Just because its 'the natural cycle of things' doesnt mean it doesnt exist. Climate does change all the time. During Roman times, in what is now the UK, it was a lot warmer. The Romans were able to grow and harvest grapes outdoors as far north as Lincoln. We're only just starting to get those conditions back now.
Apparently, listening to a programme on Radio 4 a few weeks ago, the best guess is that by 2080, temperatures in the UK might rise by 4.5 degrees. Now, to me, that doesnt actually sound a lot, given all the talk of panic and imminent end of the World that has been widely forecast. Ok, most of us wont be around in 2080, but that actually sounds quite pleasant to me.