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

New research from a collaborative team featuring 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 about its effects in the process.

The remarkable two-day event, which occurred in mid-January 2022, injected vast amounts of volcanic aerosols and water vapor into the atmosphere. Historically, large volcanic eruptions like Tambora in 1815 and Mt. Pinatubo in 1991 have led to significant cooling effects on the global climate by blocking sunlight with their aerosols. However, Hunga Tonga's eruption presented a unique scenario: As a submarine volcano, it introduced an unprecedented amount of water vapor into the stratosphere, increasing total stratospheric water content by about 10%.

Because water vapor is a powerful greenhouse gas, Dessler says there was initial speculation that it might account for the extreme global warmth in 2023 and 2024. Instead, the results of the team's research, published Wednesday (July 24) in the Journal of Geophysical Research: Atmospheres, reveal the opposite: The eruption actually contributed to cooling the Earth, similar to other major volcanic events.

A Volcanic Eruption's Cooling Effect

The team's paper, titled "Evolution of the Climate Forcing During the Two Years after the Hunga Tonga-Hunga Ha'apai Eruption," includes insight and analysis from Dessler, a professor in the Texas A&M Department of Atmospheric Sciences and the director of the Texas Center for Climate Studies; first author Dr. Mark Schoeberl, chief scientist at the Virginia-based Science and Technology Corporation in Hamburg, Virginia; and multiple scientists from the National Aeronautics and Space Administration (NASA).

Their methodology involved analyzing NASA and National Oceanic and Atmospheric Administration (NOAA) satellite data observations of aerosols and water vapor, among other variables, 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 the slight cooling effect.

"Our paper pours cold water on the explanation that the eruption caused the extreme warmth of 2023 and 2024," Dessler explained. "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 Nino."

Implications And Future Research

According to Dessler, this research has important implications for both scientists and the general public. By dismissing the volcanic eruption as a major factor in the recent warming, the team's study reinforces his point that human-induced greenhouse gas emissions are the primary driver of climate change. This focus is particularly relevant, given the ongoing debate and misinformation about the causes of global warming.

Moreover, Schoeberl says the study underscores 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," Schoeberl added. "However, we need to be cautious about a potential 'stratospheric data desert,' as some of the most critical instruments are not being replaced."

The Challenging Path Ahead

While this paper answers several important questions, Dessler acknowledges that it simultaneously 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 by such a violent eruption and the minimal impact the eruption had on the 2023 ozone hole. The 2023 ozone hole refers to a significant thinning of the ozone layer over Antarctica, which allows more harmful UV radiation to reach the Earth's surface. Additionally, the persistence of water vapor in the stratosphere beyond what was predicted by models suggests that there is still much to learn about stratospheric circulation processes.

Read more at Science Daily

Climate impacts are increasing; textbooks aren't keeping pace

A new study from North Carolina State University finds that biology textbooks have done a poor job of incorporating material related to climate change. For example, the study found that most textbooks published in the 2010s included less information about climate change than they did in the previous decade -- despite significant advances in our understanding of how climate change is influencing ecosystems and the environment.

"In short, we found biology textbooks are failing to share adequate information about climate change, which is a generation-defining topic in the life sciences," says Jennifer Landin, corresponding author of the study and an associate professor of biological sciences at NC State. "These books are the baseline texts for helping students understand the science of life on Earth, yet they are providing very little information about a phenomenon that is having a profound impact on habitats, ecosystems, agriculture -- almost every aspect of life on Earth."

For the study, researchers analyzed coverage of climate change in 57 college biology textbooks published between 1970 and 2019. The researchers found that climate coverage has varied substantially over those five decades.

Prior to 1990, textbooks had a median of fewer than 10 sentences addressing climate change. In the 1990s, the median length of climate content was 30 sentences. The median length of climate content rose to 52 sentences in the 2000s, which is not surprising given the amount of emerging research into climate change and its impacts. However, the researchers found that the amount of climate coverage in textbooks actually declined in the 2010s -- dropping to a median of 45 sentences.

In addition to length, the nature of the content has also changed substantially over time. For example, sentences dedicated to actionable solutions to climate change peaked in the 1990s at more than 15% of the climate content. However, in more recent decades, actionable solutions make up only about 3% of the climate content.

"One of the most troubling findings was that textbooks are devoting substantially less space to addressing climate solutions now than they did in the 1990s -- even as they focus more on the effects of climate change," Landin says. "That suggests to students that nothing can be done, which is both wildly misleading and contributes to a sense of fatalism regarding climate change."

In addition, the position of climate change sections keeps moving further back in the books, from the last 15% of the overall text in the 1970s to the last 2.5% of the text in the 2010s.

"This is important because most instructors present textbook content in order, which means topics at the end of the book are often skipped," Landin says.

"However, it's not all bad news," Landin adds. "Textbooks in the 2000s and 2010s began including a wider variety of climate-relevant information, such as how climate is affecting species distributions, which can help students understand the various impacts of climate change.

Read more at Science Daily