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| Titel |
Modeling volcanic eruptions to assess the impact of stratospheric sulfur injections on the global carbon cycle |
| VerfasserIn |
Thomas L. Frölicher, Fortunat Joos, Christoph C. Raible |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043794
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| Zusammenfassung |
| Injecting sulfate aerosols precursors into the stratosphere has been proposed to mitigate
anthropogenic climate change. Volcanic eruptions could serve as a testbed to estimate the
potential of geoengineering efforts related to direct manipulation of solar energy
input via aerosols. Understanding how volcanoes affect the global carbon cycle and
climate could lead to valuable insights into the response of the coupled carbon
cycle-climate system to chronic sulfur loading. Major volcanic eruptions can dramatically
increase the sulfate aerosols in the stratosphere having several impacts on surface
climate. For example, the eruption of Mt Pinatubo was followed by a decrease in
global surface solar radiation, temperature and precipitation including drought in
South-East Asia, and an increase in diffuse solar radiation, North Hemispheric winter
temperature and terrestrial carbon uptake. Yet, the regional impacts of volcanic
eruptions on the global carbon cycle and the connection to initial conditions remain
unresolved.
We assess the short- and long-term impacts of volcanic eruptions with the NCAR
CSM1.4-carbon model on both the global and regional scale by performing a suite of
sensitivity simulations. The coupled carbon cycle-climate model allows us to investigate the
full radiative and dynamical response to volcanic eruptions. First, we use an ensemble of six
transient simulations from 1820 to 2100 to show that the composite mean decrease in ocean
temperature leads to significant carbon uptake on the regional scale, mainly in the tropical
Pacific Ocean, although globally negligible. Additionally, we run one transient simulation
over the period 1820 to 2100 without volcanoes. Although volcanic eruptions produce mainly
short-term transient atmospheric climate perturbations which last for 2-3 years, the ocean
integrates volcanic radiative cooling, and dissolved inorganic carbon and oxygen changes
could last well into the 21th century. Second, we run several sensitivity experiments
(i) starting from different coupled modes (El Niño vs. La Niña), (ii) starting in
different seasons (winter vs. summer), and (iii) using different eruption locations
(high vs. low-latitude). We show that the response of volcanic eruptions highly
depends on the initial conditions with higher atmospheric CO2 response starting the
simulations in El Niño winter season. Finally, we scaled the Mt Pinatubo eruption to
investigate the impact of supervolcanoes. Results show that atmospheric surface
temperature and CO2 do not linearly decrease with the amount of stratospheric
aerosols.
We conclude that geoengineering by means of stratospheric sulfate aerosols could have
adverse effects on regional scale and depends largely on the location of injection and the state
of the climate system. Furthermore, geoengineering techniques will not significantly reduce
atmospheric CO2 levels and therefore fail to address the wider effects of rising CO2 including
ocean acidification. |
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