---
title: "Antarctic ozone hole grows to its largest in a decade; NASA ranks 2026 seventh biggest in 48 years"
url: https://badiyaa.com/antarctic-ozone-hole-2026-largest-decade/
published: 2026-11-12T10:28:00+00:00
modified: 2026-11-12T10:28:00+00:00
section: Science
publisher: Badiyaa
---

# Antarctic ozone hole grows to its largest in a decade; NASA ranks 2026 seventh biggest in 48 years

The 2026 Antarctic ozone hole averaged 9.6 million square miles, NASA and NOAA said, ranking seventh largest in 48 years and the biggest in a decade.

Earth’s ozone hole over Antarctica opened wider in 2026 than in any year since 2015. Averaged over the peak depletion window of September 7 to October 13, it spread across about 9.6 million square miles (25 million square kilometers), [NASA and the National Oceanic and Atmospheric Administration (NOAA) reported](https://science.nasa.gov/earth/2026-ozone-hole/). That makes it the seventh largest in 48 years of records.

On September 18, its biggest single day, the hole reached 27.1 million square kilometers, or 10.5 million square miles. A NASA video summary says that figure is [about 90% of the biggest hole ever observed](https://svs.gsfc.nasa.gov/vis/a010000/a015100/a015116/script_39769_00.html), the one that formed in September 2000.

## How the agencies measured it

Satellites have watched the ozone layer since 1979. This year’s numbers drew on instruments aboard NASA’s Aura satellite, NOAA-20, NOAA-21 and the jointly run Suomi NPP spacecraft. On the ground, NOAA staff at the South Pole launched balloons carrying ozonesondes, small instruments that sample ozone as they climb. The hole is defined as the region where ozone falls below 220 Dobson units, the standard measure of ozone concentration.

## A stubborn vortex did the damage

The agencies point to weather in the stratosphere, not to a rise in pollution. Every southern winter a belt of fierce winds, the polar vortex, traps frigid air over Antarctica. In that cold, chlorine and bromine released from human-made chemicals strip away ozone once spring sunlight returns.

Paul Newman, a University of Maryland, Baltimore County senior scientist who has led NASA’s ozone team at Goddard Space Flight Center for years, said the holes have recently been forming later in the season, a sign of healing. This year, though, “an unusually powerful polar vortex has extended ozone depletion in the Antarctic this season, allowing the hole to grow to proportions we haven’t seen in a decade,” he said.

Amy Butler of NOAA’s Chemical Sciences Laboratory explained why. Large atmospheric waves that usually rise from below and break the vortex apart were especially feeble in August and September, so its strongest winds sat several degrees of latitude farther from the pole than normal. That left a bigger zone cold enough for ozone loss.

## Wide, but not deep

Size is only half the picture. Balloon readings over the South Pole bottomed out at 105 Dobson units on October 17. The record low there was 92 Dobson units, set in October 2006. Newman added that the hole could have been 1 to 2 million square miles larger still if ozone-destroying chemicals were as plentiful today as they were at their 2000 peak.

## Putting 9.6 million square miles in context

The 2026 average area is about two and a half times the size of the United States, which covers roughly 3.8 million square miles (9.6 divided by 3.8 is about 2.5). The single-day peak also lets us estimate the 2000 record: if 27.1 million square kilometers is 90% of it, the record hole covered roughly 30 million square kilometers (27.1 divided by 0.9). The last comparable year was 2015, when a [NOAA satellite summary](https://commons.wikimedia.org/wiki/File:Ozone_Hole_Over_Antarctica_Reaches_Annual_Maximum_(24270792702).jpg) logged a peak of 28.2 million square kilometers on October 2.

## Limits of a single season

One big year does not reverse the trend. The 1987 Montreal Protocol committed countries to phase out ozone-depleting substances, and Stephen Montzka of the NOAA Global Monitoring Laboratory said chlorine from those compounds in the Antarctic stratosphere has fallen by about a third compared with 1980s levels. The catch is time: chlorofluorocarbons once used in refrigerators, air conditioners and building insulation keep seeping from old products and landfills for decades. Year-to-year size depends heavily on vortex weather, so a single season says little on its own.

Antarctica has been busy on our pages lately, from [iceberg A-81 stalling off South Georgia](https://badiyaa.com/iceberg-a-81-south-georgia-shelf/) to a [Swiss trial that shielded glacier ice with sheep’s wool](https://badiyaa.com/swiss-glacier-wool-blankets-plastic-fleece/). For the ozone layer, scientists estimate full recovery of the Antarctic hole by the 2070s, and the next annual peak arrives in September 2027.

*Image: NOAASatellites, Public domain via Wikimedia Commons*

*This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*