I need to contact some Iranian or Pakistan terrorist, or maybe some ex-director of a Russian nuclear plant, to get me some radioactive stuff.
Then I will deposit the thing over the Etna volcano, in Sicily, that is still active. Then I will blow the damn thing up, after hiding in a deep hole in the ground or behing a blackened glass, protected also by the energy of my rage. The explosion will propel millions of tons of debris up in the sky, and the sun will be obscured. The temperature will suddenly drop, the winds will blow, the ice age will be close again.
At that moment, I will put my beanie on, will pack the car and will go bouldering, finally with good conditions.