Well, the PDO is pretty commonly known.
It is a bit of a stretch to use it to try to attack the entire concept of global warming.
There are a variety of currents, oscillations etc. that impact climate. This is just one. There is also the NAO for one.
Oscillations are well-known and don't disprove global warming.
Oscillations and global warming are natural phenomena.
"Proving" or "disproving" such is meaningless.