You misunderstand 'global warming.' Part of the prediction was more unusual weather, more swings in weather, and more disastrous storms. Further, we experience only an infinitesimal part of the world with our own senses. What you see in Edmonton is not the whole world; on average, global temps are rising.
IOW, lots of the predictions of global warming theory have come true. That doesn't validate the whole theory, but it does make it something that warrants some acceptance.