Digital soil mapping (DsM) techniques combined with space-for-time substitution (sFTs) processes were used to map and examine soil organic carbon (sOC) changes caused by projected climate change over New south Wales, Australia until ~2070. Twelve projections were derived from four global climate models downscaled with three regional climate models. A marked variation in the direction and magnitude of sOC change was demonstrated with the different projections. Mean state-wide predictions (0-30 cm depth) ranged between 2.9 Mg ha -1 gain and 8.7 Mg ha -1 sOC loss. Greater consistency among climate change projections is required before we can confidently predict sOC changes. By using averaged results from the 12 projections, broad trends were revealed for the change in sOC over two intervals (0-30 and 30-100 cm). A mean loss rate of 2.0 Mg ha -1 for the upper interval was demonstrated and a total loss of 737 Tg of CO 2 equivalent for the entire depth to 100 cm but the 95% confidence interval was wide. Although changes are primarily controlled by the balance between changing temperatures and rainfall, the extent of change also depends on the environmental regime, with differing changes demonstrated over 36 current climate-parent material-land use combinations (e.g., projected mean sOC decline is <1 Mg ha -1 for dryhighly siliceous-cropping but >15 Mg ha -1 for wet-mafic-native vegetation C limate change will impact on many aspects of the global environment and civilization generally, with changes in our soil resources being one important yet not widely understood consequence. Changes in key soil properties such as SOC content will influence agricultural productivity and our ability to feed and support the growing world population. Native ecosystems will be impacted, with modifications to species distribution and abundance at local, regional, and national scales. Changes in the potential of soils to sequester C or release it to the atmosphere are crucial for climate change modeling and mitigation strategies (Lal et al., 2007;Baldock et al., 2012).Although there has been widespread work on the relationship of climate to soils, dating back to the pioneering work of Dokuchaev in 1899 (Dokuchaev, 1967 transliteration) andJenny (1941)
Core Ideas• Potential changes in soil organic C to 2070 mapped (100-m grid) and examined.• The direction and magnitude of change varied between the 12 climate projections.• Differing changes revealed for 36 current climate-parent material-land use regimes.• Digital soil mapping-space-for-time substitution is useful for climate change study