Synching iCal with Google Calendar
Previously you could subscribe to a Google calendar but not sync with it from iCal the built in calendar program that comes with MacOS. That meant that you could only edit the calendar on Google but see the events both in Google and in iCal on your Mac. Now, with syncing you can make the changes in either place.
The instructions are on this google page and there’s no point in me repeating them (and if they change it’s better to have the pointer than my out of date version).
After you’ve done this and the calendars sync you might see 2 versions of your events. If you’re like me and had subscribed to that calendar, just go to the calendar under Subscriptions and Delete it.