Volcanoes produce less than 10% of CO2 than humanity does
I have noticed that some who hold that climate change is a liberal hoax have been arguing that volcanoes put more carbon into the atmosphere than humans. This is simply not factual. During an average year, volcanoes release between about 180 and 440 Million tons of carbon dioxide. Last year humans released 38.2 Billion tons. Back in 2003, the figures were 240 million tons from volcanoes and 27 BILLION tons from humans. I believe that someone just looked at the numbers without taking into consideration the units. Someone erroneously stated that 240 is bigger than 27 so they came to the false conclusion that volcanoes produce more CO2 than humans. But when you do the math with units (millions vs billions), volcanoes discharge less than 10% of the amount that humans release on yearly average.
There is no question that very large volcanic eruptions can inject significant amounts of carbon dioxide into the atmosphere. The 1991 eruption of Mt Pinatubo is thought to have injected more than 250 million tons of gas into the upper atmosphere on a single day. Large, violent eruptions may match the rate of human emissions for the few hours that they last, but they are too rare and fleeting to rival humanity’s annual emissions. In fact, several individual U.S. states emit more carbon dioxide in a year than all the volcanoes on the planet combined do.
The 1980 eruption of Mount St. Helens vented approximately 10 million tons of CO2 into the atmosphere in only 9 hours. However, it currently takes humanity only 2.5 hours to put out the same amount. While large explosive eruptions like this are rare and only occur globally every 10 years or so, humanity's emissions are ceaseless and increasing every year.
Volcanic activity today pales in comparison to the carbon dioxide emissions we are generating by burning fossil fuels for energy, but over the course of geologic time, volcanoes have occasionally contributed to global warming by producing significant amounts of carbon dioxide and other greenhouse gases. For example, some geologists hypothesize that 250 million years ago at the end of the Permian, an extensive flood of lava poured continually from what is currently Siberia for almost a million years. This large-scale, long-lasting basalt flood likely raised global temperatures enough to cause one of the worst extinction events in our planet's history. I discuss this in my blog called The Great Dying. Current volcanic activity doesn't occur on the same massive scale. And even at the end of the Permian, carbon emissions from the basalt flood happened over a very long time period (nearly a million yrs), while the rate of carbon emissions from humans today (almost 200 yrs) is happening at an extremely rapid rate compared to natural processes.
In addition, carbon is not the only material emitted by volcanos. Volcanos release sulfur dioxide, ash and other aerosol particles. Volcanic aerosols reflect sunlight back into space, cooling global climate. The 1815 eruption of Mount Tambora produced enough ash and aerosols to cancel summer in Europe and North America in 1816. So the relationship of volcanic eruptions to changes in the atmosphere and earth’s ecosystem is much more complex than simply how much carbon dioxide is released during a rare volcanic eruption.
Greenhouse gases in the atmosphere and oceans have shown increasing concentrations very steadily over the past couple of hundred years. This is almost entirely attributable to the burning of fossil fuels. We can tell the excess carbon comes from burning fossil fuels because of the isotopic mix of carbon in these fuels as we measure them in the atmosphere. So, to say that natural processes such as volcanic eruptions have more influence over carbon concentrations in the atmosphere than the massive amount that humans release is an uninformed notion.