New study disputes Hunga Tonga volcano’s role in 2023–24 global warm-up

A new study by a collaborative team led by atmospheric scientist Dr. Andrew Dessler of Texas A&M University explores the climate impacts of the 2022 eruption of Hunga Tonga volcano, questioning existing assumptions about the impacts along the way.

of Highlights of the two-day eventThe volcanic eruption that occurred in mid-January 2022 released large amounts of volcanic aerosols and water vapor into the atmosphere. Historically, Massive volcanic eruption Eruptions like Mount Tambora in 1815 and Mount Pinatubo in 1991 caused aerosols to block sunlight, resulting in significant cooling of the Earth’s climate.

But the eruption of Hunga Tonga created unique circumstances: for an undersea volcano, it spewed unprecedented amounts of water vapor into the stratosphere, increasing the total amount of water in the stratosphere by about 10%.

Water vapor is a powerful greenhouse gas, so Dessler said it was initially assumed it would be the cause of the extreme global warming in 2023 and 2024. But the team’s findings suggest that Published Wednesday, July 24 Journal of Geophysical Research: Atmosphereshows the opposite result: that the eruption, like other large-scale volcanic activity, actually contributed to the cooling of the planet.

The cooling effect of volcanic eruptions

The team’s paper, titled “Evolution of Climate Forcing Two Years Following the Hunga Tonga Hunga Ha’apai Eruption,” includes insights and analysis from Dessler, a professor in the Department of Atmospheric Sciences at Texas A&M University and director of the Texas Climate Research Center; lead author Dr. Mark Schobel, principal scientist at the Hamburg, Virginia-based Science and Technology Corporation; and several scientists at the National Aeronautics and Space Administration (NASA).

Their method involved analysing satellite data from NASA and the National Oceanic and Atmospheric Administration (NOAA) to estimate the energy balance of Earth’s climate system, including aerosols and water vapor. Their analysis revealed that the energy leaving the climate system from the eruption exceeded the energy coming in, causing a slight cooling effect.

“Our paper throws cold water on explanations that suggest an eruption caused the unusually hot weather in 2023 and 2024,” Dessler explained. “Instead, we should focus primarily on greenhouse gases from human activities as the main cause of the warming, with a major help from the ongoing El Niño event.”

Implications and future research

Dessler said the study has important implications for both scientists and the general public. By rejecting volcanic eruptions as the primary driver of recent warming, the team’s work strengthens Dessler’s argument that human-induced greenhouse gas emissions are the primary cause of climate change. This focus is especially important given the ongoing debate and misinformation about the causes of global warming.

Additionally, Schaubel said, the study highlights the importance of continued investment in satellite-based stratospheric measurements.

“Our understanding of the Hunga Tonga eruption owes much to NOAA and NASA’s investments in stratospheric satellite measurements over the past two decades,” Schoebel added, “but we need to be careful of a potential ‘stratospheric data desert’ because some of the most important instruments have not been replaced.”

The difficult road ahead

“The paper answers some important questions, but also raises new ones, Dessler acknowledged. For example, the researchers highlighted several unresolved issues related to the Hunga Tonga eruption, including the unexpectedly low levels of sulfur dioxide produced for such a violent eruption and the minimal impact the eruption had on the ozone hole in 2023.”

The 2023 ozone hole means that the ozone layer over Antarctica will be significantly thinner, allowing more harmful ultraviolet radiation to reach the Earth’s surface. water vapor Their presence in the stratosphere beyond that predicted by models suggests that there is still much to learn about stratospheric circulation processes.

As scientists work to answer ongoing questions and improve our understanding of the stratosphere, Schubel says his team’s work highlights the need for continued research and accurate data to address stratospheric challenges. climate change.