An interesting debate involving both scientists and climate change sceptics alike focuses on the emission of CO2 from volcanoes. During eruptions, CO2 is emitted, having the potential to promote global warming. Scientists, such as Robin Wylie from University College London state how, before anthropogenic changes to the earth, CO2 changes were largely controlled by volcanic activity. At present, it is difficult to know just exactly how much CO2 is produced by volcanoes, but even those considered inactive can still make serious contributions to the atmosphere through ‘diffuse CO2’ (see page 3). When taking this into account, new studies have shown that volcanic degassing contributes much more to global CO2 than previously thought. In 1991, volcanic degassing was estimated to release 79 million tonnes of CO2 each year - a recent study by Burton (2013) places this figure at around 540 million tonnes. More data needs to be collected, but the results are clear: volcanic activity is significant. Indeed, this data is being pushed by climate change sceptics like Australian Geologist Ian Plimer, who argue that volcanoes release more CO2 than human activity; in particular submarine volcanoes, of which little data has been collected.
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| Volcanic eruptions: a huge emitter of atmospheric CO2? Source |
However, even with the new 540 million tonne estimation, volcanic activity still pales in comparison to data released for human emissions of CO2 - estimated at just shy of 40 billion tonnes a year in 2013. This dwarfs the annual CO2 emissions of all the world’s degassing subaerial and submarine volcanoes (Gerlach, 2011). While atmospheric concentrations have stayed between 190-280 parts per million (ppm) for the last 400,000 years (Zeebe and Caldeira, 2008), it recently peaked at 400ppm in 2015. It is my opinion that this information debunks the theory of volcanic activity contributing more CO2 than anthropogenic climate change.
It would be great to hear what you think on this - do you think there is enough evidence to be sceptical of anthropogenic climate change due to volcanic CO2 emissions? Let me know!
I think that there is definitely not any evidence to be sceptical of anthropogenic climate change, particularly not from volcanic emissions. Like you said, the emissions really dwarf in comparison to our emissions. Volcanoes will have erupted throughout history and their CO2 emissions have never lead, to our knowledge, to unprecedented rises in global temperatures the way we are seeing today.
ReplyDeleteTrue - but I think it's very important to challenge these climate change sceptics as, surprisingly, they hold a lot of influence over public opinion and ultimately policy making. Take Ian Plimer, for example, he is a professor of Earth Sciences at the University of Melbourne, so holds a large amount of influence! But yes, I totally agree with you on this!
DeleteHi Celia, A very interesting blog as usual! It is interesting you looked at volcanoes, as this has been the source of inspiration to develop aerosols in the atmosphere as an SRM process to mitigate climate change impacts. However, I strongly disagree that volcanoes release more CO2 than human activity, people have overpassed 400ppm that has not occurred before. I believe only if there were continual volcanic eruptions of high CO2 content for a certain period of time this could surpass anthropogenic CO2. Yet I still highly doubt that could happen.
ReplyDeleteThanks for your comment! It is a very interesting theory, isn't it - although it has been largely discredited. It's interesting you highlight volcanoes as a source to mitigate climate impacts, volcanic activity has such a broad range of impacts! Yes, I agree, it is very unlikely that the conditions under which the CO2 emitted from volcanoes would match anthropogenic emissions would prevail.
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