Australian drought

Canberra, Feb 5 (ANI): In a new research, scientists have found that the Indian Ocean plays a profound role in driving the southern Australian drought.

According to a report in ABC News, the researchers, from the Climate Change Research Centre at the University of New South Wales, discovered that Australia’s severe drought is being driven by temperature fluctuations in the Indian Ocean.

“We have found the Indian Ocean plays a profound role in driving the southern Australian drought,” said Dr Caroline Ummenhofer of the Climate Change Research Centre at the University of New South Wales.

“We really hope this will improve forecasting of rainfall in that area,” she added.

Traditionally, scientists have linked drought in Australia with El Nino – a climate pattern resulting from temperature fluctuations in the Pacific Ocean.

The reverse of El Nino – or La Nina is thought to be responsible for bringing drought-breaking rains to Australia.

But, despite numerous La Nina events, over the past 15 years, southern Australia has been virtually starved of rainfall, raising questions over the role of the Pacific Ocean climate pattern.

“El Nino and La Nina cycles cannot explain the cause,” said Ummenhofer.

For their research, Ummenofer and colleagues investigated the role of a climate pattern called the Indian Ocean Dipole (IOD).

In its negative phase, the IOD is characterised by cool water to the west of Australia and warm water to the north, leading to winds that bring warm moist, rain-bearing air to the continent.

In the positive phase, water temperatures are reversed and less moisture travels to Australia.

Looking back over the last 100 years of data, Ummenhofer and colleagues found that all of Australia’s long-lasting droughts, including the Federation drought (1885-1902) and the World War II drought (1937-1945), were linked to a low number of negative IOD phases.

According to the researchers, the most recent big dry has seen no negative phases at all.

Ummenhofer said that for the past 15 years, the IOD has been either neutral or positive and in the last few years there were three consecutive positive phases.

“This is something new that in the historical record has never happened before,” said Ummenhofer. (ANI)