A Cold Snap IS NOT Evidence Against Climate ChangeAt this time of year, as temperatures cool and the snow begins to fall, out come the sceptics who claim that since it's cold, climate change must not be happening. Really? I'm not going to get into the physics of why we have seasons but what I will say is that unless temperatures rise by a couple of dozen degrees, there will always be places on Earth that experience snow in Winter.
Climate statistics are based on the average temperatures across whole years, which clearly show a steady rise in global temperature. Accurate statistics abound but here is a very clear graph of England's temperature trends since the 19th century.
Then there is the issue of unexpectedly cold weather, such as we have been experiencing in the UK this winter. This can be explained very simply by viewing a map and knowing a little about how the gulf stream works. If you look at a map you will see that we are on a similar latitude to Canada, Russia and other places we all know get seriously cold in the Winter. The reason that we avoid the extreme weather is the Gulf Stream which is a warm ocean current that brings us heat from the tropics. The Gulf Stream is the major factor in our climate, but unfortunately it is also rather sensitive, particularly to the salination level (saltiness) of the sea. The ice caps are primarily composed of fresh water so as they melt they 'dilute' the sea, lowering the salination level and impeding the flow of the Gulf Stream and preventing it from warming us up as effectively.
For more info on the Gulf Stream see the BBC Weather Centre.