In 2019, out of 308 natural disasters, 59 were storms making them the second biggest natural hazard after floods (IFRC 2020). Storms affected 37 countries and killed 2,764 people, impacting 31.9 million people. More than half (52%) of all disasters triggered by storms occurred in Asia, followed by 26% in the Americas. In Oceania, 51% of disasters were triggered by tropical storms. In the Americas, 33% of disasters were storms (tropical storms, tornadoes and blizzards), affecting Central America and the Caribbean in particular. Storms not only lead to loss of life but also disruption in economic and social activities, as well as destruction of homes of climate vulnerable people. Storm events have been relatively stable in number and have even decreased slightly as a proportion of all extreme weather events during the past three decades, however frequency of intense storms (category 4 and 5) have increased substantially.
Tropical cyclones combined with higher sea levels can result in higher storm surges: the deadly wall of water that storms often bring onto land as they make landfall. Extreme waves and storm surges are projected to increase across the Southern Ocean, tropical eastern Pacific and Baltic Sea, although they may decrease in the North Atlantic and Mediterranean Sea (IFRC 2020).
Mangroves are critical to reducing the impacts of storm surges. The mangroves’ effect on wave attenuation depends on the width of the mangrove belt (from sea to land) as well as its composition. Relatively narrow belts can reduce the height of wind and swell waves. A 2012 study of these waves (with an initial height of up to 70cm) found that belts 100 meters in width reduced wave height by 13 - 66% (McIvor et al 2012:3). Wider mangrove belts can also attenuate storm surges; rates of surge height reduction have been recorded at 4 - 48 cm per kilometer of passage through mangroves (Spalding et al. 2014: 51).
In addition to mangroves, a meta-analysis of coral reefs in the Indian, Pacific, and Atlantic Oceans revealed that on average, reefs dissipate 97% of wave energy that would otherwise impact shorelines. In their meta-analysis of 27 studies on coral reefs and wave attenuation in the Indian, Pacific, and Atlantic Oceans, Ferrario et al. (2014) compared the wave energy and height reduction by reef crests (the seaward barrier of the reef), the reef flat (the expanse of the reef), and the whole reef. Most of the energy is absorbed by reef crests (86%), although the width of the reef flat also makes a difference in wave energy and wave height reduction (for reef flats less than 1,000 meters wide). Dunes and shelter belts that act as wind breaks have also been known to reduce storm surge.
Source: IFRC. 2020. World Disasters Report 2020: Come Heat or High Water. Geneva: IFRC. URL: https://media.ifrc.org/ifrc/world-disaster-report-2020