Recently, I have been trying to sync my iPod Calendar with my Google Calendar. I have found some troubles along the way because it seems that there is no app from Google that you can use to sync all your iPod Calendar to Google Calendar.
I try to find some solutions and came across the site from Google to be it up. The sync for Google Calendar can be found in this link. After you set it up, I cannot simply sync all my existing calendar to Google Calendar. It only works for all the additional Calendar that you input after setting up the sync system.
So, if you want to back up the rest of you existing Calendar data, then all you need to do is sync your iPod/iPhone to the your iTunes then choose to sync it to your iCal/Outlook. After you have sync it, export it to a back up file in .ics format. The next thing that you need to do is use the back up file and import it your Google Calendar account and voila, your iPod/iPhone Calendar data will be backed up to the Google Calendar. Hope this helps 😀