Ocean heat content

What it is

The map is the NOAA NCEI yearly ocean heat content anomaly for 0-700 m in 2025. The number is 10¹⁸ joules in each 1° cell, calculated from temperature profiles. NCEI also publishes a 0-2000 m series. NASA and Climate.gov explain the global total over time. Mercator Ocean offers a European view of the same idea.

Why it matters

About 90 percent of the excess heat in the climate system is stored in the ocean (IPCC AR6). Sea-surface temperature describes only the top. This map shows where the upper 700 metres held more or less heat than the long-term reference in 2025.

How to read it

The colour is the 2025 anomaly in the upper 700 metres. It is not sea-surface temperature and not the 0-2000 m layer. Deeper layers have been measured well for a shorter time, with the strongest coverage since the Argo float era. NASA and Climate.gov show the global total as a time series.

Sources

• NOAA NCEI: Ocean Heat Content, Salt Content, and Sea Level Anomalies
• NASA: Ocean heat vital signs
• NASA: Ocean heat content vital signs (alternate path)
• Climate.gov: Ocean heat content explainer
• Mercator Ocean: Ocean heat content (optional secondary)
• IPCC SROCC hub (assessment framing)
• IPCC AR6 WG1 report

Open source map →