The ridiculously resilient ridge in the north east pacific is associated with a sudden shift to a negative PNA index which is directly linked to cooler summer arctic temperatures.
the existence of motive (wishing to maintain sea ice levels), and situation (a sudden and inexplicable change in jet stream patterns associated with a near permanent blocking event leading to reduced sea ice loss levels in the arctic) does not prove an act.
You can have a motive, and you can have a body, but without showing a means, you cannot solve the crime.
if, however, there was a means. . . if there was definitive proof of the existence of the technological capability to manipulate high/low pressure systems in the upper atmosphere, and maintain them over an extended period of time, then that would provide the final piece necessary to bring charges against a potential perpetrator.
After charges were brought then a trial must be conducted to prove guilt.
Good luck with that one!