The Special Topic on Atmospheric Compositions and Climate Change under Asian Network on Climate Science and Technology (ANCST) is coordinated at Universiti Kebangsaan Malaysia. This Special Topic encompasses the existing networks and regional initiative on the effect of chemicals in the atmosphere towards climate variability. This topic is devoted to capability building through research and education related to emission of chemicals into the atmosphere from both natural and anthropogenic sources. It is also devoted to building modeling capability and capacity with a primary focus on chemical emission and chemicals transport for air quality as well as climate forecasting within different regions. Activities implemented by this Special Topic include workshop and training, join research and publication, exchange students and sharing common data between researchers in the field.