Trend in global ocean heat content into different depth layers from 1940 to 2050

Abstract Oceans are crucial to Earth’s climate regulation and Earth’s energy, water, and carbon cycles, significantly affecting human society. Ocean heat content (OHC) is a critical indicator of global warming, as the ocean absorbs over 90% of excess heat trapped by greenhouse gases. This heat storage delays atmospheric warming but drives stronger storms, shifts ocean currents, and intensifies marine heatwaves. Understanding changes in OHC and monitoring them at the surface and various depth layers are becoming more and more crucial as global warming picks up speed. This study models and forecasts global monthly OHC time-series data within the 0–700 m, 0–2000 m, 0–6000 m, 700–2000 m, and 2000–6000 m depth layers until 2050 using the seasonal autoregressive integrated moving average (SARIMA) model. Initially, the global monthly OHC data set for all depth layers was analyzed from 1940 to 2023. Monthly and annual forecasts are then created until 2050. Results reveal that the SARIMA models exhibit coefficient of determination (R 2 ) values greater than 0.9972 and root mean square error (RMSE) values less than 5.3 Zetajoules (ZJ), and that they also accurately predict the trends and variability of the OHC data. By 2050, the global OHC anomalies relative to the 2006–2015 average in the 0-700, 0-2000, 0-6000, 700–2000, and 2000–6000 m depth layers are projected to reach 373 ZJ, 477 ZJ, 564 ZJ, 100 ZJ, and 95 ZJ, respectively.