International Environmental Law (IEL) is concerned with the attempt to control pollution and the depletion of natural resources within a framework of sustainable development. It is a branch of public international law - a body of law created by states for states to govern problems that arise between states.
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: