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The Guardian
05-03-2025
- Science
- The Guardian
Is climate change supercharging Tropical Cyclone Alfred as it powers towards Australia?
Tropical Cyclone Alfred is due to hit south-east Queensland about 1am on Friday morning, bringing the risk of destructive winds, extreme flooding and storm surges to millions of people around Brisbane, the Gold Coast and northern New South Wales. After last year was recorded as the hottest on record around the world, and the hottest for Australia's oceans, what role could the climate crisis be playing in Tropical Cyclone Alfred and its impacts? Like all weather systems on the planet, tropical cyclones are forming in a world that is heating rapidly, mostly because of the burning of fossil fuels. The planet – and the world's oceans – are retaining more of the sun's energy because of the extra greenhouse gases in the atmosphere. But tropical cyclones are complex. They need ocean temperatures of at least 26.5C and the right setup of atmospheric conditions to form. In particular, they need low wind shear – that is, very little change in the wind, no matter how high they are blowing. Studies have found that global heating is expanding the tropical belt – the region where cyclones can form – and other scientists have found that on average, the point at which cyclones achieve their maximum intensity has been shifting towards the poles. Dr Savin Chand is an expert on tropical cyclones and climate change in the Australian region. 'Climate change isn't causing tropical cyclones to form because they have been forming for millennia, but the environment in which they're forming is becoming more hostile [to their formation],' the associate professor at Federation University said. 'But when they do form, we know that sea surface temperatures that are their source of energy are much warmer now than they used to be.' Chand has led research that has argued the number of tropical cyclones has fallen by 13% in the 20th century. This was in line with expectations from climate scientists that global heating could actually reduce the total number of cyclones that form – but, of those, there will be a shift to higher intensity systems. 'These sea surface temperatures and warming in the atmosphere provide fuel to the systems so, when they do form, they have more energy to feed on and this tends to make them more intense than they used to be,' said Chand. Cyclone Alfred formed in the Coral Sea towards the end of February when sea surface temperatures were almost 1C hotter than usual. The same area of low pressure and rising air known as a monsoon trough that birthed Cyclone Alfred actually spawned two other cyclones, Rae and Seru, which moved east, while Alfred took a path south-east and off the Queensland coastline. This year was the Coral Sea's warmest summer on record. Data from the Bureau of Meteorology shows ocean temperatures off Brisbane and to the south have been between 0.5C and 1C hotter than normal in recent days. On Tuesday, Tropical Cyclone Alfred was far enough south to come into contact with a weather system common at lower latitudes – an area of high pressure – that grabbed Tropical Cyclone Alfred and pushed it west towards the south-east Queensland coastline. On Wednesday, Cyclone Alfred was moving through this area as it approached the coast, where it was expected to cross on Friday morning as a category two system. There are three main impacts that scientists and authorities are concerned about from Tropical Cyclone Alfred's move to the Queensland coast: damage from extreme winds, flooding from intense rain, and damage at the coast from storm surge and damaging waves. A warmer atmosphere can hold more water that can fall as rain, and generally, the atmosphere can hold 7% more moisture for each 1C of warming. But rainfall intensities can be greater than this because, as raindrops form, they also release energy into a system. Dr Andrew Dowdy, an associate professor and expert on tropical cyclones at the University of Melbourne, and his colleagues have advised that for Australia, infrastructure or building planners should consider that each degree of warming could increase rainfall by as much as 15%. Dowdy points to several characteristics from climate change that can make the impacts from Cyclone Alfred worse. 'Climate change has heated the oceans so the dice [are] loaded for a greater chance of hot water around Australia, like what we saw this summer,' he said. 'These hot ocean temperatures can help supercharge tropical cyclones with more extreme rainfall and flood risks.' When ocean heat up from climate change, they expand, pushing up sea levels. The melting of ice attached to land like ice sheets and glaciers also raises sea levels. Dowdy sea levels around the globe have already risen by 20cm due to climate change, 'which can make damages worse when storms like Cyclone Alfred hit.' 'This includes more severe flood risks in tidal waterways like around the Gold Coast and the Brisbane River, as well as more severe coastal erosion.' Read more of Guardian Australia's Tropical Cyclone Alfred coverage: Sign up to Breaking News Australia Get the most important news as it breaks after newsletter promotion When and where is Cyclone Alfred likely to hit? How to prepare for a cyclone
The Guardian
28-02-2025
- Climate
- The Guardian
Weather tracker: six cyclones swirl simultaneously in southern hemisphere
An uncommon meteorological event unfolded on Tuesday when six named tropical cyclones were active simultaneously in the southern hemisphere, several in close proximity to each other. Three developed in the south-west Pacific. Severe Tropical Cyclone Alfred formed on 20 February in the Coral Sea to the north-east of Australia, reaching an intensity equivalent to a category-4 hurricane on Thursday with sustained winds of 105mph (170km/h) and gusts at about 140mph. Alfred is tracking south, moving roughly parallel with the Queensland coast, and warnings have been issued for strong winds and rough seas. Though it is not expected to make landfall, the Australian Bureau of Meteorology is monitoring Alfred as it remains uncertain how close it will pass by the coast. Farther east in the south-west Pacific, there were two shorter-lived storms, Rae and Seru, which reached a maximum intensity equivalent to a category-2 hurricane. Tropical Cyclone Rae developed just north of Fiji on 22 February before travelling south across the island. Tropical Cyclone Seru formed on 24 February over the southernmost Solomon Islands, travelling southwards and passing to the east of Vanuatu and New Caledonia. While Seru remained offshore, Rae caused significant damage to some Fijian islands, owing to a combination of flood waters from heavy rain, gusts of about 100mph, and huge waves. Severe Tropical Cyclone Bianca, which formed in the Timor Sea to the north-west of Australia, was active between 18 and 27 February in the south-east Indian Ocean, during which time it travelled west before veering south, allowing it to curve around the continent without making landfall. This cyclone had a peak intensity the equivalent of a category 3 hurricane. And in the south-west Indian Ocean, two more cyclones are bracketing Madagascar, both of which developed on Monday. The category 3-equivalent Intense Tropical Cyclone Garance formed to the north-east of Madagascar and travelled south. After passing to the west of Mauritius, Garance will affect the French island of Réunion on Friday, with 120mph gusts and the potential for up to 600mm of rain. Meanwhile, the category 1-equivalent Severe Tropical Storm Honde formed in the Mozambique channel and travelled south-east, where it is skirting the southern tip of Madagascar. Though infrequent, it is far from unusual for this many named storms to exist concurrently. A far rarer occurrence is for this many to occur within a single ocean basin. The Pacific Ocean has recorded six simultaneous named storms on just one occasion, in August 1974, while the Atlantic record is five, set in September 1971.
The Guardian
27-02-2025
- Climate
- The Guardian
Satellite image captures three tropical cyclones spinning in the South Pacific at once
Three tropical cyclones are churning in the South Pacific, an occurrence that scientists say is unusual. Tropical cyclones Rae, Seru and Alfred are all spinning as the region's cyclone season, which starts in November and ends in April, reaches its peak. 'Certainly it is a very busy period for the South Pacific and three tropical cyclones is a lot to happen at once, but not unprecedented,' said Brian Tang, an atmospheric science professor at University at Albany. The last time three such storms occurred in the South Pacific was January 2021 when Lucas, Ana and Bina were churning simultaneously, Tang said. Rae formed on Friday north of Fiji and brought whipping winds and heavy rain that damaged fruit trees, according to local reports. Alfred developed in the Coral Sea on Monday and is expected to bring flooding rains to Queensland, Australia, this weekend. Seru became a cyclone on Tuesday and is expected to track near the island nation of Vanuatu but remain offshore. Gabriel Vecchi, a climate scientist at Princeton University, noted evidence of what's called a Madden–Julian Oscillation — a fluctuation in the atmosphere that results in a blob of rising air and rainfall that circles the globe and lasts for 30 days or longer. He said it seems to be tracking over the south-west Pacific in a way that could enhance cyclone activity. 'The atmosphere is chaotic. There's a lot of natural fluctuation in it … we need to be open to the possibility that factors that are beyond our ability to predict might have led to these three cyclones at the same time,' said Vecchi. Tropical storms are called cyclones when they happen in the south-west Pacific and hurricanes when they form in the north Atlantic, but they are essentially the same weather event.
CBS News
26-02-2025
- Climate
- CBS News
3 tropical cyclones churn in the South Pacific in unusual occurrence
Three tropical cyclones are spinning in the South Pacific, an occurrence that scientists say is unusual. Tropical cyclones Rae, Seru and Alfred are all churning as the region is in the peak of a season that starts in November and ends in April. The storms are called cyclones when they happen in the Southwest Pacific and hurricanes when they form in the North Atlantic, but are essentially the same phenomenon. "It's not incredibly unusual to have three hurricanes simultaneously in the month of September in the North Atlantic," said Brian Tang, an atmospheric science professor at University at Albany. "Certainly it is a very busy period for the South Pacific and three tropical cyclones is a lot to happen at once, but not unprecedented." The last time three such storms occurred in the South Pacific was January 2021 when Lucas, Ana and Bina were churning simultaneously, though it's not clear if Bina officially reached Category 1 status, Tang said. Rae formed Friday north of Fiji and brought whipping winds and heavy rain that damaged fruit trees, according to local reports. Alfred developed in the Coral Sea on Monday and is expected to bring flooding rains to the northeast Australia state of Queensland this weekend. Seru became a cyclone on Tuesday and is expected to track near the island nation of Vanuatu but remain offshore. "The atmosphere is chaotic. There's a lot of natural fluctuation in it … we need to be open to the possibility that factors that are beyond our ability to predict might have led to these three cyclones at the same time," said Gabriel Vecchi, a climate scientist at Princeton University.
Nahar Net
26-02-2025
- Science
- Nahar Net
Three tropical cyclones swirl in South Pacific
by Naharnet Newsdesk 26 February 2025, 14:10 Three tropical cyclones are spinning in the South Pacific, an occurrence that scientists say is unusual. Tropical cyclones Rae, Seru and Alfred are all churning as the region is in the peak of a season that starts in November and ends in April. The storms are called cyclones when they happen in the Southwest Pacific and hurricanes when they form in the North Atlantic, but are essentially the same phenomenon. How unusual is this? "It's not incredibly unusual to have three hurricanes simultaneously in the month of September in the North Atlantic," said Brian Tang, an atmospheric science professor at University at Albany. "Certainly it is a very busy period for the South Pacific and three tropical cyclones is a lot to happen at once, but not unprecedented." The last time three such storms occurred in the South Pacific was January 2021 when Lucas, Ana and Bina were churning simultaneously, though it's not clear if Bina officially reached Category 1 status, Tang said. Where are these storms and have they caused damage? Rae formed Friday north of Fiji and brought whipping winds and heavy rain that damaged fruit trees, according to local reports. Alfred developed in the Coral Sea on Monday and is expected to bring flooding rains to the northeast Australia state of Queensland this weekend. Seru became a cyclone on Tuesday and is expected to track near the island nation of Vanuatu but remain offshore. What caused three cyclones at the same time? Scientists say that's hard to say, but any explanation starts with the high activity that's usual this time of year. Gabriel Vecchi, a climate scientist at Princeton University, noted evidence of what's called a Madden–Julian Oscillation — a fluctuation in the atmosphere that results in a blob of rising air and rainfall that circles the globe and lasts for 30 days or longer. He said it seems to be tracking over the southwest Pacific in a way that could enhance cyclone activity. "The atmosphere is chaotic. There's a lot of natural fluctuation in it … we need to be open to the possibility that factors that are beyond our ability to predict might have led to these three cyclones at the same time," said Vecchi.
