Diatoms are ubiquitous across vast habitats and highly sensitive to environmental changes. Thus, these photosynthetic microbial eukaryotes are often considered as indicators of environmental health. In the prevailing climate change and its consequential impacts, periodic monitoring of the environmental changes and their impacts on terrestrial ecosystems is inevitable. Ecological models and indices based on diatoms were used by environmentalists all across the globe to monitor aquatic health and trophic status of both marine and freshwater. On the contrary, terrestrial diatoms and their autecology were not explored much. This chapter discusses the potential of terrestrial diatoms as biological indicators, specifically to assess the impacts of climate change.