Cleaning up birth years 2000 in my Address Book
Try:

set targetYear to "2000"
set targetGroup to {}

tell application "Address Book"
    set thePeople to every person whose birth date ≠ missing value
    repeat with aPerson in thePeople
        set birthYear to (aPerson's birth date)
        if my yearCheck(birthYear, targetYear) then set end of targetGroup to (contents of aPerson)
    end repeat
    if targetGroup ≠ {} then set selection to targetGroup
    activate
end tell

on yearCheck(theDate, theYear)
    if theYear = (year of theDate as text) then return true
    return false
end yearCheck




Added by the OP for novices like him. This works. What I did: Open Address Book, click All Contacts, close Address Book, close the Internet connection (just to be sure), copy-paste the above script into AppleScript Editor, press Compile, press Run, wait until "Running..." disappears. Address Book is now open with the cards with 2000 selected. Put those in a Group for further work...