Washington DC, Dec. 4 -- This year's ozone hole over Antarctica ranked among the smallest since the early 1990s, reflecting steady progress from decades of global action under the Montreal Protocol.

Declining chlorine levels and warmer stratospheric temperatures helped limit ozone destruction. Scientists say the layer remains on track to recover later this century.

Scientists from NOAA and NASA report that this year's ozone hole over Antarctica is the fifth smallest seen since 1992, the year that the Montreal Protocol, a landmark international agreement to phase out ozone-depleting chemicals, began to take effect.

During the peak of the 2025 ozone depletion season, from September 7 through October 13, the ozone hole covered an average ...