Hi guys I had this problem and it was driving me crazy.
I will say before hand I have Time Machine running and will assume you all keep your systems backed up too!!
After fixing the problem I did lose all recurring and future events but I have got them back through Time Machine.
Anyway…
1) Go in to Calendar. Select each of your iCloud calendars then choose File>Export)
Export your iCloud calendars to desktop. (Work, personal etc) don't change the name.
2) Go to Finder>Go (whilst holding option key) select Library.
--The next step is to reinstall future/recurring events
3) Make a copy of folder Calendar.
4) Log-in to iCloud.com and select calendar
5) create a new calendar called 'test' or something.
6) Delete your iCloud Calendars from iCloud (be brave!)
7) Create new calendars in iCloud.com calling them the same name they were before, they will obviously be empty.
8) Open Calendar on your Mac. Your new empty calendars should be there waiting for you.
9) Double click on your exported calendars on the desktop from earlier and select the appropriatete calendar when prompted.
That should be it.
Now as I said when I checked my calendar after this there were no future events. I reinstalled the calendar folder from Time Machine but the copy we made earlier should be fine.
a) Go to Finder>Library (as in step 2 above)
b) Delete Folder Calendar
c) Rename your Calendar Copy folder (from step 3 above) back to calendar
Hope this helps. My calendar is back to normal
You may want to try the following to clean up your calendars http://support.apple.com/kb/TS4337?viewlocale=en_US&locale=en_US