Tropical storms, known as hurricanes in the Atlantic and Northeast Pacific, and typhoons in the Northwest Pacific, are colossal weather systems that draw their immense power from warm ocean waters. These rotating storms typically form in tropical regions where sea surface temperatures are at least 26.5 degrees Celsius down to a depth of 50 metres, providing the necessary heat and moisture to fuel their development. As warm, moist air rises, it cools and condenses, releasing latent heat that further warms the surrounding air, causing it to rise even more. This continuous cycle creates a low-pressure area at the surface, drawing in more air and moisture, leading to the characteristic spiralling cloud bands and intense rainfall.
The formation process requires several other specific atmospheric conditions, including low wind shear – a minimal change in wind speed or direction with height – which allows the storm to grow vertically without being torn apart. A pre-existing weather disturbance, such as a tropical wave, can act as the initial trigger for the system to begin organising. Once these conditions align, a tropical depression can form, which may then intensify into a tropical storm and, if conditions remain favourable, a hurricane or typhoon, characterised by sustained winds exceeding 74 miles per hour (119 kilometres per hour).
A significant body of scientific research indicates that climate change is playing a crucial role in making these powerful tropical storms stronger. As the Earth's oceans absorb over 90% of the excess heat generated by human-induced greenhouse gas emissions, sea surface temperatures are rising globally. This warmer water provides more energy for hurricanes and typhoons to develop and intensify, leading to higher wind speeds and increased rainfall rates. The Intergovernmental Panel on Climate Change (IPCC) has consistently highlighted the observed and projected increases in the proportion of intense tropical cyclones.
While the overall number of tropical storms globally may not see a dramatic increase, the proportion of those reaching the most intense categories (Category 3, 4, and 5) is projected to rise. Stronger storms mean greater potential for devastating impacts, including more extreme storm surges – an abnormal rise of water generated by a storm, over and above the predicted astronomical tide – which can inundate coastal communities. Furthermore, warmer air can hold more moisture, leading to an increase in the amount of rainfall associated with these storms, exacerbating flooding risks.
The implications of these changes are far-reaching. Coastal regions worldwide, home to millions of people, face increased threats from more powerful winds, torrential rain, and higher storm surges. The economic and social costs of recovery and rebuilding after such events are substantial, placing immense strain on infrastructure, emergency services, and local economies. Understanding the mechanisms behind these storms and their evolving characteristics is crucial for developing effective mitigation and adaptation strategies in a warming world.
Source: Intergovernmental Panel on Climate Change (IPCC)