Compound occurrence of marine and atmospheric heatwaves with drought conditions over the Mozambique Channel and Madagascar Island

Record-breaking heatwaves, both atmospheric or marine, occur regularly throughout the world, leading to a variety of sectoral and societal impacts. According to the WMO, since 1970 there were more than 11 000 reported disasters attributed to these hazards globally, with just over 2 million deaths and US$ 3.64 trillion in losses. Heatwaves are among the top 4 disasters in terms of human losses during the 50-yr long period, with uneven impacts throughout the world.

Madagascar, which is well known for its vast biodiversity, and abundant and unique natural resources, has been affected by successive droughts and hot events with disastrous consequences for the agriculture sector, and consequently increasing food insecurity. During the last decades, climate change and environmental degradation contributed to an escalation of the ecosystem’s fragility, therefore decreasing, even more, food security in subsistence farming regions.

Considering that the association between higher temperatures and water scarcity increases the risk of food insecurity compared to the sole occurrence of individual hazards, it is very important to address extreme events on a compound approach, identifying synergies, driving mechanisms, and dominant atmospheric modes controlling single and combined hazards.

Here the focus is placed on a particularly sensitive region,  the Madagascar Island, which shows significant positive trends in heatwaves metrics over the period 1982–2022 (frequency, intensity, duration, and intensity composite index). The combined occurrence of both marine and atmospheric heatwaves and drought conditions along the Mozambique Channel and Madagascar relying on ERA5 reanalysis was also performed and ranked according to the referred metrics. Of the two zones considered, there is considerable differences between trends when addressing separately the northern and southern regions, particularly in the case of the intensity of marine and atmospheric heatwaves.  

 

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020- IDL ,  DHEFEUS - 2022.09185.PTDC and ROADMAP - JPIOCEANS/0001/2019.