Carbon Dioxide Emissions from Subaerial Volcanic Regions
Abstract
Focused efforts of the Deep Earth CArbon DEgassing (DECADE) research initiative [1] of the Deep Carbon Observatory has led to improved quantification of CO2 emissions from volcanoes globally. Here we present results of a new volcanic CO2 compilation [2] which builds on this initiative. Average emissions were compiled for 102 active volcanoes and 135 areas of diffuse degassing over the period of 2005-2017, including periods of repose. Decadal-scale timeseries of CO2 flux were also studied to evaluate how CO2 flux varies in time and between different volcanic settings.
While the number of active volcanoes with a measured CO2 flux increased from 33 in 2013 [3] to 102 in 2018, the cumulative CO2 emitted by the measured volcanoes has decreased by 1/3 (now 44 Mt CO2/yr vs. 59.7). As datasets grow, the long-term average emission for many volcanoes is declining, by an order of magnitude in some cases (e.g., Miyakejima), due to less bias toward eruptive periods. Our current summation of volcanic diffuse degassing is ~64 Tg/yr, which is similar to that published previously [3], but our estimate does not include arc-scale extrapolated values for Pacific regions. Our compilation highlights the important contribution of hydrothermal emissions from several large regions (e.g. Yellowstone, USA, East African Rift) to the global diffuse CO2 budget. We demonstrate that the magnitude and distribution of emissions globally from active volcanoes and diffuse degassing systems are comparable. Temporal variability of CO2 emissions was found to correlate with magma composition and activity. Emissions from active, often mafic, volcanoes with an open vent are shown to vary by orders of magnitude over short (days to years) timescales. Instead, more silicic systems often produce diffuse emissions with steadier rates in time. Volcanoes that oscillate between closed- and open-vent behavior show step-like emission rates related to magma intrusions and changes in eruptive activity. We show that the gradual release of CO2 from some inactive or dormant volcanoes can rival that of some active volcanoes when considering 20-yr timescales. [1] Fischer (2013), Mineralogical Magazine 77, [2] Werner et al. (2019) Deep Carbon, Past to Present, Cambridge Univ. Press; [3] Burton et al. (2013) Deep Carbon Emissions from Volcanoes. Rev. in Min. Geochem. 75.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V24C..03W
- Keywords:
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- 1030 Geochemical cycles;
- GEOCHEMISTRY;
- 1031 Subduction zone processes;
- GEOCHEMISTRY;
- 8414 Eruption mechanisms and flow emplacement;
- VOLCANOLOGY;
- 8485 Remote sensing of volcanoes;
- VOLCANOLOGY