If you would like to export unsubscribed email addresses:

1. First go to your list,
2. Click export subscribers

    3. select from the drop down box – unsubscribed subscribers – and at least the email address:

    4. Then click export – and you'll be presented with a csv file.

The global suppression list works slightly differently. You can add to and remove from the list – but not export. You can however highlight and copy the list – and then paste it into a csv file! Which effectively exports the list for you.