Soil is a major contributor to global greenhouse gas emissions and climate change

Abstract

It is unequivocal that human activities have increased emissions of greenhouse gases, that this is causing warming, and that these changes will be irreversible for centuries to millennia. Whilst previous studies have broadly examined the contribution of agriculture or land use change to anthropogenic greenhouse gas emissions, the contribution of soil itself remains unclear, with quantifying the contribution of soil in this regard being critical for developing and implementing appropriate management practices. In the present study, we used previously published datasets for carbon dioxide, nitrous oxide, and methane to determine soil-based emissions of greenhouse gases and their contribution to anthropogenic greenhouse gas emissions. We show that our near-complete reliance on soil to produce the rapidly increasing quantities of food being demanded by humans has caused soil to release profound amounts of greenhouse gases that are threatening the future climate. Indeed, net anthropogenic emissions from soil alone account for 15 % of the entire global increase in climate warming (radiative forcing) caused by well-mixed greenhouse gases, with carbon dioxide being the most important gas emitted from soil (74 % of total soil-derived warming), followed by nitrous oxide (17 %) and methane (9 %). There is an urgent need to prevent further land use change (including for biofuel production) to limit the release of carbon dioxide that results from the loss of soil organic carbon, to develop strategies to increase nitrogen fertilizer efficiency in order to reduce nitrous oxide emissions, to decrease methane from rice paddies, and to ensure that the widespread thawing of permafrost is avoided. Innovative approaches are urgently required for reducing greenhouse gas emissions from soil if we are to limit global warming to 1.5 or 2.0 °C.