INTRODUCTION
Tropical cyclones are given different names in different parts of the world (e.g. hurricane in the Atlantic, typhoon in the Pacific).
They are among the most devastating of natural disasters, and can cause immense loss of live and damage to infrastructure – as shown by Hurricane Katrina in the United States and Cyclone Nargis in Myanmar. In these storms, winds can reach 155 miles per hour 250 kilometers per hour) with heavy rainfall and storm surges.
These storms form over tropical waters when there is high humidity, light winds and warm sea temperatures. This often occurs from June to November for the northern hemisphere.
There is an intense scientific debate about whether climate change is increasing the threat these cyclones pose.
The Intergovernmental Panel on Climate Change noted in its most recent report (2007) that there has been an increase in the strength (but not in number) of hurricanes in the North Atlantic since 1970. It said this increase was correlated with an increase in sea surface temperatures.
For other regions, the IPCC said the scientific data was not adequate to draw strong conclusions.
Overall, it concluded that there was a more than 50 percent likelihood that human activities were contributing to an increase in the intensity of hurricanes.
More recent scientific studies have, however, produced some contradictory evidence. This has led some non-scientists to claim that the IPCC has exaggerated the threat.
The most recent major scientific study of the relationships between these storms and rising global temperatures attempted to draw a more comprehensive conclusion than the IPCC.
It concluded that studies consistently indicate that rising temperature caused by emissions of greenhouse gases “will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms”.
But it predicted that the number of tropical cyclones would fall, meaning that overall there would be fewer but more intense tropical cyclones as global temperatures rise.
Regardless of the exact effect of rising global temperatures on these big storms, coastal areas are likely to become more vulnerable to them because of rising sea levels.
SOLUTIONS
There is no way to stop the arrival of hurricanes as they are a natural phenomenon.
Solutions include the construction of more resilient buildings and better storm warning systems to protect people from these storms.
Other ways for countries and communities to reduce the threat from major cyclones include early warning systems and well-organized plans for evacuating coastal areas and ensuring the food, medicines and other supplies can be quickly delivered to affected areas.
There is some evidence that coastal mangrove forests can absorb some of the destructive energy of major storms and protect the communities that live behind the forests.
Vast areas of mangroves have been felled in recent decades to make way for coastal developments and shrimp farms, leaving these areas more prone to damage.
Countries such as Indonesia and Vietnam have begun replanting mangrove forests to create a protective coastal buffer.
REPORTING TIPS
The US Society of Environmental Journalists has a toolkit on hurricanes and tropical storms. It includes a wide range of sources of information and interviewees, most but not all of which are US-focused.
The US National Oceanic and Atmospheric Administration has a useful set of answers to frequently asked questions about hurricanes and cyclones.
Its National Hurricane Center, together with the Central Pacific Hurricane Center and the Joint Typhoon Warning Center provide accurate and up-to-date information about all tropical storms that could develop into full cyclones or hurricanes.
FURTHER READING
UK Met Office – tropical cyclones