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Tuesday, June 30, 2026

Water Vapor Worries

The Ozone Layer

[CC image, credit: nptel.ac.in ]

The Atmosphere can be divided into layers. The Troposphere is the layer that is closest to the surface. When rising up in the Atmosphere, the next layer up is the Stratosphere. The next layer up is the Mesosphere and the fourth layer from the bottom is the Thermosphere.

The temperature rises or falls in a different way in each of these layers, as illustrated by the red line in the image CC from archive.nptel.ac.in on the right and the scale on the bottom.

The ozone layer is located in the lower stratosphere at an altitude of 15 to 35 km or 9 to 22 miles above the Earth's surface, with the highest concentrations usually peaking around 25 km. This altitude corresponds with a pressure level of 100 to 10 mb or hPa.

The ozone layer absorbs 97% to 99% of the Sun's medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which otherwise could cause severe damage to life on Earth.

Water vapor rising over Antarctica

The image below shows a temperature anomaly forecast for July 3, 2026. At this time of year very little sunlight is reaching Antarctica, so the temperature over Antarctica can get very low. At the same time, global warming has increased sea surface temperatures and this also keeps air temperatures over water relatively warm. The difference in temperature strengthens wind patterns from the Southern Ocean to Antarctica, which can lead to atmospheric rivers moving toward Antarctica, carrying water vapor and heat from the Southern Ocean to Antarctica.

The red color on the above image indicates high temperature anomalies over Antarctica. The dark blue areas indicate where snow has fallen over the sea ice around Antarctica and over the interior of Antarctica.

Much of the water vapor will fall out of the air as precipitation, in the form of rain or snow. However, some of the water vapor will remain in the air, since each 1°C rise in temperature will increase the capacity of the atmosphere to hold water by 7%. This extra water vapor increases temperatures, since water vapor is a strong greenhouse gas.

Furthermore, the extra water vapor can rise up and moisten the atmosphere up to and above the ozone layer. The combination image below shows relative humidity on June 30, 2026 at 01:00 UTC, with relative humidity reaching up to 100% at surface level (left), up to 100% at 70 mb or hPa (center), and up to 23% at 10 mb or hPa (right).

The threat is further illustrated by the image below, which shows precipitable water anomalies on June 30, 2026.

Damage to the Ozone Layer

[ from earlier post ]

Increases in stratospheric water vapor are bad news, as they not only speed up global warming but also lead to loss of stratospheric ozone, as Drew Shindell pointed out back in 2001.

It has long been known that deterioration of the ozone shield increases ultraviolet-B irradiation, in turn causing skin cancer.

Research (see box right) suggests that, millions of years ago, it could also have led to loss of fertility and consequent extinction in plants and animals.

Water vapor reaching stratospheric altitudes causes ozone depletion, as James Anderson describes in a 2017 paper and discusses in the short 2016 video below.

[ from earlier post ]

The situation looks set to deteriorate further. As more snow falls over Antarctica, the sea surface of the Southern Ocean increases in salinity, which speeds up melting of sea ice, as discussed in earlier posts such as this one. The extra water vapor and increased melting of sea ice both strongly accelerate the temperature rise, while water vapor that reaches the stratosphere and, as discussed above, also causes damage to the ozone layer.

Conclusion

The situation is dire and unacceptably dangerous, and the precautionary principle necessitates the danger to be acknowledged, while facilitating rapid, comprehensive and effective action to reduce the damage and to improve the outlook, where needed in combination with a Climate Emergency Declaration, as described in posts such as in this 2022 post and this 2025 post, and as discussed in the Climate Plan group.