Hurricanes to Deliver a Bigger Punch to Coasts

Flood waters cover large tracts of land in Mozambique after cyclone Idai made landfall.
© World Food Programme.

Cyclone Idai death toll might rise to more than 1,000 people.

When tropical cyclone Idai made landfall near Beira, Mozambique on March 14, it was called possibly the the worst weather-related disaster to hit the southern hemisphere. The massive, horrifying, storm caused catastrophic flooding and widespread destruction of buildings and roads in Mozambique, Zimbabwe and Malawi. Mozambique’s President Filipe Nyusi feared the death toll might rise to more than 1,000 people.

Cyclones, also known as hurricanes or typhoons, can take thousands of lives and cause billions of dollars in damage. They generate large ocean waves and raise water levels by creating a storm surge. The combined effects cause coastal erosion, flooding and damage to anything in its path. There is considerable uncertainty in predicting trends in extreme weather conditions 100 years into the future. Some computer simulations suggest possible changes in these storms due to climate change.

Cyclone Idai © NOAA

Although other storms have hit this African coast in the past, the storm track for cyclone Idai is fairly rare. Warmer-than-usual sea-surface temperatures were directly linked to the unusually high number of five storms near Madagascar and Mozambique in 2000, including tropical cyclone Eline. Warmer ocean temperatures could also be behind the intensity of cyclone Idai, as the temperature of the Indian Ocean is 2 C to 3 C above the long-term average.

Regardless of changes to the climatic conditions that cause hurricanes to form and intensify, the fact is that these storms already occur frequently. Each year, 80 to 100 tropical storms occur globally. Of these, 40 to 50 are hurricanes, with 10 to 15 classified as major hurricanes.

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© Ryan P. Mulligan, professor, Civil Engineering, Queen’s University.