What is it about?
The Hunga Tonga volcano erupted in January 2022 and sent enormous amounts of water vapour into the stratosphere. No such event has ever been observed, mean we do not have a precedent to estimate the climate impacts of the volcano. This study concentrates on the novel aspect of the volcano--the large amounts of water vapour in the stratosphere--and aims to answer questions like - how long will the water vapour stay in the stratosphere? - what climate and weather impact should we expect from the volcano? - how long will those effects be felt at the surface?
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Photo by Yosh Ginsu on Unsplash
Why is it important?
Volcanoes are generally known to cool the global climate. This is because they produce large amounts of aerosols which shade Earth's surface from the sun. The Hunga Tonga volcano produced some of these aerosols, but not a particularly large amount compared to other volcanic eruptions. However, water vapour in the atmosphere is a potent greenhouse gas--even more so when it reaches the cold stratosphere. This would imply a potential global warming, which would be in addition to carbon dioxide-induced warming and make the climate crisis even worse. This study is important because it tries to evaluate the potential impacts of volcanically produced stratospheric water vapour as a greenhouse gas. In addition, it provides an estimate of how long the effects might linger.
Perspectives
This study does not feature the words "Hunga Tonga" or "volcano" in the title. This is because it is what we call an "idealised" study, which only includes the stratospheric water vapour produced by the Hunga Tonga volcano, and neglects the aerosols and smoke produced by the volcano. It is our assumption--and this was later proven to be correct--that aerosols remain in the atmosphere for a much shorter time than the water vapour in the stratosphere, so that the water vapour component dominates over the longer term. And this is what the study is about. There are a few caveats with the study, the main one being that surface temperatures over the oceans are kept constant, and at average conditions. This means we do not include any effects of ocean variability such as El Nino or sea ice variability, both of which are important during the 2020s. Therefore, the study has to be read as a "single-forcing" study, meaning only the effect of water vapour in the atmosphere, and nothing else, has been included.
Dr Martin Jucker
Read the Original
This page is a summary of: Long-Term Climate Impacts of Large Stratospheric Water Vapor Perturbations, Journal of Climate, September 2024, American Meteorological Society,
DOI: 10.1175/jcli-d-23-0437.1.
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