A new study revealed that the world's oceans absorbed a record-breaking 23 zettajoules of heat in 2025, marking the eighth consecutive year of increasing ocean heat absorption. The research, published Friday in the journal Advances in Atmospheric Science, indicated a significant increase from the 16 zettajoules absorbed in 2024.

The study was conducted by a team of over 50 scientists from the United States, Europe, and China, who analyzed data on ocean heat content since 2018. Their findings showed a consistent upward trend, with 2025 setting a new high since modern measurements began in the 1960s. A joule, a standard unit of energy, is relatively small, but a zettajoule is one sextillion joules, illustrating the massive scale of energy involved. The 23 zettajoules absorbed in 2025 can be written as 23,000,000,000,000,000,000,000 joules.

The increasing ocean heat absorption is a critical indicator of climate change. Oceans act as a major heat sink, absorbing over 90% of the excess heat trapped by greenhouse gases. This absorption helps to regulate global temperatures, but it also has significant consequences for marine ecosystems, sea levels, and weather patterns. Warmer ocean temperatures can lead to coral bleaching, altered marine habitats, and more intense storms.

Scientists use sophisticated climate models and data analysis techniques to estimate ocean heat content. These models incorporate various factors, including sea surface temperatures, salinity levels, and ocean currents. The data is collected from a network of sensors, satellites, and research vessels around the world.

The continued increase in ocean heat absorption underscores the urgency of addressing climate change. Experts emphasize the need for reducing greenhouse gas emissions to mitigate the impacts of rising ocean temperatures. Future research will focus on improving climate models and understanding the complex interactions between the ocean and the atmosphere.