Big chill the price we pay for global warming?

Dr Paul Elliott, lecturer in chemistry at the University of Huddersfield looks at the big freeze and how it fits into the controversial global warming debate

IN an age where we are always hearing about climate change and global warming, sub-zero blizzard conditions might seem contradictory.

Indeed, several climate change sceptics have already been shouting loudly that the recent weather conditions disprove global warming.

To make an important point, it doesn’t! A single cold snap does not make or break an overall trend monitored over many, many years.

Global warming is an observed and documented phenomenon with measurable temperature increases. Glaciers and sea ice has been noticeably melting over the past few decades.

But with the effects of global warming observable, could harsher winters such as the one we are experiencing be something we might expect to occur more often in the future? Paradoxically for the UK, yes they possibly could.

So how might the UK begin to experience colder snowier winters more often and the planet undergo global warming? This possible scenario was actually partly the subject of the major Hollywood movie, “The Day After Tomorrow” (even though they got the science a little wrong).

The key is in the ocean. If we look at where the UK is, we are a remarkably northern country for the relative mildness of the winters we have. Places as far north as us regularly have winters where the temperature can reach -30C. But you don’t have to be that far south to get a lot of snow either.

Washington DC it about as far north as Madrid yet often has much snowier winters than Madrid or the majority of Britain. So it’s not a simple matter of how far north or south you live.

What keeps Britain from getting so very cold in winter is a warm ocean current, the North Atlantic drift, coming from the Caribbean which passes the west coast. This is part of a much larger circulating current, the thermohaline circulations, that goes around the oceans of the whole planet.

Since the water flowing from the Caribbean is warm, lots of it evaporates resulting in more concentrated salty sea water. Because there is more salt per pint of water, it ends up being heavier or denser than the ocean water it meets when it gets towards the North Atlantic. As a result, when it cools in the northern polar regions it sinks pulling more warm salty up from the Caribbean to replace it.

The flow then turns south along the ocean floor to the Antarctic where it circulates and enters either the Pacific or Indian Oceans. There it rises to the surface again before making its way back to the Atlantic and the Caribbean to complete its circuit.

This global flow of water has a large impact on climate and weather patterns and it is this sinking of the denser water flowing northward that drives this global circulating current.

But, as we’ve said, sea and glacial ice is noticeably melting and is ending up in the ocean.

This melt water could act to dilute the dense salty water of the North Atlantic drift making it lighter so it won’t sink. If this happens, the circulating current could be cut off, and along with it the major factor that moderates the temperature of the winter in western Europe and keeps our winters mild. The result would be that while the Earth as a whole would experience an overall warming, Britain might have to contend with an annual winter deep freeze.

As with everything involved in the Earth’s climate, the ocean currents are in a delicate balance.

Therefore, exactly what may happen is difficult to predict but this scenario is a possibility.

So, it might be an idea to wrap up warm out there!