Confusion Erupts over the Hunga Volcano’s Net Climate Cooling Effect 

Atmospheric scientists call for deeper
analyses of climate complexities, as
predictions fail, and warn of the potentially
unforeseen consequences of geoengineering

by Dr. Sarah Buckland-Reynolds 

In an explosive admission, atmospheric scientists concede that climate predictions failed for the 2022 eruption of the underwater Hunga Tonga volcano. 

In a recent article published in Nature Communications: Earth and Environment, atmospheric scientists explained that the 2022 eruption caused massive “unprecedented” outbursts of water vapor – a greenhouse gas, that led to several researchers in the months following the eruption publishing predictions of such significant warming that was thought to result in “potentially push[ing] temperatures beyond the 1.5 °C threshold of the Paris Climate Accord”. Bolstering this hypothesis, the authors noted that there was only “limited sulfur dioxide”, which was thought to reduce the normal counteractive cooling effect of eruptions. 

Note: Although a net cooling effect is usually the expected outcome of land-based volcanic eruptions due to the impact of sulfur-dioxide and other aerosols, the effect of submarine volcanoes is often thought to be more complex. Hunga, being mostly submarine, emitted large quantities of greenhouse gases such as water vapor, leading to the assumption of intense warming.

Actual temperature change estimates published three years in its aftermath, however, show that this hypothesis failed – not only to meet the expected 1.5 °C of warming – but had the reverse impact of cooling the Southern Hemisphere instead of warming it.

What did these scientists miss? 

A False Alarm or Shifting Foundations? 

Just as with biological systems and other arms of science, the climate system is one of immense complexity with multiple feedback mechanisms through coupled interactions among land, air and the ocean that may amplify or suppress counteracting effects. Observations in the short term may accrue and shift to opposing effects when longer-term data are analyzed. Adding to complexity, extraterrestrial factors such as sunspot activity, and even lunar changes influence climate patterns on earth. This complexity, operating at different scales, leads to significant variations in actual weather and climate outcomes experienced at local, regional and global levels. Even differences in particle sizes of emissions of the same chemicals may lead to differing climate impacts!  

This complex design is what makes temperature balance, and the earth remain habitable for millennia. However, incomplete knowledge of climate drivers, questionable assumptions (including uniformitarian, long-age theories), or faulty mathematical derivations of the precise physical relations involved in climate may lead to significant overestimations or underestimations in projections. In the case of the Hunga eruption, new insights were revealed that the greenhouse gas of water vapor interacted with ozone and the sulfur dioxide “in ways that did not amplify warming.” 

Various authors have pointed out the level of uncertainty that climate scientists must grapple with in making accurate predictions. To many authors’ credit, a close examination of technical climate publications does often reveal explicit mentions of the numerous limitations and assumptions involved in their models. 

If this is so, why does alarmist language filter into mainstream media choosing to report projections in no uncertain terms while virtually neglecting quantifications of uncertainty into simplified models? 

One may ask: To what extent are non-scientific factors such as geopolitics and economic incentives responsible for muddling the waters in some circles of the discipline? 

Revealing a Rupture 

The Hunga volcano eruption in Tonga Jan 15, 2022 surprised experts. (Earth Observatory satellite, NASA)

The Hunga eruption’s projected versus actual impact was not only literally groundbreaking but also revealed an important rupture in climate discourse that every sincere climate scientist should beware of: Separating storytelling interpretations from actual observed data. While storytelling may capture hearts and spur action, Hunga only brings one of the latest examples of how just slightly more extended observations point to a less alarmist outcome than the storyline projections publicized from short-term data estimated about climate changes. 

This “short-term warming, longer term cooling” scenario then brings us to the question: What does this mean for projecting present climate data far into the future? Regardless of the side taken on the climate change discourse on the primary drivers of variability, care should be taken to openly admit that there are many unknown variables involved in climate dynamics that vary on seasonal scales to centennial (and possibly millennial) timeframes. Therefore, modeling should always be reported with a clear explanation of the limitations (with the level of uncertainty quantified or otherwise described). 

While levels of uncertainty are routinely reported in the technical literature citing projections, this is much less publicized in mainstream reports. The assumptions built into modeled data should be transparently disclosed in public reports. Meanwhile, climate scientists may continue to advance the field in useful ways by using observational science to test climate models through hindcasting (testing model simulations of past weather/climate) or comparing simulated and actual measurements over time to help to reduce error margins and refine our understanding of climate dynamics. 

Another ‘Aftershock’ for Geoengineering 

Compounding upon the failed temperature predictions, the Hunga eruption study has further implications for ongoing efforts to geoengineer climate change reversals using aerosols. In a commentary published by UCLA, the institution of some of the authors, it was pointed out that “geoengineering could have multiple consequences”. 

Commenting on the implications of his study, the lead author admitted the following:  

If we plan to use approaches that involve releasing sulfate aerosols into the stratosphere to reflect sunlight, we have to consider how other factors — such as water vapor and atmospheric mixing — could change the outcome, ….The overall impact of such measures depends on understanding the complex interactions among atmospheric components that affect the formation and properties of stratospheric sulfate aerosols…. It is crucial to thoroughly understand a given atmospheric system to determine whether a proposed geoengineering approach will ultimately lead to cooling or warming.

If data from one eruption on such a relatively small scale after three years could highlight such nuanced complexities of climate, what would the potential magnitude of the global aftershock be when the decades-long, global-scale efforts in geoengineering are completed? Perhaps Hunga is a wake-up call for more climate scientists to question assumptions and not experiment until long-term monitoring and evaluation studies potentially reveal unintended consequences for the globe. 

A Hunga for Truth 

If there is any lesson from this case, the Hunga Tonga–Hunga Haʻapai volcanic eruption evokes a voracity for veracity – a dire desire for openness and honesty in the fascinating field of climate science, as short-term observations and assumed roles of elements within the climate system may change significantly even over relatively short period of time. While harnessing knowledge from environmental physics to uncover patterns and predictive analyses is commendable, modeled simulations should be treated as such – simplifications of reality, based on simplifications of observational data, but distinct from observational science. 

While we are encouraged to be good stewards while having dominion, let us remember to have a Hunga for truth as we continue discovering the multifaceted dynamics of our wonderfully complex, created world. 

See also: Volcanoes Cause Global Warming – CEH 

Dr. Sarah Buckland-Reynolds is a Christian, Jamaican, Environmental Science researcher, and journal associate editor. She holds the degree of Doctor of Philosophy in Geography from the University of the West Indies (UWI), Mona with high commendation, and a postgraduate specialization in Geomatics at the Universidad del Valle, Cali, Colombia. The quality of her research activity in Environmental Science has been recognized by various awards including the 2024 Editor’s Award from the American Meteorological Society for her reviewing service in the Weather, Climate and Society Journal, the 2023 L’Oreal/UNESCO Women in Science Caribbean Award, the 2023 ICETEX International Experts Exchange Award for study in Colombia. and with her PhD research in drought management also being shortlisted in the top 10 globally for the 2023 Allianz Climate Risk Award by Munich Re Insurance, Germany. Motivated by her faith in God and zeal to positively influence society, Dr. Buckland-Reynolds is also the founder and Principal Director of Chosen to G.L.O.W. Ministries, a Jamaican charitable organization which seeks to amplify the Christian voice in the public sphere and equip more youths to know how to defend their faith.