Sekar Ramdanira Gunawan

1. Introduction The phenomenon of global warming due to increasing anthropogenic activities in recent decades has had a broad impact, especially on the Earth’s climate [1]. The Intergovernmental Panel on Climate Change (IPCC) in its fourth assessment report (AR4), states that changes in global average surface temperature due to atmospheric carbon dioxide concentrations are in the range of 2–4.5 °C [2].

4. Summary and Conclusions This study assesses the characteristics of MHWs, including their frequency, maximum intensity, and duration of occurrences in the Indonesian waters over the last 40 years (1982–2021), specifically during a 26-year warm phase of PDO (1982–2007) and a 14-year cold phase of PDO (2008–2021). The analysis reveals that the longest average duration of MHWs, ranging from 7 to 15 days, occurred during the cold phase of PDO.