Mason is right, they can't/refuse to climb backwards.
This same thing happened to a neighbor's cat about 4 years ago. No matter what the old woman did, the can would not come down.
First, get the owner out of the area. Then, get two pairs of guys with blankets ready under the tree. Third, knock the cat down, catch it in a blanket.
I say two pairs of guys because we tried it with 4 guys, each with a corner of a big comforter, and it is just too tough to coordinate moving around in the 1 second that you have before the cat hits the ground. We failed in trying to catch it in the blanket but we managed to break its fall enough that it was not injured. He sort of bounced off one end of the blanket.
Unfortunately, your tree sounds REALLY tall.
[ 01-08-2002: Message edited by: Mickey1992 ]