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A powerful weather system off the east coast of Australia has unloaded heavy rain for days in the state of New South Wales, leaving Sydney on track for the wettest year in history.
The torrents have caused widespread flooding in eastern New South Wales, for the fourth time in less than 18 months. The flooding has caused more than 100 evacuation orders.
Hundreds rescued when Sydney suffers its fourth flood in less than 18 months
Since Friday, Sydney has observed 8.6 inches (220 mm) of rain, while surrounding areas have seen much more, some approaching 28 inches (700 mm), which is around the amount London sees. in a whole year.
Sydney accumulated the same amount of rain for four days that is typically seen in a month and a half, according to WeatherZone, an Australian weather information company.
The city has recorded about 70 inches (1,769 mm) of rain this year, with a jump of 7.5 inches beyond 1890, its next wettest year through July 4th. And, with almost five months left in the year, it has already reached at least its 11th wettest year in history.
Many areas of Sydney recorded about 8 inches (200 mm) of rain over the past week.
73 mm more during the last 24 hours make the total annual operation of #Sydney is 1,769 mm. Not only is it the wettest year on record in Sydney to date with 191 mm (above 1578.3 mm since 1890), it is also NOW the 11th wettest year in the city in records dating back to 1859 .pic.twitter.com/JvZjIgTrew.
– Ben Domensino (@Ben_Domensino) July 5, 2022
The scientists attributed the excess rain to a combination of factors:
- The presence of several natural climatic factors: Conditions in La Niña, a periodic cooling of the tropical Pacific Ocean, are related to increased rainfall in eastern Australia. A periodic cooling of the western Indian Ocean, connected to La Niña, is associated with increased rainfall in southern Australia. A positive southern annular mode causes easterly winds to carry moist air from the Tasman Sea to eastern Australia, which falls as rain.
- Man-made climate change, which is warming the atmosphere and oceans and intensifying precipitation events globally.
The Australian Bureau of Meteorology also noted that warm ocean waters helped intensify the rains.
“During this recent rain event, the very warm waters of the Australian coast (21-23 ° C) provided additional energy and moisture that contributed to the deep descent and east coast, leading to the relative concentration of strong rains in a 24 hour. period, “he wrote.
The heaviest rainfall in New South Wales until Tuesday morning had fallen at Brogers Creek, about 65 miles south of Sydney, which was 36.7 inches (933 mm). WeatherZone wrote that these rains only have a probability of occurrence of 1 to 2 percent in a given year. Brogers Creek experienced more than Melbourne, Canberra, Hobart, Adelaide or Perth in one month.
The 933 mm of rain that fell in Brogers Creek, NSW over the past four days, has an annual excess probability (AEP) of 1 to 2%. This is statistically a rainfall rate of 1 in 50 to 100 years for this location.
More details> pic.twitter.com/2j5Yo2owDU
– Ben Domensino (@Ben_Domensino) July 5, 2022
Darkes Forest, about 40 miles south of Sydney, recorded 27.4 inches (697 mm) of rain.
Researchers say climate change is making the situation worse. Australia has warmed by about 2.6 degrees (1.5 centimeters) since 1910. A heated atmosphere retains more moisture and can increase the intensity of extreme rain events.
“Australia has long been a continent of droughts and flood rains; That said, projections indicate that climate change will increase this variability, “said in an email Chiara Holgate, a researcher at the National University of Australia and the ARC Center of Excellence for climate extremes.” Observations show that there has been an increase in the intensity of heavy rainfall events in Australia, including short-term events, which may be associated with sudden flooding. “
Holgate said Australia needs to prepare for more intense flood events, as flooding is one of the most costly disasters the country faces. The floods in southeast Queensland and New South Wales in February and March cost about $ 3.35 billion in insured losses, according to the Australian Insurance Council, making it the most expensive flood. of the history of the country.
“Large floods are a threat to the supply of water and safe drinking water, taking the operation of the water treatment plant by increasing the sediment load and potential pollutants,” the scientist said. environmentalist Klaus Joehnk in a press release.
Researchers have found that climate change has exacerbated several recent flood events around the world. The World Weather Attribution group found that Brazil’s record flood in May, which displaced at least 25,000 people and killed more than 130, was exacerbated by climate change. The group also found that global warming caused torrential rains in South Africa in April, killing more than 400 people, twice as likely to occur and between 4 and 8 percent more intense. .
On Tuesday, the Australian Bureau of Meteorology tweeted that heavy flooding continued in parts of New South Wales, although it was reduced to Sydney. More than 20 alerts were active.
Until Wednesday, the most intense additional rain is projected mainly in northern Sydney, where the European forecast model simulates up to 1 to 3 inches (30 to 80 mm) of additional rain.