New research from a collaborative team, including Texas A&M University atmospheric scientist Dr. Andrew Dessler, is exploring the climate impact of the 2022 Hunga Tonga volcano eruption and challenging existing assumptions. The mid-January 2022 eruption injected vast amounts of volcanic aerosols and water vapor into the atmosphere, presenting a unique scenario as a submarine volcano. It increased total stratospheric water content by about 10%.
Historically, large volcanic eruptions have led to significant cooling effects on the global climate by blocking sunlight with their aerosols. Initially, scientists speculated that the water vapor might account for the extreme global warmth in 2023 and 2024. However, the team’s research, published in the Journal of Geophysical Research: Atmospheres, reveals the opposite: the eruption contributed to cooling the Earth.
“Our paper pours cold water on the explanation that the eruption caused the extreme warmth of 2023 and 2024,” said Dessler. “Instead, we need to focus primarily on greenhouse gases from human activities as the main cause of the warming, with a big assist from the ongoing El Niño.”
The team’s paper, “Evolution of the Climate Forcing During the Two Years after the Hunga Tonga-Hunga Ha’apai Eruption,” includes insight and analysis from Dessler, first author Dr. Mark Schoeberl, and multiple NASA scientists. They analyzed NASA and NOAA satellite data to estimate the energy balance of the Earth’s climate system. Their analysis revealed that the eruption resulted in more energy leaving the climate system than entering it, thereby inducing a slight cooling effect.
According to Dessler, this research reinforces that human-induced greenhouse gas emissions are the primary driver of climate change. This focus is particularly relevant given ongoing debates about the causes of global warming.
Schoeberl emphasized the importance of continued investment in satellite-based stratospheric measurements. “Our understanding of the Hunga Tonga eruption is largely thanks to the investment in stratospheric satellite measurements by NOAA and NASA over the past two decades,” he said. “However, we need to be cautious about a potential ‘stratospheric data desert,’ as some of the most critical instruments are not being replaced.”
While this paper answers several important questions, Dessler acknowledges that it introduces new ones. For instance, the researchers highlighted some unresolved issues related to the Hunga Tonga eruption, such as the unexpectedly low levels of sulfur dioxide produced and the minimal impact on the 2023 ozone hole. The persistence of water vapor in the stratosphere beyond predicted levels also suggests much remains to be learned about stratospheric circulation processes.
As scientists work to resolve ongoing questions, Schoeberl says the team’s work highlights the critical need for continued research and precise data to tackle the challenges of climate change.