I'm not a climate change denier, but there is definitely the potential for at least some of the change to be related to cyclical events.
But it's also a vicious circle. Assuming that the vast majority of greenhouse gas emissions have been a result of human activity, the rise in atmospheric and especially sea temperatures causes an increase in the amount of carbon dioxide and methane (a far more potent greenhouse gas than CO2) that is released from the depths of the oceans, leading to increased atmospheric temperatures, and so ad infinitum.
In fact, i have just read that water vapour is the most dominant greenhouse gas in the atmosphere - that is also going to increase in proportion to rising temperatures.
We're all doomed!!