Human Vs Volcano: Who Pollutes More?

Volcanic eruptions release large quantities of greenhouse gases and other aerosols into the atmosphere, which can have a detrimental impact on the Earth's biosphere. However, human activities emit 60 or more times the amount of carbon dioxide released by volcanoes annually. While volcanic eruptions can inject significant amounts of carbon dioxide into the atmosphere, human emissions from burning fossil fuels and other industrial activities continue consistently, year after year. This distinction is important when considering the relative impact of volcanic and human pollution on the environment.

Human activity emits 60 times more carbon dioxide than volcanoes

Human activity emits 60 or more times the amount of carbon dioxide released by volcanoes each year. While volcanic eruptions release large quantities of greenhouse gases, human activities emit far more carbon dioxide on a consistent, long-term basis.

Volcanoes emit carbon dioxide during eruptions and through underground magma. While large, violent eruptions may briefly match the rate of human emissions, they are too infrequent to rival humanity's annual emissions. For instance, the 1980 eruption of Mount St. Helens released around 10 million tons of carbon dioxide in nine hours, an amount that humans now emit in just 2.5 hours. Similarly, the climactic eruption of Mount Pinatubo in 1991 injected a 20-million-ton sulfur dioxide cloud into the stratosphere, causing significant aerosol disturbances. However, such massive eruptions are rare.

According to the U.S. Geological Survey, the world's volcanoes generate about 200 million tons of carbon dioxide annually, while automotive and industrial activities cause approximately 24 billion tons of emissions each year. This means that human activities are responsible for more than 90 times the amount of carbon dioxide emitted by volcanoes. Some individual U.S. states emit more carbon dioxide in a year than all the volcanoes on Earth combined.

Since the Industrial Revolution, human emissions from fossil fuels and cement production have risen to over 35 billion metric tons per year, while volcanoes produce less than 1 billion metric tons. Human activities, including the burning of fossil fuels, deforestation, and cement production, emitted roughly 40 billion metric tons of carbon dioxide in 2015 alone. As a result, human activities have added more than 2,000 billion metric tons of carbon dioxide to the atmosphere since the Industrial Revolution.

While volcanic eruptions can have significant short-term impacts on the climate, such as temporary global cooling due to sulfur dioxide emissions, the consistent and persistent nature of human emissions far outweighs the sporadic nature of volcanic activity in terms of overall pollution and long-term climate impact.

Volcanic eruptions can cause global cooling

Human activities emit 60 or more times the amount of carbon dioxide released by volcanoes annually. While volcanoes emit carbon dioxide during eruptions and through underground magma, human activities such as burning fossil fuels, cement production, deforestation, and other landscape changes are the primary contributors to carbon dioxide emissions.

Despite this, volcanic eruptions can have a significant impact on global climate change. While carbon dioxide released by volcanoes can contribute to global warming, the sulfur dioxide injected into the stratosphere during eruptions can lead to short-term global cooling. The aerosols formed from the conversion of sulfur dioxide to sulfuric acid reflect radiation from the sun back into space, cooling the Earth's lower atmosphere.

The climactic eruption of Mount Pinatubo in 1991, for example, injected a 20-million-ton sulfur dioxide cloud into the stratosphere, causing the largest aerosol disturbance of the twentieth century. This eruption cooled the surface of the Earth globally by about 0.5 degrees Celsius a year later. Similarly, the 1783-1784 Laki fissure eruption in Iceland released a significant amount of sulfur dioxide, resulting in regional cooling in Europe and North America.

A 2023 study published in the Proceedings of the National Academy of Sciences (PNAS) found that massive volcanic eruptions caused historical global cooling. By analyzing sulfur isotopes in ice cores from Greenland and Antarctica, researchers linked unusually cold decades, such as the 540s, 1450s, and 1600s, to large volcanic eruptions. The study also revealed that the sensitivity of summer temperatures to high-latitude eruptions is influenced by climate feedbacks, including sea ice extent and ocean heat content.

While volcanic eruptions can cause global cooling, the overall impact on climate change is complex. The cooling effects of small and medium-sized eruptions may decrease by up to 75% as global warming continues to accelerate. On the other hand, large-magnitude volcanic eruptions will have greater effects as the climate warms, with climate change causing volcanic plumes to rise higher and spread faster, amplifying the cooling effect.

Volcanic gases have detrimental impacts on vegetation and animal life

Volcanic smog, or "vog", is produced from sulfur dioxide (SO2) gas and is a hazard in Hawaii. SO2 can also cause global cooling and, along with hydrogen halides, contributes to acid rain. Acid rain can corrode metal infrastructure and coat grass, streams, and lakes with excess fluorine, which is lethal to animals that eat it. Fluorine gas can also condense on ash particles, which, when ingested by animals, can cause fluorosis, an affliction that destroys bones and eventually kills animals.

High concentrations of CO2 in the soil can damage or destroy vegetation, as can be seen in several areas on Mammoth Mountain. Volcanic ash particles can also be coated with hydrogen halides, which are toxic to humans and animals. When molten lava flows into the ocean, it creates large, acidic steam plumes containing hydrogen chloride and hydrogen fluoride gas, which may affect water supplies close to the eruption.

Volcanic activity is uncontrollable and unpredictable

Volcanic activity is unpredictable and uncontrollable. Volcanologists describe volcanoes as active, dormant, or extinct based on how recently they erupted and the likelihood of them erupting again. An active volcano is currently erupting or has erupted in recorded history. A dormant volcano is not currently erupting but is likely to in the future. An extinct volcano is one that is not likely to erupt again. However, the boundaries between these classifications are not always clear-cut. For example, a volcano that has not erupted for a thousand years may still be considered active.

There are about 1,350 potentially active volcanoes worldwide, not including the continuous belts of volcanoes on the ocean floor. The United States alone has 169 active volcanoes, more than half of which could erupt explosively and pose a danger to commercial air traffic. While volcanic eruptions are relatively rare, their impact can be devastating. Volcanic hazards include lava flows, pyroclastic flows, lahars, jökulhlaups, landslides, and debris avalanches. These can affect areas in the immediate vicinity of the volcano as well as locations thousands of kilometres away. Volcanic gases, such as sulfur dioxide, can also cause global cooling, while volcanic carbon dioxide emissions contribute to global warming.

The unpredictability of volcanic eruptions lies in the complex and varied nature of volcanic activity. Volcanism is influenced by a multitude of factors, including plate tectonics, magma movement, gas emissions, and effusive lava flows. While scientists have made significant strides in understanding and monitoring volcanic activity, the exact timing and magnitude of eruptions remain difficult to predict with absolute certainty. This is due to the dynamic and often hidden nature of the processes occurring beneath the Earth's surface.

Volcanic eruptions can be triggered by a range of factors, some of which are still not fully understood by scientists. One key factor is the movement of tectonic plates, which can cause volcanic activity when they interact with hotspots in the mantle. The build-up and release of pressure within the Earth's crust and the movement of magma can also lead to eruptions. Additionally, the presence of gas and the composition of the magma can influence the likelihood and intensity of an eruption.

While volcanic eruptions are natural and unpredictable events, human activities can also play a role in triggering or exacerbating them. For example, certain industrial activities, such as mining or fracking, can potentially induce seismic activity and increase the likelihood of volcanic eruptions. However, the direct causal link between human activities and volcanic eruptions is still a subject of ongoing scientific investigation.

Human emissions are more consistent and long-lasting

Human emissions are far more consistent and long-lasting than volcanic activity. While volcanoes can release huge amounts of carbon dioxide and other gases in a single eruption, these events are rare and fleeting. In contrast, human activities emit carbon dioxide continuously and at a much higher annual rate. For instance, according to the U.S. Geological Survey, human activities produce about 24 billion tons of CO2 emissions each year, whereas volcanoes generate around 200 million tons of carbon dioxide annually. This means that human emissions are more than 60 times greater than volcanic emissions.

The consistency of human emissions is evident in the steady rise of atmospheric CO2 levels year after year, regardless of whether there have been major volcanic eruptions during that period. If volcanic eruptions were the primary driver of increasing carbon dioxide concentrations, we would expect to see spikes in the data corresponding to each eruption. Instead, the data shows a smooth and regular upward trend, reflecting the constant and cumulative impact of human activities.

The burning of fossil fuels, industrial processes, and deforestation are all human activities that contribute to the consistent release of greenhouse gases into the atmosphere. These emissions have already led to significant warming of the planet, with far-reaching consequences for ecosystems, weather patterns, and human societies. Unlike volcanic eruptions, which can cause temporary periods of global cooling due to the injection of sulphur dioxide and other particles into the stratosphere, human-induced warming is persistent and cumulative.

While it is true that volcanic eruptions can have a significant impact on the environment and human activities, their influence is typically short-lived and localized. Volcanic gases, ash, and aerosols can affect air quality, damage vegetation, and disrupt local ecosystems, but these effects are often contained within specific regions and dissipate over time. In contrast, human emissions contribute to global climate change, which has pervasive and long-lasting effects on a planetary scale.

In summary, while volcanoes can release large amounts of pollutants during eruptions, human emissions are far more consistent and long-lasting. The continuous nature of human activities that produce greenhouse gases, combined with their significantly higher annual emissions, makes human-induced pollution a far more pressing concern for the planet's health and future.

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