Tonga eruption boosted the amount of water vapor in the stratosphere by over 5%

Scientists do not exactly know how this will affect climate change.
Ameya Paleja
Ash plume of the Tonga eruption as captured from the ISS
Ash plume of the Tonga eruption as captured from the ISS


On January 15, 2022, the Hunga Tonga-Hunga Ha’apai submarine volcano in the southern Pacific ocean reached the climax of the eruption that had begun almost a month ago, giving off powerful shockwaves that raised tsunami alarms in the region. A study published today estimates that the eruption raised atmospheric water vapor content by over five percent.

Soon after the Tonga eruption, reports suggested that it was way more powerful than the atomic bomb dropped on Hiroshima. The island nation of Tonga was cut off from the rest of the world and it was five weeks later that the internet could be restored. Over a period of time, normalcy seems to have returned to the island nation but the true impact of the eruption is still being determined by scientists.

Ejections from volcanoes

Volcanic eruptions send out vast amounts of gases and dust into the atmosphere. Primary among the gases are carbon dioxide and nitrogen. Since these gasses are abundant in the atmosphere, their impact on climate change is considered minimal.

Sulfur-containing gases are also shot up by volcanoes into the stratosphere, the second lowest layer of the atmosphere where they can chemically react to form aerosols and result in a decrease in surface temperatures and the destruction of ozone.

Injection of water vapor into the stratospheric layer is also estimated to have an impact on climate change but events that can cause such injections are rare. Even the largest eruptions in the past century only resulted in minor ejections of water vapor.

In August, Interesting Engineering reported that the eruption sent enough water into the atmosphere that could fill 58,000 Olympic-sized swimming pools. The research conducted by a team at NASA had estimated that 146 teragrams of water were injected into the atmosphere, increasing water vapor content by as much as 10 percent. Their research had, however, claimed that even large amounts of water vapor would have a negligible impact on climate change.

Impact on the environment

Researchers at the National Center for Atmospheric Research (NCAR) used high-altitude weather balloons and estimated the amount of water injected to be at least 50 teragrams, which could increase water vapor content in the stratosphere by at least five percent.

The researchers are of the view that this unprecedented injection of water vapor could contribute to stratospheric cooling and surface warming over the months to come. When compared to the injection of aerosols into the atmosphere, this event is likely to persist for longer, since gravitational settling ensures that the aerosols drop out of the stratosphere.

The NCAR research was published today in the journal Science.


Large volcanic eruptions, although rare events, can influence the chemistry and the dynamics of the stratosphere for several years after the eruption. Here we show that the eruption of the submarine volcano Hunga Tonga-Hunga Ha’apai on 15 January 2022 injected at least 50 teragrams of water vapor directly into the stratosphere. This event raised the amount of water vapor in the developing stratospheric plume by several orders of magnitude and possibly increased the amount of global stratospheric water vapor by more than 5%. This extraordinary eruption may have initiated an atmospheric response different from that of previous well-studied large volcanic eruptions.

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