International environmental law has been fully tied to scientific disciplines in that it relates to natural aspects of human life. Scientific features of legal discussions and legal aspects of natural sciences form the structure of environmental law. It can be argued that this field of law is the most scientific branch of law. Natural sciences play a significant role in the international environmental law, because mere legal doctrines and principles are not sufficient to eliminate and resolve the environmental challenges and problems. The assessment of the risk of harm and determination of damages caused by destructive environmental activities are not possible without scientific methods. In addition, environmental law mostly encompasses natural issues including pollution, greenhouse gas, climate change, preservation of rare species, biodiversity, and the management of water resources. Thus, it is imperfect and useless to study the environmental law without addressing natural sciences. In the present paper, challenges and solutions in respect of the linkage between environmental law and natural sciences have been overviewed.