TROPICAL CYCLONE ILSA

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Picture Courtesy: https://www.downtoearth.org.in/news/climate-change/climate-crisis-impact-australia-s-most-intense-cyclone-wiped-out-90-of-seabirds-on-an-island-96681

Context: Climate change has led to a devastating impact on seabird populations in Australia, with 90% of seabirds wiped out on Bedout Island after Tropical Cyclone Ilsa struck in April 2023.

Key Highlights

• Tropical Cyclone Ilsa with sustained winds of 230 kilometres per hour, caused extensive damage, damaged coastal vegetation in Australia.
• Recently, a study published in the journal Nature Communications found that three species of seabirds, including Masked Boobies, Brown Boobies, and Lesser Frigatebirds, perished in the storm. Only 40 breeding Masked Boobies were recorded on the island 15 weeks later.
  • Seabirds play a crucial role in the ecosystem, connecting marine and terrestrial ecosystems by transporting marine-derived nutrients to terrestrial areas through guano deposition.
  • The study warns that the frequency and intensity of such storms are reaching a threshold at which the seabird populations on Bedout Island may no longer be able to recover.
• Bedout Island and Ashmore Reed are vital areas for bird biodiversity, accounting for a significant portion of the world's Lesser Frigatebird and Brown Booby populations. An aerial survey conducted after Cyclone Ilsa passed found no living seabirds on the island.
• The study also discovered some unusual behaviour in the birds. Contrary to expectations, the seabirds did not flee the island during the cyclone.
  • Carcasses of birds, such as the Lesser Frigatebird, were found in their nesting sites, which is unusual as these birds are known to have the ability to forecast cyclones and alter their behaviour accordingly.
  • The strong bond between adult birds and their chicks may have contributed to adults' reluctance to abandon their nests. However, this behaviour still needs further explanation.

Tropical Cyclones

• Tropical cyclones, also known as hurricanes, typhoons, or cyclones depending on their location, are intense storm systems characterized by a low-pressure centre, strong winds, and organized thunderstorms.

Formation and Characteristics

• Formation Over Warm Waters: Tropical cyclones typically form over warm ocean waters with temperatures above 26.5°C. The warm water provides the energy source through evaporation and condensation processes.
• Structure: They have a well-defined centre called the eye, surrounded by bands of intense thunderstorms with heavy rainfall and strong winds. The system is powered by the release of latent heat from condensation within the thunderstorms.
• Size: Tropical cyclones can range in size from approximately 100 to 2,000 kilometres in diameter, covering a large area as they develop and move.
• Rotation: The rotation of tropical cyclones is influenced by the Earth's rotation, known as the Coriolis effect, which causes air to spiral inward towards the low-pressure centre.

Impact of Climate Change

• Increased Intensity: Warmer ocean temperatures due to climate change provide more energy for tropical cyclones, potentially increasing their intensity. This can lead to stronger winds, heavier rainfall, and more destructive storm surges.
• Shift in Distribution: Climate change may alter the geographic distribution of tropical cyclones. There is evidence suggesting that cyclones might reach farther from the equator and possibly impact regions that traditionally have not experienced such storms.
• Frequency Changes: While there is ongoing research, the overall frequency of tropical cyclones globally may not increase significantly with climate change. However, there could be changes in the distribution of storm intensity, with stronger storms becoming more common.
• Regional Variability: Different ocean basins experience varying impacts of climate change on tropical cyclones. For instance, the Atlantic Ocean and North Pacific are expected to see more pronounced changes compared to the South Pacific or Indian Ocean due to regional climatic influences.

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Source:

Down To Earth

Wikipedia