25 November 2022
Climate change turns up the heat on tropical cyclone formation
Published online 16 June 2022
Rising oceanic and surface temperatures could increase the number of intense tropical cyclones making landfall in countries including the United Arab Emirates and Iran.
Countries bordering the Gulf of Oman have historically been largely spared from the catastrophic damage associated with tropical cyclones. But an analysis at Khalifa University, in Abu Dhabi of the roots of two anomalous storms that ravaged the gulf coast suggests that climate change could make such deadly events more frequent.
Although tropical cyclone activity is common in the Arabian Sea, only two such storms have entered the Gulf of Oman since 1900: Gonu in 2007 and Shaheen in 2021. “The understanding of people in our region is that we are far from the danger of hurricanes compared to, for example, the east coast of the USA or to Southeast Asia,” says Diana Francis, an atmospheric scientist who led the study. But these ultra-rare events can be devastating. For example, Gonu caused 23 deaths and roughly US$216 million in damage along the Iranian coastline.
By analysing multiple sets of satellite data from the time between the formation and landfall of these two tropical cyclones, Francis's team were able to identify multiple factors that set them on their destructive course. Both storms were initially intensified by elevated oceanic temperatures, after which their course was established through the interplay between the subtropical jet stream and the ‘Arabian Heat Low’. The latter is a low-pressure system that forms as a consequence of the intense solar heat experienced by the Arabian Peninsula during the summer months. “We found that the Heat Low drags the cyclones in-land towards it,” says Francis.
As climate change continues to escalate, this region can expect to see increases in the heat and moisture that drive tropical cyclone formation. Francis anticipates that these rising temperatures will ultimately strengthen the Arabian Heat Low’s attraction of newly formed cyclones toward the Gulf of Oman.
“Increased risk to this region from tropical cyclones is not an idle concern, as it has been previously suggested that climate change has already caused such an increase,” says Kevin Walsh, an earth and atmospheric scientist at the University of Melbourne in Australia. “This study identifies some of the main mechanisms that drive these anomalous storms and will be useful in analysing predictions of tropical cyclone occurrence in this region.”
Francis's group will next investigate the influence of the dust storms that regularly form over the Arabian Peninsula, and which are known to generally influence cyclone activity.
Francis, D. et al. Key factors mModulating the threat of the Arabian Sea’s tropical cyclones to the Gulf countries. JGR Atmos. https://doi.org/10.1029/2022JD036528 (2022).