A violent eruption of Mount Agung could also have ramifications beyond Bali, as it threatens to alter the global climate.

Cancelled flights, missed connections and expiring visas have turned Bali into a nightmare for thousands of tourists scrambling to leave, as a volcano on the Indonesian vacation paradise threatens a major eruption.

Hundreds of flights have been grounded as the main international airport was shuttered, leaving close to 120,000 stranded visitors in need of shelter — or an exit plan.

If Mount Agung erupts, the impact on the island would be disastrous, crumbling its economy that is largely dependent on tourism and agriculture. But the eruption could also have ramifications beyond Bali, as it threatens to alter the global climate.

A Washington Post report says that the eruption could alter the global temperature for months and maybe even years to come.

"In the short term, ash particles would cause regional cooling, as the layer of dust prevents some sunlight from reaching the ground. In the long term, sulphur dioxide would mix with water droplets in the atmosphere, spread across the globe and reflect sunlight for up to three years. Average global temperature could decrease significantly," the report says.

Earth to become cooler?

Volcanic eruptions can violently shake up the immediate proximity of the eruption site but scientists believe that the millions of tons of gases and particles spewed out into the atmosphere can alter the global temperature, as per a report in Vox.

How much variation is brought about in the temperature, however, depends on what’s being erupted and the location of the eruption.

If these conditions are met, the eruption cools the surface/troposphere and warms the stratosphere, the opposite of both patterns associated with CO2 increases. But both are very short-lived (~years). — Chris Colose (@CColose) November 27, 2017

According to a UCAR study on how volcanoes influence climate, "Most of the particles spewed from volcanoes cool the planet by shading incoming solar radiation. The cooling effect can last for months to years depending on the characteristics of the eruption. Volcanoes have also caused global warming over millions of years during times in Earth’s history when extreme amounts of volcanism occurred, releasing greenhouse gases into the atmosphere."

According to the Vox report, while the carbon dioxide emitted during an eruption traps heat, the ash particles and gases like sulfur dioxide, which form compounds that reflect sunlight, are also released that form a temporary shield, thereby cooling the planet.

Global impact

Alan Robock, an environmental scientist at Rutgers University, corroborated this theory while speaking to Mashable.

"The ash doesn't matter. What matters is the chemistry of the stuff that’s being ejected — and how it's ejected," Robock added.

Once high in the sky, sulfur dioxide reacts with water to produce droplets that can linger for a year or more. And when sunlight hits these droplets, energy is reflected back into space, depriving Earth of substantial amounts of sunlight, he said, as per the report.

The UCAR study further states that despite the location of the eruption, the impact can be global: "Even though volcanoes are in specific places on Earth, their effects can be more widely distributed as gases, dust, and ash get into the atmosphere. Because of atmospheric circulation patterns, eruptions in the tropics can have an effect on the climate in both hemispheres while eruptions at mid or high latitudes only have an impact the hemisphere they are within."

The problem is, adds the Washington Post report, we don't know whether Agung is just warming up on its way to a massive explosion, or whether it’s going to simply simmer.

If this eruption turns out to be anything like previous eruptions of this volcano, it is likely that a significant amount of sulfur dioxide will be released into the air.

The 1963 eruption of Mount Agung knocked down global temperatures between 0.1 and 0.2 degrees Celsius for a year. The same could phenomena could occur given the same scale of the eruption.

"This projection, which is based on the historical relationship between volcanic eruptions and temperature, suggests that an Agung eruption would reduce global temperatures between 0.1 to 0.2-degree Celcius in the period from 2018 to 2020, with temperatures mostly recovering back to where they otherwise would be by 2023," climate researcher Zeke Hausfather was quoted by Vox as saying.

With inputs from agencies