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Hunga Tonga burnin' love

12 Jun 2024 | Science Notes

On January 15 2022 the Hunga Tonga-Hunga Ha’apai volcano, which we will shorten mercifully to HTHH or you can just say “Hunga Tonga”, erupted fairly deep under the Pacific Ocean, 150 metres below the surface, in the Southern Hemisphere northeast of Australia. Because it erupted under water, it didn’t send much of the usual volcanic materials like ash and sulfur into the atmosphere but instead caused a massive plume of water vapour to punch all the way up into the stratosphere (from around 20 to 50 km above the surface at the tropics, and perhaps 6 to 50 at the poles) and even into the mesosphere above it, and began circulating around the planet. Since H2O is a powerful greenhouse gas we might suppose that HTHH means warming for the world. But it’s not that simple, since water vapour that far up can cause surface cooling instead of warming. Climate is complicated, as we may have mentioned. Including that water vapour can also change the size of the ozone hole over Antarctic which has climate implications of its own. But now a team of Australian scientists has published a study (free version here) based on climate model simulations presenting an initial estimate of the potential global climate impacts of HTHH. Their conclusion: it caused a lot of Northern Hemispheric warming and it will last a long time. Which if true explains the spike in temperature in 2023 much better than the models can, or the CO2-obsessed theory on which they are based. If, because it’s just one theory in a complicated area and it depends on a whole lot of computer modeling of a sort we regard with skepticism. But it’s an important topic and one well worth pursuing.

The authors admit that trying to figure out how much water vapour got injected into the stratosphere is hampered by a disagreement between estimates from weather balloons (50 Teragrams) and weather satellites (150 Tg), so the authors split the difference and assume 100 Tg. This corresponds to about a 10% boost in the normal water vapour level in the stratosphere. And not just briefly. It will take about 7 years for the H2O to dissipate and for levels to return to normal, and in the meantime the H2O will start doing a lot of things.

For instance, the extra water vapour will support formation of more stratospheric clouds over the South Pole, which will allow the accumulation of more chemical compounds that deplete ozone as the clouds break up in the South Polar Spring. So the authors expect bigger ozone holes in the years ahead, beginning around the 3rd year after the volcanic eruption.

As for temperatures, it will take about two years for the effects to begin kicking in, which if true means the eruption at the start of 2022 cannot have had much impact on the anomalous heat of 2023. But also that we are now at the point where northern hemisphere wintertime temperatures (December January February or DJF, and TS is Time Series) could jump as much as 1.5 deg C in many places:

Other places though will cool, and the global average will end up rising only a small amount. But across North America, Europe, Africa and much of Central Asia, people will experience a wintertime warming jump which could last until 2029. Summertime changes will generally be small.

We will be following the progress of winter temperatures with interest. As noted it’s a modeling study, so we shouldn’t assume the case is closed and the matter is settled, but we can say that the HTHH volcano is already having a potentially significant effect on the climate and some of the warm conditions we experienced over the past year and especially the spring of 2024 might be connected to it. Stay tuned.

3 comments on “Hunga Tonga burnin' love”

  1. Bottom line is volcanoes can and do have a significant effect on climate,both warming and cooling.This has happened many times even in recorded history.Even in the Modern Era.

  2. "As for temperatures, it will take about two years for the effects to begin kicking in"

    Total BS
    The strongest effect would be in the two months after the eruption. There was no observed change to the global average temperature.

    One reason might be that a 10% increase of stratosphere water vapor mean only a 0.1% increase of TOTAL atmospheric water vapor.
    The delayed effect is a fantasyland prediction.

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