Amplifying feedback loop between drought, soil desiccation cracking, and greenhouse gas emissions

Vahedifard, Farshid, Goodman, C Clay, Paul, Varun and AghaKouchak, Amir, (2024). Amplifying feedback loop between drought, soil desiccation cracking, and greenhouse gas emissions. Environmental Research Letters, 19(3), 19 031005-n/a

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  • Sub-type Journal article
    Author Vahedifard, Farshid
    Goodman, C Clay
    Paul, Varun
    AghaKouchak, Amir
    Title Amplifying feedback loop between drought, soil desiccation cracking, and greenhouse gas emissions
    Appearing in Environmental Research Letters
    Volume 19
    Issue No. 3
    Publication Date 2024-03-05
    Place of Publication Bristol
    Publisher IOP Publishing Ltd
    Start page 19 031005
    End page n/a
    Language eng
    Abstract The continuous escalation of carbon dioxide (CO2) emissions into the atmosphere is recognized as the primary catalyst for anthropogenic climate change. In 2021, CO2 emerged as the predominant contributor to the warming effect of all human-made greenhouse gases (GHGs), accounting for two-thirds of their global heating impact [1]. While the primary anthropogenic source of increased atmospheric CO2 concentration is the combustion of fossil fuels, the largest terrestrial source of CO2 emissions is soil [2] where 80% of the total terrestrial carbon is stored. Approximately 62% of soil carbon is in organic form and readily released as CO2, while the remaining is made up of inorganic carbon (soil inorganic carbon (SIC)) [3]. Here, we postulate that there is an amplifying feedback loop between drought, soil desiccation cracking, and CO2 emission in a warming climate (figure 1)—a critical aspect that has been overlooked in the existing literature. Further, we argue that the postulated feedback loop affects the emissions of other GHGs, such as methane (CH4) and nitrous oxide (N2O), from soils. The urgent need to recognize and characterize this exacerbating feedback loop is twofold. Firstly, it is widely acknowledged that drought accelerates the oxidation of soil organic carbon (SOC) and, thus, increases CO2 emissions into the atmosphere. Drought-induced soil moisture deficits differentially affect plant processes; while photosynthesis rates may be reduced in plants, leading to decreased carbon uptake, respiration rates can vary. Initially, drought may cause a slight increase in respiration, despite a decline in photosynthesis, leading to increased carbon emissions from the soil. These effects can differ based on ecosystem types, highlighting the complex interplay between drought, photosynthesis, and respiration. Secondly, drought triggers soil desiccation cracking, substantially increasing the permeability of the soil and the interfacial exchange area between the atmosphere and the soil, which, in turn, can considerably increase CO2 efflux in soil by exposing deeper and older stores of soil carbon. Desiccation cracking threatens earthen infrastructure systems and the natural environment. The problems associated with desiccation cracks are becoming more prevalent as anthropogenic climate change exacerbates the severity and frequency of droughts, heatwaves, and drought-heavy precipitation cycles [4]. As the warming trends continue, more (and possibly older) CO2 is released from the soil, which can further contribute to global warming. Thus, a chain of events happens in a cascading manner. Failure to consider the hypothesized feedback loop can result in significant inaccuracies when modeling and predicting GHG emissions from soil. It may also lead to underestimating the overall impact of climate change on critical aspects such as soil health, crop production, and the structural integrity of earthen infrastructure.
    Copyright Holder author(s)
    Copyright Year 2024
    Copyright type Creative commons
    DOI 10.1088/1748-9326/ad2c23
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    Created: Thu, 26 Sep 2024, 05:03:05 JST by Haideh Beigi on behalf of UNU INWEH