At a glance
Twenty-year mean: about 11.7 ZJ/yr (CI 340 to 402 TW). Annual gains vary with El Niño and La Niña. The published ±8 ZJ margin applies only to the gain from 2024 to 2025. Pace expressed in Hiroshima equivalents (62.76 TJ) per second.
Full chain (sun → EEI → ZJ → bombs/s): Methods § orders of magnitude →
News · July 2026
Oceans break a July sea-surface heat record
According to the Copernicus (C3S) monthly bulletin, the extra-polar ocean surface temperature (60°S–60°N) reached 20.96 °C in July 2026, a record for July (previous: 20.89 °C in 2023). Global surface air was at 16.90 °C, 1.47 °C above 1850–1900. In June, Copernicus had already reported daily records, up to 21.0 °C on 21 June according to Copernicus Marine.
This signal does not replace the lab's OHC data: sea surface temperature (SST) measures the ocean skin, while OHC quantifies energy accumulated through ocean volume. Together, they describe the same dynamic: an ocean absorbing and returning more energy to the climate system.
Primary source and SST/OHC distinction detailed in the Methods.
Why the Hiroshima bomb as a unit?
The bomb dropped on Hiroshima in August 1945 is one of only two ever used in real conditions. Its destructive power is anchored in collective imagination, consciously or not. We know the energy it released (about 62.76 TJ): it offers a concrete reference for otherwise abstract scales.
Climate warming is expressed in zettajoules — scales so vast that few people can grasp them intuitively. Climatologists often use the « Hiroshima bomb » equivalent to turn an energy flux into an immediate mental image.
Important: in this tool, each « bomb » denotes a quantity of thermal energy absorbed by the ocean, not an explosion.