Global patterns of directed soil moisture influence on air temperature

Abstract. Soil moisture regulation of near-surface air temperature is essential for improving global climate prediction skill. Yet conventional statistical methods are often insufficient to establish causality, and the dominant pathways of this coupling remain poorly understood at the global scale. Here we combine multiple datasets with the information flow method to quantify the effects of soil moisture on temperature. We find that significant soil moisture–temperature causality exists over about 37 % of the global land area. This causality is dominated by the evaporative and sensible heat pathways, affecting 33.5 % and 18.5 % of land area, respectively, while both pathways co-occur over an additional 7.6 % of land area. In addition, these strong causal relationships are mainly driven by soil moisture variability, while most CMIP6 models tend to overestimate the likelihood of such coupling. Our study identifies the main characteristics of land–atmosphere interactions from a causal perspective and provides an important scientific basis for improving land-surface processes in future climate models.