The potential impacts of a sulfur- and halogen-rich supereruption such as Los Chocoyos on the atmosphere and climate

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Brenna, Hans, Kutterolf, Steffen, Mills, Michael J., Krüger, Kirstin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications (EGU) 2020
• Subjects: Arctic; Sea ice
• Online Access: https://oceanrep.geomar.de/id/eprint/49919/; https://oceanrep.geomar.de/id/eprint/49919/1/acp-20-6521-2020.pdf; https://oceanrep.geomar.de/id/eprint/49919/2/acp-20-6521-2020-supplement.pdf; https://doi.org/10.5194/acp-20-6521-2020

The supereruption of Los Chocoyos (14.6°N, 91.2°W) in Guatemala ∼84kyr ago was one of the largest volcanic events of the past 100000 years. Recent petrologic data show that the eruption released very large amounts of climate-relevant sulfur and ozone-destroying chlorine and bromine gases (523±94Mt sulfur, 1200±156Mt chlorine, and 2±0.46Mt bromine). Using the Earth system model (ESM) of the Community Earth System Model version 2 (CESM2) coupled with the Whole Atmosphere Community Climate Model version 6 (WACCM6), we simulated the impacts of the sulfur- and halogen-rich Los Chocoyos eruption on the preindustrial Earth system. Our simulations show that elevated sulfate burden and aerosol optical depth (AOD) persists for 5 years in the model, while the volcanic halogens stay elevated for nearly 15 years. As a consequence, the eruption leads to a collapse of the ozone layer with global mean column ozone values dropping to 50DU (80% decrease) and leading to a 550% increase in surface UV over the first 5 years, with potential impacts on the biosphere. The volcanic eruption shows an asymmetric-hemispheric response with enhanced aerosol, ozone, UV, and climate signals over the Northern Hemisphere. Surface climate is impacted globally due to peak AOD of >6, which leads to a maximum surface cooling of >6K, precipitation and terrestrial net primary production decrease of >25%, and sea ice area increases of 40% in the first 3 years. Locally, a wetting (>100%) and strong increase in net primary production (NPP) (>700%) over northern Africa is simulated in the first 5 years and related to a southward shift of the Intertropical Convergence Zone (ITCZ) to the southern tropics. The ocean responds with pronounced El Niño conditions in the first 3 years that shift to the southern tropics and are coherent with the ITCZ change. Recovery to pre-eruption ozone levels and climate takes 15 years and 30 years, respectively. The long-lasting surface cooling is sustained by an immediate increase in the Arctic sea ice area, ...