The following sources can be helpful when choosing or revising a topic (just don’t forget to also do a preemption check by searching working papers and law review articles to make sure your tentative topic hasn’t already been written on).
News sources on environmental law will include some developments in international environmental law.
News sources on international law may include developments on international environmental law.
Law blogs:
You might browse blogs on international environmental law for current issues, and environmental law blogs may also include international environmental news.
American Society of International Law blogs: ASIL Insights and International Law in Brief