Hurricanes - a result of Global Warming?

Climate Change impacts: Hurricanes

In 2004 alone, 9 hurricanes affected the United States causing an estimated US$42 billion dollars in damage.

Just one of these storms, Hurricane Ivan, destroyed 89% of the total housing stock in Grenada, with damages estimated to be nearly US$889 million, more than twice the value of Grenada’s Gross Domestic Product.

And then came 2005.

FIVE Records Broken by 2005 Atlantic Hurricane Season:
  • Most Named Storms
    26 named storms, exceeding the official name list and moving through the first 5 letters of the Greek alphabet. The United States National Hurricane Center had predicted a large year but estimated only 18-21.

  • Most Hurricanes
    14 became hurricanes, meaning that winds exceeded 119 km per hour (74 mph). The previous record was 12 hurricanes in one year.

  • Most Category 5 Storms
    5 storms had winds over 249 kph (155 mph).

  • Most Storms Hitting the United States
    4 storms made landfall.

  • Most Expensive Hurricane Damage
    Figures are still not final for the 2005 season, however Hurricane Katrina alone is already estimated at “over US$100 billion total losses” .

And it did not quite want to stop: Although the hurricane season officially ended on the last day of November, Hurricane Epsilon was still blowing in the Atlantic by December.
Satellite image / ©: NASA
Hurricane Katrina on the southern coast of the USA, August 2005
© NASA
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Thunderstorm on the outlying reefs Tutia Reef, Tanzania
© Meg GAWLER / WWF-Canon

Hurricanes - How does it work?


Sea surface temperatures have increased by 0.7°C since pre-industrial times alongside the warming of the atmosphere. They are projected to continue to increase through the 21st century and are likely to lead to an increase in the intensity and perhaps the frequency of hurricanes and tropical storms. Scientists also anticipate that rainfall from hurricanes and tropical storms will increase.

Recent scientific findings already show that there has been a substantial increase in net hurricane power, both in terms of longer storm lifetimes and intensity, over the last 30 years.

The rate of global mean sea level rise during the 20th century was between 1.7 mm per year and has accelerated to 3.0 mm pere year since 1993 (IPCC 2007). It is expected to rise even faster throughout the 21st century, resulting in a global mean rise of between 0.18 to 0.59 meters by 2100.  Sea level rise will make storm surges reach up higher onto land that so far was protected, with low-lying, coastal areas being at highest risk.

It has been suggested that a globally warmer world could result in an increase in the frequency of hurricanes and tropical storms. However, this is a moot point and historical data from the past several decades does not show an increased trend in the frequency of hurricanes and tropical storms.
What does it mean?

Even if the frequency of hurricanes does not change because of human-induced climate change, the increased intensity that has been measured and is expected to continue is likely to lead to an increasing risk in the occurrence of highly destructive category 5 storms. There can be no doubt that this will impact natural and human systems.

More powerful hurricanes will have stronger winds, larger storm surges, and heavier precipitation. The effect is an increased risk to human life, increased damage to infrastructure and coastal property, and more destruction and disturbance to coastal ecosystems such as mangroves, river deltas and coral reefs.
 / ©: WWF-Canon / Nigel DICKINSON
Climate change is increasing the intensity of hurricanes. The picture shows a child in Honduras, after Hurricane Mitch has wrecked havoc on the country in 1998.
© WWF-Canon / Nigel DICKINSON

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