So it’s a new year, and already here in the UK we are seeing some fairly extreme weather. At least it’s extreme in UK terms that is. With going on for three weeks of freezing temperatures, snow, cancelled trains and planes, you would think that most people have enough to worry about just getting to work (or the pub even..). I was out and about on the farm the other day, just admiring the spectacle of about 2,000 Pink-footed geese trying to select a landing spot, circling around the fields like vultures, eyeing up any potential site with the smallest morsel of tasty grass to nibble on, when the phone rang. It was my mum, reporting in with tales of schoolboy snowball fights on her street and Postal workers struggling to deliver her precious junk mail, when all of a sudden, quite out of the blue she said ‘So much for global warming then!’. I laughed, and skirted around the issue simply because I knew that to get into a discussion on the finer points of climate change cause and effect with my mother would cost me most of the next hour. And it was minus 7 (celsius) and I’m in a field.

 Now I would expect that kind of comment from my mum, but this past couple of weeks I have had various snippets of 'doubt on the matter of climate change' from folks who really should know better. I was starting to get a tad frustrated with the constant need to explain that weather does not equal climate and that the fact that you have a burst water pipe and mild frostbite does NOT mean that ‘this climate change malarkey’ is not happening after all. I mean, come on..

Anyway, as is often the case on these matters, help arrived in the form of Pete Smith, our 1E Environment Strategist. He had obviously been experiencing the same inane and tedious climate change denial rumblings and had put together an email with excellent information as to just where all of this chilly weather was coming from. So I felt that I must share it with the world, in the hope that anybody out there who is plagued by questions of this nature will be armed with the finest information to hand. Take it away Pete...

Actually, your current UK conditions are directly related to a number of climate systems prone to being thrown out of whack by global warming - El Nino, the jet stream, and the gulf stream

Factor 1.  El Nino. An El Nino event occurs when average sea surface temperatures are more that 0.5 degrees above average - some areas are hitting 3 degrees now - a massive El Nino.  For the UK, this means colder weather.  Interesting to note that this follows the strongest La Nina event for 20 years last year - it has gone from one extreme to the other in just 12 months.

(One scenario is that El Nino becomes permanent over the next 30 years - bit of a problem if you live in India, as this means the monsoon moves into the Bay of Bengal - so permanent drought)

Factor 2.  Jet stream shift event - normally in winter, the jet stream curves around the top of Scotland and acts as a thermal barrier to polar air reaching the UK.  At the moment, there is a shift in the mid Atlantic, which means the jet stream pushes south to curve around the bottom of the UK - allowing cold arctic air to flow south, resulting in your current temperatures.  This is (was) a very rare event.  The last time it really hit hard was in 1957 - when sub zero temperatures lasted until May.  The jet stream is affected by El Nino, and also by higher global temperatures pushing more energy into it - making its location less predictable and possibly less stable. 

(One scenario is these events become much more common, making European winters much harsher)

Factor 3.  30% reduction in the strength of the Gulf Stream since the 1950's.  Climate change is changing ocean circulation, which is the most significant factor in determining regional climate.  Less energy in the gulf stream is a symptom of this, and will result in a general cooling of winters in Europe.

If you want to see the science for yourself  you can go to http://www.esrl.noaa.gov/psd/enso/