There is a Google sync add-on for Mozilla Thunderbird's calendar add on called Lightening (all free) that will sync that calendar to Google calendar. The only thing you can't do is sync tasks - though there is also an add on for that but it did not work very well. It means giving up on Outlook.
Google Calendar Sync for Outlook has not been available for download for some time. (I tried two or so years ago to get it and couldn't.) Interesting that they are now pulling the plug so that those who had it cannot use it any longer. This has been part of the dispute between Google and MS and the users are the ones who lose out.