Volcanic vs. Man-made Climate Change


01-MtStHelens-eruptionThere are two key questions we need to answer before we can judge how man-made CO2 generation compares to well-observed effects of big volcanoes. “The Little Ice Age” was the first well-studied and documented rapid climate change, and it lasted about 300 years. It decimated Europe, and almost became an extinction event for struggling pioneer New England colonists.

The Tambora volcanic event seems to have been involved.

  • (1) How much of the Little Ice Age might have been caused by human activity, and how much by volcano?
  • (2) If volcanic activity can change the weather, then at what point can we say for sure human activity may serve as a man-made replacement for extraordinary volcanism?

In this article, we’ll compare the outputs of each phenomenon, and look into other components which have been fingered as contributing to climate change. Illustrated and referenced.

The Little Ice Age

I heard “The Little Ice Age” cited during a PBS show on polar melting. The Gulf Stream died, that huge heat engine that brings warm water from the tropics to warm the European climate. Europe nearly died with it. Europe froze, Crops failed, livestock died, people weakened and starved, the Black Death pounced, and millions of human beings perished – from a natural phenomenon.

I remembered that the Little Ice Age has long been associated with a cataclysmic volcano explosion halfway around the world: Mt. Tambora. I wondered, “How do historical volcanic discharges compare with modern man-made injection of greenhouse gases into the atmosphere?”

I also remembered Sen. James Inhofe’s infamous utterance,

“The arrogance of people to think that we, human beings, would be able to change what He is doing in the climate is to me outrageous.”

It became one of those popular memes accepted at face value because it tells us everything many of us want to hear without bother of further thinking or investigation.

I didn’t hear the myth that volcanoes emit “way more” CO2 than mankind until I started researching this article. This myth is BUSTED.

I wondered: might there be a way to disprove this myth directly? How do our enormous discharges of of CO2 and greenhouse gases compare to historic volcanic discharges?

That “Little Ice Age” was a huge climate change, only in the opposite direction of our current concerns about “Global Warming.” We’ll be more interested in the magnitude of change, and the causes of those changes, than their direction.

Some writers speculate that solar orbital cycles, solar activity or even human activities may have contributed to the Little Ice Age (“LIA”). Solar and orbital cycles are well documented. We are not near a solar irradiation peak (Milankovich Cycle) now. The last peak was about 9,000 years ago.

One source even fingered “reforestation” caused by decreased human population [Wikipedia link below]. To be charitable, that hypothesis assumes trees suck up CO2 and replace it with oxygen. That was the situation during the “Jungle Earth” era of the dinosaurs.

Wikipedia’s article Little Ice Age reports show that estimates of the extent of the Little Ice Age do not always agree even to the nearest century. Their article is a good read. Time bracketing would in part depend on the location of the observer. North Americans tend to know more about the effects on European ancestors, but those effects were world-wide.

They were even felt in South America and New Zealand, which, core samples show, were colder too. Not to minimize the effect of a solar minimum or maximum, it is quite logical that several phenomenon might conspire to affect our climate, and a mega-volcano could just be the trigger that tilts the equilibrium suddenly.

The cataclysmic explosion of Mt. Tambora in 1815AD was just such a volcano. “The Tambora blast was ten times more powerful than the Krakatau explosion. Five cubic miles of ash was thrust into the air. Ash fell as far away as New York, and humans bones were carried 4,500 miles across the Indian ocean to Zanzibar.” — Facts and Details Tambora, Krakatua, and Pintatubo.

Tambora injected 48.16 million tons of CO2 into the atmosphere, among other things. If man-made CO2 is injected into the biosphere along the same order of magnitude, could it trigger a sudden climate change at some point?

The Wikipedia article also states: “NASA defines the [LIA] term as a cold period between AD 1550 and 1850 and notes three particularly cold intervals: one beginning about 1650, another about 1770, and the last in 1850, each separated by intervals of slight warming.”

“Human activity” capable of changing the gaseous composition of Earth’s atmosphere largely began with the the Industrial Age, roughly 200 years ago. It’s important we understand why.

Wood vs. Coal

coal-plant-337x220Burning Wood is NOT the same as Burning Coal. Trees cut for fuel would otherwise have died or been consumed by lighting-caused forest fires. Decaying remains then release carbon back into the atmosphere anyway. It was in the biosphere all along. If de-forestation of local patches of primitive community forest cannot be a principal cause of climate change, then neither can re-forestation.

Global deforestation is another matter. But the issue here is the source of the fuel.

There’s a hugely important distinction between the burning or decay of biofuels and the injection of CO2 caused by burning fossil fuels. One we “get” it, the logic is not easily forgotten.

“The Industrial Revolution was the transition to new manufacturing processes in the period from about 1760 to sometime between 1820 and 1840.” [Wikipedia] It was made possible by the very rapid switch from wood [biofuels] to coal [fossil fuel] to power everything about this new Age launched in Europe, and soon after in North America.

The critical distinction dropped by so many is that fossil fuels are “sequestered” — millions of years of decaying carbon-based products were gradually covered or subducted, safely undisturbed, underground.

Coal and other fossil fuels would not again release CO2 and other gaseous and particulate pollution into the atmosphere for millions or billions of years. When we dig it up and burn it, we’re adding to the net CO2 load in the biosphere our extracted fossil byproducts that otherwise would have remained sequestered.

We’ve intentionally examined in some detail what the colossal forces of a valcano can to to the atmosphere, the land, and our climate.

Back to our very simple question:

It is possible for man to out-do volcanism and “be able to change what He is doing in the climate?”

Just how many tons do we introduce?

The graph and text in the Scientific American article “How Much Is Too Much?: Estimating Greenhouse Gas Emissions” gives us a very good idea. Even if one challenges the figures. and there seems to be no reason to do so, we are interested here in orders of magnitude, not small ranges of measurement error.

Their chart shows historic injection since 1950 until 2000, when we started getting serious about controlling CO2 emissions. See the whole chart on their website, linked above.

  • In 1950, the figure was about 2 billion tons annually.
  • In 2000, it was 12 billion tons annually.
  • “Volcanoes emit around 0.3 billion tonnes of CO2 per year” — SkepticalScience
  • Volcanoes release more than 130 million tonnes of CO2 into the atmosphere every year.” — volcanoes.usgs.gov
  • “The fact of the matter is, the sum total of all actively out gassing volcanoes emit CO2 at a rate that is about 1/150th that of anthropogenic emissions.” – Science Blogs

It’s worth noting that some of the worst weather changes caused by volcanoes result from ejection of cubic miles of particulate matter (ejecta, or ask and dust) into the atmosphere, darkening skies and reddening sunsets around the globe.

But particulates settle out, and are precipitated out, in a few years. CO2, being a gas, is merely added to the existing atmospheric carbon load, and it is only removed through natural processes taking thousands of years or more. That’s not to say that particulates can’t have dire shorter-term consequences.

The volcanic/man-made ratios should be expected to vary depending on the base year used, how we estimate volcanic gaseous output, and how we measure factory, power plant and vehicular emissions.

But the numbers agree within one power of ten.

There can be no question we are talking about millions vs. billions. No matter how we quibble, the studies suggest man-made atmospheric injection of long-term greenhouse gases dwarfs volcanic sources by a factor ranging from about 36 to 150.

The Scientific American graph was compiled on or before 2009. If we are still pouring out anywhere near 12 billion tons of CO2 a year (think “China”), then the real factor may be considerably higher than a thousand.


  1. If one Tambora explosion can trigger a frozen Europe and cause a million deaths, what can 12 billion tons of anthropogenic (man-made) CO2 do annually?
  2. Can it explain our current situation and allow us to project our future as things stand now?
  3. Of course it can.

The biggest myth, that natural disaster can cause climate change but puny man cannot possibly alter the Almighty’s climate, is false. This myth is BUSTED.


(1) USGS Volcano Hazards Program

CO2 emission events

Mount St. Helens, 18 May 1980 0.01 Gt
Mount Pinatubo, 15 June 1991 0.05 Gt
Number of Pinatubo-equivalent eruptions equal to annual anthropogenic CO2 700
Number of Mount St. Helens-equivalent eruptions equal to annual anthropogenic CO2 3500

2010 anthropogenic CO2 multiplier (ACM)** 135
1900 ACM 18
1950 ACM 38
Number of days for anthropogenic CO2 to equal a year’s worth of global volcanism: 2.7

* Equal to 2% of the world’s coal-fired electricity-generating capacity.

(2) Consulting Geologist: Krakatoa vs. Tambora

I finally located a direct tonnage estimate for Tambora. Megatons are expressed here as MtCpa.

Year Volcano Source Est. Carbon output during year(s) of eruption
1883AD Krakatoa Shinohara (2008) 26.14 MtCpa
1815AD Tambora Shinohara (2008) 48.16 MtCpa

(3) Wikipedia: Little Ice Age

Volcanic activity

Throughout the Little Ice Age, the world experienced heightened volcanic activity.[71] When a volcano erupts, its ash reaches high into the atmosphere and can spread to cover the whole earth. This ash cloud blocks out some of the incoming solar radiation, leading to worldwide cooling that can last up to two years after an eruption. Also emitted by eruptions is sulfur in the form of sulfur dioxide gas. When this gas reaches the stratosphere, it turns into sulfuric acid particles, which reflect the sun’s rays, further reducing the amount of radiation reaching Earth’s surface. The 1815 eruption of Tambora in Indonesia blanketed the atmosphere with ash; the following year, 1816, came to be known as the Year Without a Summer, when frost and snow were reported in June and July in both New England and Northern Europe. Other volcanoes that erupted during the era and may have contributed to the cooling include Billy Mitchell (ca. 1580), Mount Parker (1641), Long Island (Papua New Guinea) (ca. 1660), Laki (1783) and Huaynaputina (1600).[19]

(4) How Volcanoes Work: Krakatau

The stratospheric cloud of dust also contained large volumes of sulfur dioxide gas emitted from Krakatau. These gas molecules rapidly combined with water vapor to generate sulfuric acid droplets in the high atmosphere. The resulting veil of acidic areosols and volcanic dust provided an atmospheric shield capable of reflected enough sunlight to cause global temperatures to drop by several degrees. This aerosol-rich veil also generated spectacular optical effects over 70% of the earth’s surface. For several years after the 1883 eruption, the earth experienced exotic colors in the sky, halos around the sun and moon, and a spectacular array of anomalous sunsets and sunrises. Artists were fascinated by these aerial displays and captured them on canvas. The painting shown here is one such sunset captured by the artitst William Ascroft on the banks of the River Thames in London, on November 26, 1883 (Courtesy of Peter Francis).

(5) Wikipedia: Eruption of Krakatoa

In the year following the eruption, average Northern Hemisphere summer temperatures fell by as much as 1.2 °C (2.2 °F).[9] Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888.[9] The record rainfall that hit Southern California during the “water year” from July 1883 to June 1884 – Los Angeles received 38.18 inches (969.8 mm) and San Diego 25.97 inches (659.6 mm)[10] – has been attributed to the Krakatoa eruption.[11] There was no El Niño during that period as is normal when heavy rain occurs in Southern California,[12] but many scientists doubt this proposed causal relationship.[13]

The eruption injected an unusually large amount of sulfur dioxide (SO2) gas high into the stratosphere, which was subsequently transported by high level winds all over the planet. This led to a global increase in sulfuric acid (H2SO4) concentration in high level cirrus clouds. The resulting increase in cloud reflectivity (or albedo) would reflect more incoming light from the sun than usual, and cool the entire planet until the suspended sulfur fell to the ground as acid precipitation.[14]

(6) USGS: Volcanic Gases and Their Effects

Examples of volcanic gas compositions, in volume percent concentrations
(from Symonds et. al., 1994)


VolcanoTectonic Style
Kilauea Summit
Hot Spot
Erta` Ale
Divergent Plate
MomotomboConvergent Plate
H20 37.1 77.2 97.1
C02 48.9 11.3 1.44
S02 11.8 8.34 0.50
H2 0.49 1.39 0.70
CO 1.51 0.44 0.01
H2S 0.04 0.68 0.23
HCl 0.08 0.42 2.89
HF 0.26

The volcanic gases that pose the greatest potential hazard to people, animals, agriculture, and property are sulfur dioxide, carbon dioxide, and hydrogen fluoride.

Carbon dioxide (CO2)

Volcanoes release more than 130 million tonnes of CO2 into the atmosphere every year. This colorless, odorless gas usually does not pose a direct hazard to life because it typically becomes diluted to low concentrations very quickly whether it is released continuously from the ground or during episodic eruptions. But in certain circumstances, CO2 may become concentrated at levels lethal to people and animals.


Mt. St. Helens, from Alaska Air. Photo by Alex Forbes



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2 thoughts on “Volcanic vs. Man-made Climate Change

  1. Ales Interesting blog, but wrong. See graph of CO2 – earthguide.ucsd.edu History of Atmosphere CO2 and The Physical Flaws of the Global Warming Theory by Dr. William Gray; Professor Emeritus, Department of Atmospheric Science; Colorado State University – paper presented at the International Conference of Science- 2012

  2. I disagree with your “wrong” conclusion, but approved it anyway. I could not find the referenced chart on EarthGuide, by search for CO2 or William Gray, nor could I find out much about who maintains the page. You are saying that Gray says, and by implication you yourself are saying, that the massive data compiled by 97% of the world’s scientists in this and related fields are wrong, but that this William Gray feller, perhaps like Sen Inhofe, has it right. So sorry.

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