A warming climate will make Australian soil a net emitter of atmospheric CO2

• Published in: NPJ climate and atmospheric science 2024-03, Vol.7 (1), p.79-11, Article 79
• Main Authors: Viscarra Rossel, R. A., Zhang, M., Behrens, T., Webster, R.
• Format: Article
• Language: English
• Subjects: 704/106/694/2739/2807; 704/172/4081; 704/47; Agricultural land; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Carbon dioxide; Climate change; Climate Change/Climate Change Impacts; Climate policy; Climatology; Coastal zone; Earth and Environmental Science; Earth Sciences; Economic conditions; Emissions; Emitters; Endemic plants; Global warming; Greenhouse effect; Greenhouse gases; Indigenous plants; Land management; Organic carbon; Organic soils; Pasture management; Plant communities; Rangelands; Socioeconomics; Soil conservation; Soil temperature; Soils
• ISSN: 2397-3722; 2397-3722
• DOI: 10.1038/s41612-024-00619-z

Understanding the change in soil organic carbon (C) stock in a warmer climate and the effect of current land management on that stock is critical for soil and environmental conservation and climate policy. By simulation modeling, we predicted changes in Australia’s soil organic C stock from 2010 to 2100. These vary from losses of 0.014–0.077 t C ha −1 year −1 between 2020 and 2045 and 0.013–0.047 t C ha −1 year −1 between 2070 and 2100, under increasing emissions of greenhouse gases and temperature. Thus, Australian soil will be a net emitter of CO 2 . Depending on the future socio-economic conditions, we predict that croplands will accrue as much as 0.19 t C ha −1 year −1 between 2020 and 2045 due to their management, but accrual will decrease with warming and increased emissions by 2070–2100. The gains will be too small to counteract the losses of C from the larger areas of rangelands and coastal regions that are more sensitive to a warmer climate. In principle, prudent management of the rangelands, for example, improving grazing management and regenerating biodiverse, endemic native plant communities, could sequester more C and mitigate the loss; in practice, it may be more difficult, requiring innovation, interdisciplinary science, cultural awareness and effective policies.