Critical resources for environmental studies in the UPSC syllabus include the NCERT textbooks, which provide a foundational understanding. Key reports such as the Economic Survey and the Environment and Forests Statistics offer updated statistics and governmental policies. Aspirants can benefit from the IPCC reports and UN publications for a global perspective. Online platforms like PMF IAS and preparation apps also offer specialized study materials and current affairs updates, ensuring candidates have comprehensive resources to tackle environmental issues effectively in the exam.