I agree that it doesn't look like much of a barrier, but there also appears to be a wire running along the top and possibly through the fence. So the bear would probably get a shock if he tried to test the barrier.
have a look at the South Lakes Zoo gallery in UK, built by the same guy (David Gill) the general enclosure design and construction is very similar. Very interesting to read the history of this (Cairns) zoo and its owners....