Gavin Cawley explains the global carbon cycle and how human activity is causing an increase of CO2 in our atmosphere.
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Climate change is real, so why the controversy and debate? Learn to make sense of the science and to respond to climate change denial in Denial101x, a MOOC from UQx and edX.
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Andy Skuce examines how CO2 emissions from human activity compares to CO2 emissions from volcanoes and finds humans release much more. For example, global human emissions in 2012 were over 60 times greater than volcanic emissions.
About Denial101x:
Climate change is real, so why the controversy and debate? Learn to make sense of the science and to respond to climate change denial in Denial101x, a MOOC from UQx and edX.
Denial101x isn’t just a climate MOOC; it’s a MOOC about how people think about climate change.
Extended commentary by Andy Skuce:
The main reference used in this lecture for emissions estimates from volcanoes is the 2013 review paper Deep Carbon Emissions from Volcanoes by Michael Burton, Georgina Sawyer and Domenico Graniero published in the journal Reviews in Mineralogy & Geochemistry Vol. 75 pp. 323-354, 2013. http://www.minsocam.org/msa/rim/RiMG0…
The figures I quoted in the talk are central estimate numbers quoted in Table 6 and there are considerable ranges of uncertainty associated with them. Table 7 shows how estimates of CO2 emissions form subaerial volcanoes have generally increased as research progresses over time. The lowest estimate (66 Mt/yr) was from Allard in 1992 and the highest (540 Mt/yr) –the one I used–was from the 2013 Burton paper.
Table 5 in Burton et al. shows a very wide range of CO2 emission estimates from different studies of mid-ocean ridge volcanoes of 4 to 792 Mt/yr, reflecting the difficulty of making these estimates. Burton et al. use a central estimate of 97 Mt/yr, which is what I adopted. That figure came from a study by Marty and Tolstikhin (1998) of 97 ± 40 Mt/yr of CO2.
I have also included sinks of CO2 that are associated with volcanic rocks. These amount to “ingassing” of approximately 180 Mt per year from weathering of volcanic rocks on land (Dessert et al., 2003) and 150 Mt/yr of CO2 from carbonation of volcanic rocks on the sea floor (Alt et al., 1999)
In case there are objections that the reactions that absorb CO2 should not be counted in the currently active volcanic emissions balance sheet, I have used both the gross emissions of 640 Mt/yr and the net emissions of 310 Mt/yr for comparisons with human emissions. Note that the volcanic gross emissions include significant current outgassing from inactive volcanoes, so that taking account of the uptake from current “ingassing” of volcanic rocks is consistent.
All of the data on human emissions and the historical CO2 concentration observations was downloaded from the Carbon Dioxide Information Analysis Center. The data were subject to minor computation (e.g., conversion of carbon masses to CO2 masses and cumulative emissions calculations) and the observations of concentrations were corrected to an 1850 baseline. The cumulative emissions were multiplied by 40% to make a rough estimate of the atmospheric fraction (the remainder of the CO2 being taken up by oceans and the terrestrial biosphere). This is not an exact method, since the take up of a pulse of CO2 is a complex time-dependent function arising from several independent processes. The simple 40% factor used here is for illustrative purposes only. The estimates in Table 10 in Le Quéré et al. (2014) yield an average atmospheric fraction of 42% since 1870, with a range of 37-48%. Most of the uncertainty arises from the estimates of land use CO2 emissions and terrestrial CO2 sinks.
There is more detail about these calculations and assumptions in a blogpost I wrote. https://critical-angle.net/2015/04/01…
I performed a similar atmospheric concentration calculation assuming constant volcanic emissions of 310 and 640 Mt/yr. Human and volcanic emissions were then compared with observed atmospheric concentration changes since 1850, with the goal of showing how volcanic emissions are far too small to account for observations, whereas human emissions fit the observations closely, both in terms of magnitude and the shape of the atmospheric concentration curve.
I have used the term “dormant” volcano in an informal sense to mean a volcano that is no longer active but that may or may not become active in the future. Burton et al. used the term “inactive volcano”.
MYTH EXAMPLES
In case anybody thinks that I am flogging a dead horse in this lecture, below is a 2014 report of Alaska Senator Lisa Murkowski making the false claim and Mike Huebsch, an appointee of Wisconsin Governor Scott Walker making a similar assertion in 2015. http://www.adn.com/alaska-beat/articl… http://www.huffingtonpost.com.au/entr…
Students and citizens around the country and around the world are forging new means of education for the urgent task of designing the transition to a sustainable future.
Calls for an international investigation in Ethiopia have surfaced after more than 100 people were killed in demonstrations.It is a conflict that has led to 400 deaths since November, 100 of them in the last week alone, according to human rights groups.The Ethiopian government is cracking down on ethnic Oromos and Amharas, who are calling for political reforms.Human rights groups have called the reponse ruthless. And the United Nations wants to send international observers to investigate.Ethiopia has denied that request, saying it alone is responsible for the security of its citizens. But what can be done to ensure the Ethiopian government respects human rights?Presenter: Folly Bah ThibaultGuests:Getachew Reda – Ethiopian communications affairs minister.Felix Horne – Ethiopia reseracher for Human Rights Watch.Ezekiel Gebissa – Profesor of History and African studies at Kettering University.- Subscribe to our channel: http://aje.io/AJSubscribe– Follow us on Twitter: https://twitter.com/AJEnglish– Find us on Facebook: https://www.facebook.com/aljazeera– Check our website: http://www.aljazeera.com/
On May 20, 3PM EDT, join the launch of the Next System Project: http://launch.thenextsystem.org. Growing inequality, political stalemate, and climate disruption prompt an important insight. When the old ways no longer produce the outcomes we are looking for, something deeper is occurring. It is time to explore genuine alternatives and new models—“the next system.” Read the statement and add your signature at: http://thenextsystem.org
Welcome to Transition Studies. To prosper for very much longer on the changing Earth humankind will need to move beyond its current fossil-fueled civilization toward one that is sustained on recycled materials and renewable energy. This is not a trivial shift. It will require a major transition in all aspects of our lives.
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