IEL covers topics such as population, biodiversity, climate change, ozone depletion, toxic and hazardous substances, air, land, sea and transboundary water pollution, conservation of marine resources, desertification, and nuclear damage.
(Source: Lakshman D Guruswamy, International Environmental Law in a Nutshell (West, 5th ed, 2017)). For more information and a good introduction to the topic, see: