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Australia: How do volcanoes affect the weather and what's going on with the Tongan eruption?

Tonga: a new "large eruption" of the submarine volcano was detected

 Tonga: a new © CIRA / NOAA The submarine volcano erupted three days ago. Here, on January 15th. CIRA / NOAA via Reuters The Hunga Tonga-Hunga Ha'apai has awakened again. A new "big eruption" was detected on the volcano close to the Tonga Islands, entered into activity three days ago, and who triggered a tsunami Saturday in the Pacific, announced Monday (on the night from Sunday to Monday In France) a monitoring station based in Australia.

Despite releasing gases high into the atmosphere, estimates suggest no significant global climate impact. (Supplied: Maxar Technologies) © Provided by ABC NEWS Despite releasing gases high into the atmosphere, estimates suggest no significant global climate impact. (Supplied: Maxar Technologies)

How do volcanoes affect the weather and what's going on with the Hunga Tonga Hunga Ha'apai eruption?

Close to an eruption there is a huge impact as the volcano releases moisture, ash, and gases into the atmosphere.

Within the volcanic plume, electrical charges can build to trigger lightning and the aerosols can seed rain.

Volcanoes can even produce "mud rain" if the conditions are right.

When that rain hits the surface it can then do more damage in the form of a lahar, where volcanic ash flows in a deadly mudslide.

Tonga's Hunga Tonga Hunga Ha'apai volcano's impact felt around the world, from the US to Scotland

  Tonga's Hunga Tonga Hunga Ha'apai volcano's impact felt around the world, from the US to Scotland While authorities are still working to fully assess the damage from the eruption of the Hunga Tonga Hunga Ha'apai volcano, it seems many places that felt its effects have been spared widespread damage.When the Hunga Tonga Hunga Ha'apai volcano erupted on Saturday, it caused a plume of ash, steam and gas to rise like a mushroom above the blue Pacific waters.

Then there is a phenomena known as "vog," volcanic fog, when harmful gases linger near the surface.

But it is when the plume gets further up into the atmosphere that it can start having global effects.

Volcanoes can cool the planet

According to Blair Trewin, senior research scientist at the Bureau of Meteorology, the major global-scale effect of volcanoes is that the bigger eruptions can temporarily cool the atmosphere by releasing sulphur dioxide.

It blocks the incoming light from the sun and acts as a kind of global shade.

But to hang around and have long term affects, the sulphur dioxide needs to get up above the troposphere.

If it remains in the troposphere, where our day-to-day weather takes place, it will be quickly rained back down to the surface.

Fears Tonga disaster death toll will rise

  Fears Tonga disaster death toll will rise As Australia prepares to send more aid and supplies to Tonga following the tsunami, there are fears the death toll will rise.As Australia prepares to send more aid to Tonga, authorities have confirmed the first casualty from the natural disaster, British charity worker Angela Glover.

The plume from the Tongan volcano is estimated to have reached approximately 35 kilometres high, well up into the stratosphere.

"The other thing is that volcanoes which tend to have the greatest cooling effects on climates are in the tropics," he said.

Emissions from the tropics have a much better chance of spreading over both hemispheres, rather than being stuck in one.

So two ticks.

But based on initial estimates, it is not looking like the latest Tongan eruption has released enough sulphur dioxide to cause significant cooling.

"The estimates I've seen so far suggest somewhere around 0.1-0.2 megatonnes [million tonnes] of sulphur dioxide has been emitted," Dr Trewin said.

The last volcano which did have a global cooling effect, Mount Pinatubo in 1991, released significantly more sulphur dioxide.

"Mount Pinatubo emitted about 15 to 20 megatonnes, so somewhere in the order of 100 times more than what the Tongan volcano has."

Australian planes and navy ship loaded with supplies for Tonga

  Australian planes and navy ship loaded with supplies for Tonga Australian C130 Hercules planes and the HMAS Adelaide helicopter dock are being loaded with supplies to take to Tonga in the wake of a devastating tsunami.There are three reported deaths, with two locals and a UK national losing their lives in the tsunami that inundated the Tongan capital Nuku'alofa after the undersea Hunga Tonga Hunga Ha'apai volcano erupted on Saturday.

Mr Trewin said there could be local cooling around the volcano where significant ash is being generated.

"But at a global scale, the eruption we've seen so far, we wouldn't expect to have any significant global climatic impacts," he said.

Dr Trewin does not expect any significant effects on Australian weather form the Tongan volcano.

"Not really, apart from attractive sunsets in some places," he said.

Andrew Tupper of Natural Hazards Consulting and a former manager of the Darwin Volcanic Ash Advisory Centre is likewise not predicting weather interruptions in Australia.

According to Dr Tupper, the volcanic cloud is now travelling out over the Indian Ocean, having crossed Australia.

But because it has travelled around 35km up, it is not affecting our weather.

"The normal rain that we get, even in the summer, the maximum height of thunderstorms is around 16 or 17 kilometres in the tropics, and usually a bit lower in the mid-latitudes," he said.

"So they are just not interacting with that volcanic cloud."

Could there still be more to come?

The question remaining is if any more sulphur dioxide could be released in follow-up eruptions.

Tonga says it is facing ‘unprecedented disaster’, many missing

  Tonga says it is facing ‘unprecedented disaster’, many missing In first official statement on Saturday’s volcanic eruption and tsunami, government confirms at least three dead.In its first statement since the undersea volcano Hunga Tonga-Hunga Ha’apai erupted on Saturday, the prime minister’s office late on Tuesday confirmed the deaths of at least three people, including a British woman.

Heather Handley, volcanologist and  adjunct associate professor at Monash University, said it depended on how much of the gas has been lost previously and how much is stored.

Her work on samples from the same volcano in 2009 showed the magma that formed rocks at the surface had travelled quickly and retained a lot of its gas.

"So there is potential that if there are larger scale eruptions it could contribute significant sulphur dioxide into the atmosphere," Dr Handley said.

"But we just don't know at this stage what the next steps for the volcano are.

"It's hard to predict whether that's going to continue to erupt, or produce a big eruption, or just decline in activity now."

World-cooling volcanoes

As mentioned, the last volcano to have a significant impact on the global climate was Mount Pinatubo in the Philippines in 1991.

According to Dr Trewin it was one of three eruptions in the last century which had a major effect on global climate — the others being El Chichón in Mexico in 1982 and Mount Agung in Bali in 1963.

The biggest eruption in recorded human history was Mount Tambora in 1815 in Indonesia.

Its cooling effects led to 1816 being know as the year without a summer.

According to Dr Handley, it affected different areas of the planet in different ways.

Eruption of the volcano in the Tonga Islands: the time is at the eighty food

 Eruption of the volcano in the Tonga Islands: the time is at the eighty food © Handout New Zealand Defense Force / AFP The Tonga Islands are practically cut from the rest of the world since the volcanic explosion of Saturday, January 15, 2022. International aid begins to reach the Tonga Islands one week after the volcanic eruption followed by a devastating tsunami in this Pacific archipelago. The first aircraft and vessels carrying emergency assistance as well as communication devices have arrived on site. A thick layer of volcanic ash now covers the archipelago.

"[Researchers] linked that to things like a more successful polar bear breeding season because of the cool air, but then it affected a lot of crops in the northern hemisphere and led to famine," she said.

"So there were much wider reaching impacts of these larger scale volcanic eruptions that impact the climate."

Preparing for disaster

"One thing which I think's really cool in this context is that there was a major eruption in 1808 which is known about, both from it's climatic impact — from some of the deposits — and also from things like sunsets," Dr Trewin said.

But no one knows where the volcano was.


It is referred to as the "mystery eruption".

"The most prominent theory is that it was an undersea volcano somewhere in the South Pacific and whatever island it was on was destroyed by the eruption, never to be seen again," Dr Trewin said.

So climate-changing eruptions have certainly happened before and will certainly happen again.

For Dr Tupper, the Tongan eruption acts as a reminder that natural disasters often reach beyond one type of hazard or field of science.

"Over the last two years we've been dealing with COVID and some of the other stuff has has taken a back seat," he said.

"But but an eruption like this just reminds us of all the natural hazards in the region and the importance of monitoring them and building better warning systems."

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Eruption of the Volcano to the Tonga Islands: the fear of COVID complicates the routing of help .
© AFP - Sgt Ben Dempster The humanitarian aid routed by the French military aircraft will remain three days outdoors to avoid any contamination. Here, a humanitarian military aircraft from Australia at Fua'amotu International Airport in Tonga, January 22, 2022. For a week, international aid arrives on the Tonga struck by a powerful volcanic eruption and a tsunami.

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