You can share a portal's events calendar by choosing the Subscribe option in the top right of the Events tool. This will generate a pop-up that provides sharing options to several external calendars, including Google Calendar, Outlook, iCal, and into other forms like an RSS Feed, .ics file, and iframe.
You can also export your personal events, which includes events from your various memberships and events you've RSVP'd to. Click on your name in the top right of the screen, choose Events, then select the Subscribe option in the top right of the page.
To import a single event occurrence, select the event from your event calendar and locate the export options under the date and time.