When Mount Etna, in Sicily, spewed a mammoth 12-kilometre-high column of volcanic ash, recently, it re-affirmed nature's own cyclic history.

The volcano's most-devastating flare-up occurred in 1669, when lava ransacked several villages, while plunging Catania, the largest city in the east.

Picture this: a colossal underwater volcano erupted close to the tiny, unpeopled a toll of Hunga Tonga-Hunga Ha'apai, early this year. It had the highest plume that rose to 58km, at its highest point. The previous record was held by the 35-km volcanic plume - Mount Pinatubo's 1991 eruption in the Philippines.

The eruptions were evidenced to be twice the size of El Chichon's massive outburst, in Mexico, which took place in 1982.

What's more, the Pinatubo haze lowered global temperatures, just like the former did, by more than half-a-degree Fahrenheit, for a few years. Besides, the resultant ash spilled to an agricultural catastrophe, animal death and human illness - inflammation (skin and eye), breathing problems, lung damage and suffocation, the most common cause of death from volcano-centric smoke.

There are over 1,500 active volcanoes around the world, out of which approximately 50, or more, erupt every year, while discharging steam, ash, toxic gases and lava. Research also suggests that volcanic eruptions, all over the globe, are 18 per cent more likely during the northern winter months than at any other time of year.

Flashback 2002. The smouldering slopes of Mount Unzen, in Japan, presented a grisly sight.

Scalding rocks and deadly gas erupted from the volcano.

The flare-up was the deadliest in the Land of the Rising Sun, since 1926, when Mount Tokaichi blew up, burying two villages.

Not to be outdone, Mount Fugen spewed lava, with venom, forcing the Japanese to bring in relief to the area on a war-footing.

Mount Pinatubo and Unzen are part of the 30 active volcanoes around the Pacific Rim, labelled as the 'Ring of Fire'. Indonesia has about 170 in the active volcano list, among which approximately 80 have erupted through history.

There was the Barren Island volcanic eruption too, after an extended slumber of over 188 years, in 2005.

Once the eruption made headlines, there was a hectic scramble by Indian scientists to the spot, thanks to a tip-off given by a foreign researcher. As the volcano spewed smoke clouds to a height of about 800 metres, aside from columns of flame 'fountains', the red hot lava formed a slow moving river with its temperature being approximately 900-degree centigrade.

What are the factual effects of volcanic eruptions on global weather? Research contends that the fallout of a major volcanic eruption may linger long after the lava has cooled. A cover of fine dust and sulphuric acid droplets could spread around the Earth and last for ages. There have also been instances when this smoky veil has blocked sunlight, resulting in cooling of the planet's climate.

One example - the eruption of the Indonesian volcano Tambosa, in 1815, was followed by a 'Year without Summer', when parts of New England and Canada were riddled by snowstorms in June and frosts in August.

The plausible connection between volcanic eruptions and climatic changes has been studied for long, yes, and scientists believe that it may not be as cogent as some of the claims made early on. Most computational and observational studies that have analysed global temperature statistics for years on data available from several volcanic eruptions - Krakatau in 1883 to the El Chichon outburst in 1982, among others - suggest that although actual climatic fluctuations have emerged through major eruptions, minor outbursts have had no significant impact on temperature readings.

They emphasise that powerful, dust-spitting explosions, such as at Krakatau, may have caused a drop by a mere half-a-degree, or less, in the average temperature standards in that particular hemisphere.

The interpretation has drawn flak from critics, who contend that a small drop in temperature grades over an entire hemisphere could just as well masquerade important locational changes in climatic conditions.

They also dispute the fact that if volcanic effects were amplified locally by climatic feedback loops, it might not cool the entire planet.

Most sceptics, who have cited the 'Year without a Summer' example, reckon that a small drop in temperature levels in New England, for instance, might delay the melting of snow.

This, in turn, may continue to reflect sunlight away from the surface, adding substance to the cooling effect.

More than that, the cool air would affect the jet stream-i.e., the flow at the margins between the cool northern air and the warm southern air-which takes its 'strength' from differences in temperature and pressure. It could, perhaps, move further south than usual, so as to intensify the cold 'bite' in the area, while a small drop in temperature, they argue, could set off a chain reaction that could lead to a 'summerless' period.

With the heat and dust in the controversy gaining ground, it would only be logical for us to highlight some of positives-ironically, though-of a volcanic 'windfall'. Many volcanic materials have important industrial and chemical uses. For example - the building of roads, polishing stones, metals, making chemicals, among others.

In Italy, Mexico and New Zealand, where volcanic activity is great, the occurrence is used for producing electricity. And in Reykjavik, water 'piped' from volcanic hot water springs is used to heat homes-a natural 'oversized' geyser.

Yet, the sad fact remains - the spectre of a volcanic eruption, or 'a cannon of immense size', as Oliver Goldsmith verbalised, exemplifies not only ruin, like Pompeii, but also nature's undulating fury and human vulnerability.

Nidamboor is a wellness physician, independent researcher and author

A version of this article appears in the print on March 21, 2022, of The Himalayan Times.