* Is part of a proper noun:
* Global Positioning System (GPS)
* Global Warming
* The Global South
* The Global Village
* Is used as an adjective in a title:
* Global Issues in International Relations
* The Global Impact of Climate Change
* Global Perspectives on Education
* Is used in a specific context where it refers to a particular organization or event:
* The Global Summit on Climate Change
* The Global Fund to Fight AIDS, Tuberculosis and Malaria
You do not capitalize "global" when it is used as a general adjective:
* The global economy is facing challenges.
* We live in a globalized world.
* Global warming is a serious threat.
Essentially, you capitalize "global" when it is part of a specific name or title, and you leave it lowercase when it's used generally.