Cyclones in an SSP5-8.5 World

Two recent studies have highlighted the effects of climate change on tropical cyclones posing far-reaching and multifaceted consequences across the global ecosystems 

• First Study: Cyclones could become stronger and more disruptive if global warming follows a future climate scenario called SSP5-8.5.
• Second Study: Roughly half of the world’s mangroves will be at high to severe risk by 2100 due to changes in tropical cyclone frequency and sea-level rise.

Key Highlights of the Study 1

• Method: The CLIMADA (CLIMate ADAptation) open-source risk modelling platform was used to check the response of specific ecoregions around the world to shifts in tropical cyclone patterns between 1980-2017 and to projected shifts for 2015-2050. 

• Classification: Each terrestrial ecoregion is classified in 3 groups,
  • Resilient: Historically oft-exposed to cyclones and able to recover quickly
  • Dependent: Regularly disturbed by cyclones that also shape the area’s ecosystem dynamics
  • Vulnerable: Rarely disturbed by cyclones and recovering slowly when exposed to one.
• Findings: 
  • Expanding range of Cyclones: 290 of the world’s 844 ecoregions are already affected by tropical cyclones. The climate models revealed 200 more can be considered vulnerable and 26 to be resilient.
  • Less Recovery Time: In the resilient ecoregions, the time available to recover between storms could drop from 19 years in the 1980-2017 period to 12 years in the 2015-2050 period for high-intensity storms.
  • High Risk Areas:  East Asia, Central America, and the Caribbean will experience the bulk of these shifts. The models also found that Madagascar and parts of Oceania are increasingly at risk.
  • Shifting of Cyclone Belts: Tropical cyclone belts could shift away from the equator  to higher-latitude regions bringing new cyclone activity and exposing ecosystems there to unadapted threats.

Key Highlights of Study 2

• Method: The study used a probabilistic spatially explicit risk index (a number that simultaneously measures the odds of an event and its expected spatial distribution).
  • A tropical cyclone model was used to simulate three scenarios: SSP2-4.5, SSP3-7.0, and SSP5-8.5.
• Findings: 
  • Increasing Risk for Mangroves Ecosystems: Up to 56% of mangrove areas worldwide could be at high to severe risk by 2100 in the SSP5-8.5 scenario.
    • Southeast Asia is expected to be the most affected, with 52-78% of its mangrove areas at such risk. Even in the less destructive SSP3-7.0 scenario, 97-98% of mangroves are at high to severe risk.
  • Risk for Ecosystem Services: Ecosystem services are also at risk including mangroves’ ability to sequester carbon, protect coasts, and improve fish stock.

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