You may have noticed the sun is warmer than ever before. 2025 is shaping up to be a very warm year, on track to be one of the top five warmest on record. It has already set a record for the warmest January and experienced other record-warm months. The increasing warmth is not by human interference, it is due to a submarine volcano outburst up to 58 km, which brought water vapour in the stratosphere and mesoshere. The warmth might be caused by the chemical interaction of ozone with water vapour.

In the stratosphere, the region of the Earth’s atmosphere from 6 to 30 miles (10 to 45 kilometers) above the surface, the chemical compound ozone plays a vital role in absorbing harmful ultraviolet radiation from the sun. The ozone layer sits in the stratosphere between 15 km and 30 km above the earth and shields us and other living things from the sun’s harmful ultraviolet radiation.

The January 2022 eruption of Hunga Tonga Hunga Ha’apai in the Pacific Ocean was the largest volcanic eruption ever recorded. The submarine volcano in the Tonga archipelago in the Pacific Ocean began to become restless in December 2021. A first major eruption occurred on January 14, 2022, but the big bang came a day later, on January 15. A powerful explosion propelled seawater and volcanic material to an unprecedented height of 58 km. It is estimated that 150 million tons of water vapor were ejected into the stratosphere—about the size of 58,000 Olympic swimming pools.

In water, part of the ozone reacts directly as molecular ozone with dissolved solutes. Another part decomposes before solute reaction, catalyzed by hydroxide ions (OH−)(OH−) or by superoxide anion radicals O2 ⋅−O2⋅−​ liberated from reactions of molecular ozone with certain organic and inorganic compounds. This decomposition of molecular ozone results in the formation of the highly reactive secondary oxidant – the OH-radical. Hence, any degradation of a solute during ozonation will be a result of the solutes reaction with both molecular ozone and OH-radical.

Ozone in the stratosphere reacts chemically with water. This chemical reaction can deplete the stratospheric ozone layer. Further research into the chemical impact of the Hunga Tonga Hunga Ha’apai submarine volcanic eruption is necessary. It is unclear how long the effects of the enormous amount of water in the stratosphere last. For now, more caution is advised when exposing human skin to the sun.

Depletion of stratospheric ozone occured year after year over both hemispheres of the Earth. However, this phenomenon is more pronounced in the Southern Hemisphere (Antarctica) than in the Northern Hemisphere (Arctic). This is the case because the formation of the ozone hole is directly linked to the stratosphere’s temperature. Once temperatures drop below -78°C, polar stratospheric clouds tend to form, which exacerbate ozone depletion.

Dobson Units (DU) measure how much ozone is in the air above us. On a global scale, the average total ozone concentration is typically around 300 DU. Ozone levels tend to be higher near the poles and lower at the equator. Generally, the ozone hole is defined as the area for which ozone column values amount to 220 Dobson Units (DU. This is only apparent in the southern hemisphere. Today (October 17, 2025) the Southpole has 384 DU and the Northpole 125 DU.