Twenty Australians have lost their lives in floods this year, as authorities continue their search and rescue efforts

For the third time this year, floods have battered Australia’s largest city.

Some areas have received eight months of rain in just four days.

The Bureau of Meteorology (BOM) says some parts of New South Wales have seen 800mm alone. For perspective, Greater London receives this type of rainfall over the course of a year.

There are more than 100 evacuation orders across Greater Sydney for the current emergency.

It’s the typical narrative for disasters like these, where a cesspit of data floods headlines.

It comes as the BOM confirms this season’s La Niña has ended, so what is causing these floods?

Divulging the data

The Indian Ocean Dipole is a technical term for the differences in sea surface temperatures between the eastern and western parts of the Indian Ocean.

This phenomenon is likely to shift ‘negative’ over the coming months.

This means “warmer waters concentrate near Australia, leading to above average winter–spring rainfall as more moisture is available to weather systems crossing the continent,” according to the BOM.

Meanwhile, the SAM refers to the Southern Annular Mode. This is a term used for the non-seasonal, north-south movement of the strong westerly winds.

When the SAM is in the ‘positive’ phase, it directs more moisture-filled air into eastern Australia.

The BOM says this is “driving above average rainfall and more east coast lows”.

This has forced a cargo ship to remain at anchor by the ferocious conditions off the coast of Sydney.

In fact, this happened 15 years ago when storms grounded the Pasha Bulker—a 40,000 tonne bulk carrier ship.

Is this climate change in action?

It is difficult to link any single flood to climate change. But many climate models suggest Australia will repeatedly fall victim to climate change.

Critically, these areas have been battered by heavy rains in recent months. The La Niña has also saturated the ground and filled dams. These are some of the crucial factors that lead to flash flooding.

“Similarly, we’re now working hard together to make sure that impacted communities get the financial and other assistance they need as soon as possible,” Senator Murray Watt says.

Sydney’s bustling population has pushed development into low-lying areas, which also places residents at an increased risk.

Greg Mullins is the leader of the Emergency Leaders for Climate Action group, who recently met with Australia’s new government.

“There is absolutely no doubt extreme weather events are being intensified because of climate change.”

“The science is very clear that we’re seeing wild fluctuations between periods of flood and fire, because of warming. On the East Coast of Australia in the last 18 months we’ve now had four major floods,” he says.

Senator Watt says he is committed to learning from past natural hazards, which turn into disasters when they intersect with vulnerable communities, devastate infrastructure, and lead to economic consequences.

This occurred when over 400 people were killed when deluge swept through South Africa in April.

“It’s time for the world to wake up and take real action on climate change. Communities having to deal with flood event after flood event is absolutely affecting our response and recovery,” Mullins says.