A Volcano Erupting, And What It Means For Weather and Climate

Of the dozens of factors that can affect local and global climate, as well as the longer-ranging effects of climate change, natural disasters are the least predictable. While it’s true that climate change can cause more intense storms and other types of disasters by virtue of a warming planet, it’s also true that natural disasters such as volcano eruptions can also have an impact on climate change.

What Are Volcanoes?

Volcanoes are mountain formations that drill down through the crust of the earth down to the magma layer underneath. The molten rock that makes up the majority of the core of the planet becomes lava when it is exposed to the atmosphere, and volcanoes provide an opening for this type of internal planet venting to occur. 

Throughout human history, disasters created by volcanoes have been some of the most popularized, as well as some of the most destructive. One of the most well-known volcano disasters is seen in the ruins of Pompeii, an Italian city that was buried under layers of ash and pumice after the eruption of Mt. Vesuvius in 79 C.E.

The Most Famous American Eruption

In America, the largest and arguably most famous volcanic eruption of the modern era is the eruption of Mt. St. Helen’s in Washington State. The eruption had a volcanic explosivity index of 5, and was the first eruption to occur in the contiguous United States since 1915. 

The eruption of Mt. St. Helens had a significant impact on the residents of Washington state, beyond the initial effects of the eruption. Metric tons of ash were released into the air as a result of the volcanic activity, and the poor visibility and pollution of the ash created issues for Washington residents for weeks after the eruption finally ceased. 

Volcanoes as the Cause of Extinction

This is an example of a phenomenon that is a well-known fact in geological circles. Volcanoes and their eruptions can have a significant impact on climate and the planet, though the scale of the eruption is what determines whether the effects are local or global.

Volcanoes have even been attributed as the causal factor behind multiple mass extinction events in earth’s history. Four of the five recognized mass extinction events have occurred contemporaneously with a type of volcanic outpouring called a flood basalt, which flood vast areas with lava in a very short period of time.

Slow Burn to Destruction

The volcanic eruptions that cause these devastating extinctions are not the massive eruptions that most of us think of when considering volcanic activity. Rather than a single mass explosion of molten rock and ash, these are volcanic erupts that leak molten rock and gasses over a period of hundreds of thousands of years, a mere geological second. 

When these massive amounts of lava come into contact with other rocks and materials, the real damage to the earth occurs. Chemical reactions between molten lava and other types of rock and soil create massive releases of different types of gasses, all of which have an ultimately devastating effect on the Earth’s atmosphere.

The Effects of Different Greenhouse Gasses

The effects of different types of gasses are variable, as well. Massive releases of sulfur dioxide lead to short-term cooling (on a scale of decades, rather than centuries), while carbon dioxide and methane cause long-term global warming (on a scale of hundreds of thousands of years). 

These significant climate changes have been pointed to as the reason behind many mass extinctions. Sensitive species are the first to go when the weather changes, triggering an economic chain reaction that can lead to skyrocketing extinction rates, like those events seen in the geologic record.

Current Volcanic Activity

In the short term, massive eruptions of volcanoes can cause similar effects to the planet, though nothing on the scale of planetary mass extinction events. Currently in Indonesia, Mount Ruang is undergoing a significant period of volcanic activity, which has led scientists to consider the effects that the explosions might have on the atmosphere and weather. 

In multiple explosions that were recorded last week, Ruang sent up volcanic gasses into the air that were flung so high that they reached the atmosphere’s second layer, tens of thousands of feet above the ground.

In Indonesia, a Disaster Ongoing

The eruptions ejected a massive ash plume, and sent some gasses more than 65,000 feet in the air, according to satellite estimates. This is about 25,000 feet higher than a commercial airplane will typically fly.

The danger posed by the volcanic activity has caused evacuations to occur in nearby towns, with people seeking cover to protect themselves from the hot ash and the lava that the mountain is spewing. On a grander scale, though, scientists have been considering the effect that the eruption will have on climate and weather.

Short Term Effects of Eruptions

As explained, it is possible for massive eruptions of volcanoes to have an impact on the weather in the short term, but scientists have determined that the effect of the Ruang volcanic explosion will likely be fairly minimal. 

In the short term, the ash released by the volcano – which is made up of a mixture of crushed-up solids, including rocks, minerals, and glass – generates a lot of static electricity within the ash plumes. This results in intense displays of lighting, according to Greg Huey, the chair of Georgia Tech’s School of Earth and Atmospheric Sciences.

Ash in the Atmosphere

“The ash itself is short-lived in the atmosphere because it’s heavy, it’s big, and it tends to settle out quickly,” Huey said in an interview. He went on to explain that it’s not necessarily the ash that is a concern for climate scientists, it’s the gasses that are released at the same time, and are able to reach much higher in the atmosphere.

Dense ash near the surface creates hazardous air quality and causes a temporary cooling effect as it blocks out warming sunlight, but these effects are generally short-lived. Once the active eruption stops, the ash starts to settle, though it can easily be lifted back into the air by wind currents.

Gasses Climbing Into the Stratosphere

Some of the gasses that were released by Ruang’s explosion climbed so high that they reached the stratosphere, which is the second layer of the Earth’s atmosphere. It’s located just above the troposphere, which is where all life and visible weather occur.

The stratosphere is a dry place, and typically only the gasses with a very long lifespan are able to filter up into it. According to Huey, a volcanic eruption is the only natural way for short-lived gasses like sulfur dioxide and water vapor to make their way up into the stratosphere.

A Cooling Effect

Once these short-term gasses are in the stratosphere, though, they can have a significant effect on global climate. Sulfur dioxide combines with water vapor to form sulfuric acid aerosols, which create a layer of hazy droplets. These droplets spread far from their initial point of entry and can remain in the atmosphere for up to three years, reflecting sunlight back into space and causing global temperatures to cool. 

This cooling effect is generally short-term, but it can last for longer periods if larger amounts of gas are released into the atmosphere. In 1991, Mount Pinatubo erupted in the Philippines, and produced the largest sulfur dioxide cloud on record. More than 17 million tons of sulfur dioxide were released into the atmosphere, resulting in a global temperature drop of 0.5 degrees Celsius, which lasted for about a year. 

A Miniscule Eruption, in the Grand Scheme

Compared to that massive explosion, the current Ruang volcanic activity is miniscule. Climate scientists estimate that Ruang has released about 300,000 tons of sulfur dioxide so far, though it’s unclear how much of the gas has made its way up into the stratosphere.

This is not an insignificant amount of sulfur dioxide, by any stretch of the imagination, but it falls far short of the most extreme case, according to Huey. 

Global Action Required

A larger volcanic eruption on the scale of 1991’s Pinatubo’s eruption would certainly work towards cooling the planet for a few years, but it wouldn’t have enough of an impact to erase Earth’s current climate woes caused by human activity and pollution. 

Significant global action will be required on the part of governments all around the world in order to mitigate the ongoing effects of global climate change, though it’s a fact that some damage has already irrevocably been done. While a massive volcanic eruption might mitigate some of the effects in the short term, the catastrophic effects of such a disaster wouldn’t be worth the benefits.