Response of Northern Hemispheric climate and Asian monsoon to dust darkened snow cover changes during the Last Glacial Maximum

Eolian dust darkens the snowpack, accelerates the snowmelt and alters atmospheric radiative budget and climate. Last Glacial Maximum (LGM), a typical geological cold stage, is featured by more dust and snow cover than present day, which seems to own a stronger snow-darkening. In this study, we used a couple of climate model experiments in order to evaluate the effect of dust-in-snow changes on Northern Hemispheric climate and Asian monsoon. The results show that, compared to present day, more dust and snow cover in LGM allows heavier dust deposition and snowmelt, which produces a larger snow-albedo-temperature feedback. This snow-darkening leads to an annually averaged northern hemisphere warming of 0.31 °C, stronger in boreal spring and summer. Spatially, the prominent warming centers are found around LGM ice sheets and Tibetan Plateau (TP), up to 2–3 °C annually, which significantly contributes to the melt of ice and triggers the termination of glaciation. Over Asia, the present snow-darkening weakens the Indian and East Asian summer monsoon although not significant. However, strong LGM forcing does not amplify the weakening but intensifies the Indian and East Asian monsoon and precipitation. Thus, the potential role of dust and its interaction with snow cover should be mentioned in the glacial-scale climate change.