The mystery surrounding the eruption of the Hunga Tonga volcano in January 2022 deepens. Contrary to initial expectations, this underwater eruption may have had a cooling effect on Earth's climate, challenging assumptions about its role in the recent extreme warming.
GOES-17 satellite images of an umbrella cloud generated by the Hunga Tonga-Hunga Ha'apai underwater eruption on January 15, 2022.
Credit: NASA Earth Observatory image by Joshua Stevens using GOES images courtesy of NOAA and NESDIS
Researchers from Texas A&M University, led by climatologist Dr. Andrew Dessler, have analyzed this eruption and its consequences. Unlike other major volcanic eruptions like Tambora in 1815 and Pinatubo in 1991, Hunga Tonga injected large amounts of water vapor into the stratosphere, increasing stratospheric water content by 10%.
Early speculations suggested that this water vapor, a potent greenhouse gas, could explain the record heat of 2023 and 2024. However, results published in the
Journal of Geophysical Research: Atmospheres reveal that the eruption actually contributed to Earth's cooling.
The researchers, including lead author Dr. Mark Schoeberl, used satellite data from NASA and NOAA to assess the Earth's climate system's energy balance. Their analysis shows that the eruption caused a higher energy output than input, thus inducing a cooling effect.
These findings highlight the importance of human-origin greenhouse gas emissions in global warming. Dr. Andrew Dessler emphasizes that anthropogenic greenhouse gases, supported by El Niño, remain the primary culprits of recent heat.
The research also underscores the importance of continued investment in stratospheric satellite measurements. According to Dr. Mark Schoeberl, understanding the Hunga Tonga eruption was made possible by these investments, but he warns of a potential "stratospheric data gap" in the future.
Despite the answers provided, many questions remain. The enigma of the low sulfur dioxide production during the eruption and its minimal impact on the 2023 ozone hole persists. The study stresses the need for ongoing research to better understand stratospheric circulation processes.