Impact pathway of climate change on regional dew amount variations in Central Asia

Central Asia (CA) This study focused on the impact pathways of climate change on the dew amount dynamics at the regional scale. To achieve the goal, the spatial and temporal patterns of dew amount during the growing season were reconstructed by a Random Forest model from 1970 to 2023. The impact pathways of temperature and precipitation on regional dew amount dynamics were elucidated using structural equation modeling. The multi-year average dew amount in the growing season was about 19 mm for the whole CA, with great values in the north and elevated mountainous areas. There was a significant decline of dew amount during 1970–2023, especially in May. Further, the reduction of dew amount was more pronounced in sparsely vegetated areas than that in areas with dense vegetation. Temperature exerted a direct negative effect on the growing season dew amount dynamics in nearly 90% of CA, particularly in the forestland. Nevertheless, precipitation mainly showed indirect positive impact via its regulation on surface soil moisture in 80% of CA, especially in the bare land. The above results demonstrates that climatic warming is the direct driver of growing season dew amount decline in CA, whereas precipitation regulates regional dew amount mainly via surface soil moisture. These findings may be helpful to ecological restoration in arid and semi-arid regions. • Long-term spatial distributions of dew amount in Central Asia (CA) were reconstructed using a machine learning model. • A significant decline of growing season dew amount was identified over the past five decades in 60% of CA. • Warming was the direct and dominant driver of dew amount reduction in most areas of CA, particularly in the forest land. • Precipitation exerted indirect positive effects on dew amount dynamics through surface soil moisture in more than 80% of CA.