The Hunga Tonga Global Warming Con At The Con

h/t Doug Brodie

The Conversation has today posted this article:

Hunga Tonga-Hunga Ha’apai (Hunga Tonga for short) erupted on January 15 2022 in the Pacific Kingdom of Tonga. It created a tsunami which triggered warnings across the entire Pacific basin, and sent sound waves around the globe multiple times.

A new study published in the Journal of Climate explores the climate impacts of this eruption.

Our findings show the volcano can explain last year’s extraordinarily large ozone hole, as well as the much wetter than expected summer of 2024 [Eh? Summer 2024 hasn’t begun yet!]

The eruption could have lingering effects on our winter weather for years to come.

Sounds vaguely promising (allowing for typos) until you read this:

In terms of global mean temperatures, which are a measure of how much climate change we are experiencing, the impact of Hunga Tonga is very small, only about 0.015 degrees Celsius. (This was independently confirmed by another study.) This means that the incredibly high temperatures we have measured for about a year now cannot be attributed to the Hunga Tonga eruption.

The author (one of the co-authors of the new study) goes on to say:

But there are some surprising, lasting impacts in some regions of the planet.

For the northern half of Australia, our model predicts colder and wetter than usual winters up to about 2029. For North America, it predicts warmer than usual winters, while for Scandinavia, it again predicts colder than usual winters.

The volcano seems to change the way some waves travel through the atmosphere. And atmospheric waves are responsible for highs and lows, which directly influence our weather.

It is important here to clarify that this is only one study, and one particular way of investigating what impact the Hunga Tonga eruption might have on our weather and climate. Like any other climate model, ours is not perfect.

We also didn’t include any other effects, such as the El Niño–La Niña cycle. But we hope that our study will stir scientific interest to try and understand what such a large amount of water vapour in the stratosphere might mean for our climate.

The whole article is propaganda and an elaborate con. For a start, the ‘new’ study is not new, it’s just a republished copy of an earlier study published in December 2023. The abstracts are identical, as are the authors:

The amount of water vapor injected into the stratosphere after the eruption of Hunga Tonga-Hunga Ha’apai (HTHH) was unprecedented, and it is therefore unclear what it might mean for surface climate. We use chemistry climate model simulations to assess the long-term surface impacts of stratospheric water vapor (SWV) anomalies similar to those caused by HTHH, but neglect the relatively minor aerosol loading from the eruption. The simulations show that the SWV anomalies lead to strong and persistent warming of Northern Hemisphere landmasses in boreal winter, and austral winter cooling over Australia, years after eruption, demonstrating that large SWV forcing can have surface impacts on a decadal timescale. We also emphasize that the surface response to SWV anomalies is more complex than simple warming due to greenhouse forcing and is influenced by factors such as regional circulation patterns and cloud feedbacks. Further research is needed to fully understand the multi-year effects of SWV anomalies and their relationship with climate phenomena like El Nino Southern Oscillation.

Here’s what the original publication states (because the ‘new’ version is not freely accessible):

Earlier studies have estimated the surface temperature impact of SWV anomalies using various scenarios (Solomon et al. 2010; Maycock et al. 2013; Huang et al. 2016, 2020; Li and Newman 2020). Most studies have found only small effects on global temperatures, including Jenkins et al. (2023) who estimated the global mean surface temperature effect of the HTHH SWV anomaly to be 0.035◦C. Our results align closely with those estimates with a global mean averaged near-surface temperature anomaly (2-meter temperature) of 0.015±0.031◦C averaged over years 3-7. However, we have fully consistent WACCM simulations which include radiation, dynamics, and chemistry, and we can therefore perform a detailed analysis of regional surface impacts. Averaged over those five years, there are substantial surface temperature anomalies over the Northern Hemisphere during winter and spring, reaching above 1.5°C over large areas of North America in DJF and close to 1.5°C over central Eurasia in MAM (Fig. 7a,b). There is also a cold anomaly over Scandinavia in DJF, and the Arctic is anomalously warm over most of the year, but most importantly during SON (Fig. 7a-d).

So, the authors find very large positive (and negative) seasonal temperature anomalies due not only to radiative forcing but also to changes in global circulation - which is something I have been pointing out for some time now. All the studies computing only the direct radiative forcing associated with the stratospheric water vapour neglect to account for significant changes in circulation patterns, resulting in warm winters and extreme weather events across the globe. The climate alarmist brigade want it both ways though: whilst simultaneously claiming that Hunga Tonga was not responsible for the 2023/24 warming spike (a very dubious assumption), they tell us that melting Arctic ice, heat waves and even cold spells etc. are due to the recent ‘sudden acceleration’ (“uncharted territory”) in global warming, which must be due to CO2, because it wasn’t Hunga Tonga! This ‘new’ study at least points to the fact that Hunga Tonga may be influencing weather across the globe. But it’s the claim that HTHH was not responsible for the extraordinarily rapid warming in 2023/24 which I find extremely suspect. How can Martin Jucker, the author of the Con article and co-author of the ‘new’ study make that bold claim when his own study found only a “global mean averaged near-surface temperature anomaly (2-meter temperature) of 0.015±0.031◦C averaged over years 3-7”. Jucker et al calculated the mean global surface temperature anomaly expected from the eruption, using a climate model, over a period of five years from 2025-29. This tells us nothing about the response of the climate in 2023!

Furthermore, Jucker’s claim that his 0.015C effect of HTHH on global temperature is independently confirmed by another study is not true. I covered that other study, by Myles Allen et al, here:

What it says is:

On 15 January 2022, the Hunga Tonga–Hunga Ha’apai (HTHH) eruption injected 146 MtH₂O and 0.42 MtSO₂ into the stratosphere. This large water vapour perturbation means that HTHH will probably increase the net radiative forcing, unusual for a large volcanic eruption, increasing the chance of the global surface temperature anomaly temporarily exceeding 1.5 °C over the coming decade. Here we estimate the radiative response to the HTHH eruption and derive the increased risk that the global mean surface temperature anomaly shortly exceeds 1.5 °C following the eruption. We show that HTHH has a tangible impact of the chance of imminent 1.5 °C exceedance (increasing the chance of at least one of the next 5 years exceeding 1.5 °C by 7%), but the level of climate policy ambition, particularly the mitigation of short-lived climate pollutants, dominates the 1.5 °C exceedance outlook over decadal timescales.

The pre-Hunga Tonga global mean surface temperature anomaly was approximately 1.2C. You don’t have to be a genius to work out that 1.5-1.2=0.3C. Allen et al are saying that some time in the 5 years following the eruption of Hunga Tonga, because of the stratospheric water vapour created by Hunga Tonga, global mean surface temperature may increase temporarily by 0.3C, taking us to the ever so scary ‘catastrophic’ 1.5C global warming limit. It looks like that has already happened. But note, 0.3C is not 0.015C! So where’s Jucker’s ‘independent confirmation’ of his claimed miniscule effect upon overall global warming of Hunga Tonga? Not where he says it is. But then again, his claimed miniscule effect is not quite what he says it is, being in fact a five year average calculated from 2025 onwards.