Quick! What's the Basel Convention? What does the Aarhus Convention do? Can you get nasty bites from CITES? All of these are international environmental treaties or agreements. Environmental reporters would do well to know about them — to shed light on local stories and to find national or international news.
The problem is that there are so many binational or multinational environmental agreements (well over a thousand), and that they are usually technical and obscure.
One help for keeping track is the International Environmental Agreements (IEA) Database Project  at the University of Oregon, which keeps them all in a database and updates it often.
Some other good resources on international environmental agreements:
- The "treaty locator" at the Environmental Treaties and Resource Indicators  (ENTRI) database, part of the Socioeconomic Data and Applications Center at Columbia University.
- Wikipedia's article, "List of international environmental agreements,"  is also very useful and explanatory, linking to articles on most of the major treaties.