The Campi Flegrei supervolcano, located near the city of Naples in Italy, last erupted almost 500 years ago. However, it is currently geologically active with that activity becoming more intense and frequent. There are signs that this supervolcano could erupt in the future. According to Associate Professor Peter LaFemina, a Geoscientist at the Pennsylvania State University, the Campi Flegrei supervolcano can be best described as a restless caldera, which “is in an almost constant state of geological unrest.”
The Campi Flegrei supervolcano, which means “burning fields”, is also known as Phlegrean Fields. It is a large (roughly 8 miles wide) bowl-shaped depression located under the western outskirts of Naples. The Fields extends under the Gulf of Pozzuoli in the Tyrrhenian Sea west of Italy. Many volcanic centers, including cinder cones, tuff rings, and calderas, are found in the Phlegrean Fields and have been active during the past 30,000-40,000 years. The volcanic field has been the site of some extremely violent eruptions in prerecorded history, though much of the volcanic activity over the past 3000 years has been minor.
By definition, a supervolcano is a volcano that is capable of ejecting a massive amount of material. According to the defined threshold, 1,000 billion kilograms of material are ejected from an eruption. There are 34 volcanoes worldwide that have had eruptions of at least this size, although none of them in modern times.
This volcanic region is located about 100 miles northwest of Pompei, across the Gulf of Naples. Pompei is famously known as the location of one of the most famous and deadly volcanic eruptions in recorded history, Mt. Vesuvius. The entire region was shaped 39,000 years ago as part of the largest eruption Europe has seen in the past 200,000 years.
A study released late in 2016 in the journal of Nature Communications, led by Italian and French scientists from the National Institute of Geophysics and Volcanology in Bologna, tells of the warning signs of a volcanic eruption. The most alarming observation is the uplifting of the Fields which is a sign of gases accelerating towards the surface. The report also points out the threat to the roughly 500,000 people living in the Naples region. The study “highlights the urgency of obtaining a better understanding of Campi Flegrei’s behavior,” said Giovanni Chiodini, a researcher who was part of the study.
In general, volcanic eruptions can alter both the weather and the climate of the region where the volcano is found. Dr. LaFemina, explained, “In the short term after a volcanic eruption, the ash and dust being erupted into the atmosphere generally has a cooling effect as solar radiation that normally would hit the ground and warm the air is reflected back into space by the particles while other amounts of solar energy are absorbed by these particles and never reach the Earth’s surface”.
Scientists would call the “reflection” of solar radiation “albedo.” Around a volcano eruption, the albedo of the atmosphere near the volcano increases due to the particles which in turn causes the cooling. Albedo, which can be thought of as the “whiteness” of an object, is measured on a scale with 1 being the greatest amount and 0 the least. Objects such as newly fallen snow have a very high albedo of 0.8 or 0.9 meaning that almost all of the sunlight that hits it is reflected back into space and almost no energy from the sun is absorbed. On the opposite end of the spectrum is dark soil, which absorbs almost all of the sun’s light and reflects almost none. Interestingly enough, the particles may also act as a “blanket” at night, causing warmer temperatures than if the particles were not there. In general, dust and ash particles will cool more during the day than they warm the night, causing a net cooling.
In the immediate vicinity of the volcano, lightning can be caused by an eruption. Lightning is likely caused by particles moving past and colliding with each other and creating an electrical charge on these particles. According to Dr. LaFemina, “Volcanic lightning is seen in a variety of different styles of volcanic eruptions. However, the eruptions must be explosive enough in nature to cause the colliding or rubbing of the ash particles.”
“A great example of volcanic lightning”, Dr. LaFemina continues, “was in the 2010 eruption of the Icelandic volcano Eyjafjallajokull. This volcano was also well known as the eruption that brought airline travel over the North Atlantic to a complete standstill due to the amount and elevation of ash particles erupted into the atmosphere.”
Sometimes rain in the vicinity of an eruption can be acidic as sulfur dioxide gas released by the volcano combines with water vapor and causes a sulfuric acid rain to fall. Dr. LaFemina has seen extreme examples of localized destruction of ecosystems and infrastructure by strong acid rain around volcanic systems.
In the long-term, volcanoes degas a lot of carbon dioxide into the atmosphere. Carbon dioxide is known to cause warming in our atmosphere. But Dr. LaFemina added, “Volcanoes have been erupting since the dawn of time. With every eruption, and even in a non-eruptive period, carbon dioxide and other greenhouse gases such as methane, water vapor and sulfur dioxide are released. This is a completely natural process and is a large part of how our atmosphere formed. This phenomena should not be confused with the unnatural release of carbon dioxide and other greenhouse gases by the burning of fossil fuels and other man-made influences. No matter what side of the man-made climate change argument one is on, the process of releasing greenhouse gases by active volcanoes and through the gaseous diffusion through magma should be considered a ‘background signal’ and not part of the debate.”
Other long-term changes to the climate can be observed. The more ash/dust the volcano ejects and the higher these particles are able to get into the atmosphere plays a big role into these climatic changes. Also, how large the particles adds an additional variable into this equation.
If a very strong eruption was able to cause small particles to get very high into the atmosphere, the dust and ash may get stuck in the atmosphere and increase the absorption and albedo of solar energy on a large scale. Here, depending on the location of the volcano, the ash/dust particles may be carried by high level winds such as the jet stream across the globe or at least a hemisphere. The smaller the particles are, the less likely they will fall on their own due to gravity and will remain high in the atmosphere.
Small enough particles can find their way high enough into the atmosphere where they may remain for an extended period of time, sometimes weeks and even months. This is particularly true if these particles are pushed into the stratosphere, which is the layer of the atmosphere above the layer which we live, the troposphere. Instead of falling temperatures with height as in found in the troposphere, the stratosphere is reversed. This is a very stable setup and once the particles get into the stratosphere, they will persist there for months or years. Sunlight that would normally reach the Earth and warm the planet is reflected back into space due to the increased albedo or the sunlight is absorbed. Like mentioned above, this would cause a net cooling but now on a global or hemispheric level as compared to only local effects.
Once these particles do get into the stratosphere, the result can be a volcanic winter. A cooling of at least 0.5 degrees Fahrenheit for several months to 2 or perhaps 3 years is the definition of a volcanic winter. There have been several times in recorded history where volcanic winters have been observed.
An extreme type of volcanic winter that has been studied and theorized upon is a “nuclear winter”. This term is best described as an extreme cooling event that would dramatically alter the climate of the Earth as a whole by causing a drop in global temperatures. In the time of the Cold War between the former USSR and the United States, nuclear war was a huge concern. And not only for social and economic reasons. Meteorologists and climatologists tried to theorize of how a nuclear war would affect the climate. Dr. LaFemma added, “The best example that meteorologists and climatologists could compare to the amount of particulates that a nuclear war would throw into the atmosphere would be the eruption of a supervolcano. The full scale eruption of Campi Flegrei or the Yellowstone supervolcano in Wyoming could result in a nuclear winter.”
Two relatively recent volcanic winters are great examples of this net cooling on a hemispheric level. The most recent was Mt. Pinatubo in the Philippines which was the 2nd largest eruption of the 20th century. Occurring on June 15, 1991, this volcano caused enormous amounts of dust and ash particles to be thrown high into the atmosphere This large injection of foreign particles led to a decrease of average temperatures of 0.5–0.6 °C (0.9–1.1 °F) in the northern hemisphere over the next year. Increased levels of dust and ash persisted high in the atmosphere for three years.
Mt. Tambura in the Dutch East Indies, which is present day Indonesia, saw the peak of its extremely violent and long-lasting eruption on April 10, 1815. At that time, it was the largest volcanic eruption in the world since the year 180 AD. Particles continued to stream from this volcano for at least six months with some estimates being much longer, up to three years.
Scientists do not have the specific scientific details of this eruption in the way they do for Mt. Pinatubo. However, there is little doubt in the scientific community that what followed in 1816, which became known as “the Year without a Summer” was at least somewhat due to the eruption. The regions of western Europe, eastern Canada and the Northeast saw weather conditions that were almost hard to believe. Some of the most unusual climatic reports were five consecutive late June nights with frost in Cape May, New Jersey; snow falling on June 7th and 8th in Massachusetts and lake and river ice found in July and August as far south as northwestern Pennsylvania.