Year: 2025
Type: dissertation
Abstract: Volcanoes play a dual role in the global carbon cycle, acting as both short-term sources and long-term sinks of atmospheric CO₂. During eruptions, magma degassing releases large volumes of CO₂ into the atmosphere. In the aftermath of basaltic eruptions, the exposed lava begins to weather chemically, initiating silicate weathering reactions that gradually consume atmospheric CO₂. This study investigates the timescale required for Fagradalsfjall 2021 lava field to transition from a carbon source to a sink. The lava field was mapped out using satellite imagery, resulting in an area of approximately 2.8 km2 and an estimated volume of 144 million m3. Based on typical basaltic lava contents, total CO2 emitted was estimated to be between 0.81-2.4 Mt. Two weathering models were applied to estimate the rate of carbon drawdown via silicate weathering. One field-based empirical weathering rate and a lab-based dissolution rate of basaltic glass. These methods resulted in weathering rates of 0.312 and 12.2 mol·m⁻²·yr-1. Total surface area were estimated using a geometric model applied on the lava morphology. The weathering rates were applied to the specific surface area resulting in a source to sink time of 4500-14000 years and 230-700 years depending on method used. The results indicate that climate and lava morphology influence weathering rates. Depending on local response times, lava fields may be buried before transitioning into a carbon sink. This highlights the importance of including eruption frequency, surface morphology, and chemical reactivity when assessing volcanoes impact on earth’s climate.
Author: Lemnert, Leo
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W6983588825