Tonga eruption may be causing this unexpected ozone hole

Experts bring to attention an early, larger ozone hole for 2023.
Sade Agard
Volcanic ash plume on January 16, 2022 due to eruption of Hunga Tonga-Hunga Haʻapai taken by astronaut aboard the International Space Station (ISS).
Volcanic ash plume on January 16, 2022 due to eruption of Hunga Tonga-Hunga Haʻapai taken by astronaut aboard the International Space Station (ISS).

NASA Earth Observatory 

Scientists are observing the formation of the ozone hole over Antarctica much earlier than usual this year, sparking warnings of potential consequences for the Southern Ocean and Antarctic sea ice. 

Satellite data from the European Centre for Medium-Range Weather Forecasts (ECMWF) reveals the premature appearance of the ozone hole, which could become larger than average in 2023. 

As reported in a recent paper published in ESS Open Archive (yet to be peer-reviewed), the larger-than-normal hole could be due to atmospheric changes resulting from the eruption of the Tonga volcano in 2022.

The Antarctic ozone hole

"Starting in August is certainly very early...We don't usually expect that," said co-author Dr. Martin Jucker, a lecturer at the Climate Change Research Centre at the University of New South Wales.

Typically, the ozone hole begins forming towards the end of September, peaks in October and closes by November or December.

The Antarctic ozone hole is a recurring thinning of the ozone layer in the stratosphere, comprised of ozone molecules that absorb harmful ultraviolet radiation from the sun. 

Over time, the ozone hole has gradually recovered due to international efforts, including the 1989 Montreal Protocol that significantly reduced ozone-depleting chemicals.

However, the eruption of the Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022, released an extraordinary amount of water vapor into the stratosphere, disrupting the natural ozone-regulating processes. 

The authors explained in their paper that this influx of water vapor resulted in ice clouds forming, facilitating the accumulation of ozone-depleting molecules.

They highlighted their concern about the potential impact of the ozone hole on Antarctic sea ice, which has reached record lows in recent years. 

The increased penetration of UV radiation through the weakened ozone layer could contribute to ice melt and further warming of the Southern Ocean.

Jucker noted that increased UV radiation reaching Antarctica and the Southern Ocean has more energy for ice melting. The ocean turns dark blue instead of reflective white with reduced sea ice. 

“There is a risk that the Southern Ocean would then heat up even more and then indirectly melt more ice because the water next to the ice is warmer," he said. 

The Tonga Volcano

The eruption of the Tonga volcano is expected to have lasting impacts, including higher surface temperatures in various regions of the world.

While this effect is temporary compared to the long-lasting impact of greenhouse gas emissions, the study highlights the interconnectedness of natural events and climate change.

As scientists monitor these developments closely, the early formation of the ozone hole serves as a reminder of the delicate balance between various atmospheric factors and their influence on the environment and climate.

The complete study was published in ESS Open Archive on August 4 and can be found here.

Study abstract:

The amount of water vapor injected into the stratosphere after the eruption of Hunga Tonga-Hunga Ha'apai (HTHH) was unprecedented, and it is therefore unclear what it might mean for surface climate. We use climate model simulations to assess the long-term surface impacts of stratospheric water vapor (SWV) anomalies caused by volcanic eruptions. The simulations show that the SWV anomalies lead to strong and persistent warming of Northern Hemisphere landmasses in boreal winter, and austral winter cooling over Australia. Thus, SWV forcing from volcanic eruptions like the one from Hunga Tonga-Hunga Ha'apai can have surface impacts on a decadal timescale. We also emphasize that the surface response to SWV anomalies is more complex than simple warming due to greenhouse forcing and is influenced by factors such as regional circulation patterns and cloud feedbacks. Further research is needed to fully understand the multi-year effects of SWV anomalies and their relationship with climate phenomena like El Niño Southern Oscillation.

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