Funny weather we’re having... how the melting Arctic is affecting global weather patterns in a sinister way

Submitted by Phil on Sun, 08/05/2012 - 18:56

There was a time, not long ago, when ‘global warming’, or ‘climate change’ as it became more frequently labelled, was purely a theoretical construct, a thing of the future. Disturbing, spine-chilling even, for those who understood it, it was still something quite remote, something that had to be constructed out of scientific principles which only quite a concentrated effort of intellect and imagination could convert into meaningful consequences – and those a safeish distance away, in the future.

It is still true that only a grasp of the scientific principles, an intellectual process, can convey to us the full scale of human-induced global warming and the totality of its ultimate consequences. But it now has a presence in our ‘here and now’ – it has insidiously crept into the background music of our lives. To many it does not bear the label of ‘climate change’ or any label at all, and whilst, as the Aid Agencies for instance will tell us, for some already this incomprehensible phenomena has spelt tragedy, suffering and death, for most of us, especially in the developed world, it is more of a curious, dimly perceived, novelty.
Funny weather that other people are having

Whether we’ve ever even heard the phrase ‘climate change’ or have any understanding of what that really means - or not – the dimly perceived novelty is the ‘funny weather we’re having’. It might be the funny weather on the news – the funny weather that other people are having, like the drought in the US right now, or those forest fires, in Colorado, in Spain, in Australia, in Greece in wherever-the hell next, or those torrential floods in Beijing last month or Thailand a while back, or Pakistan last year, or was it the year before, or that other drought and heat-wave in Russia a year or two ago, or the drought and consequent famine in Niger, exacerbated in short order by terrible floods, or those freezing storms in the US, or the hurricanes that seem to be getting stronger and more destructive or….And its not that any one of these things is something really new, we’ve seen extreme weather disasters, and we’ve seen exceptionally extreme weather disasters before but its just the sense that they seem to keep on coming so thick and fast, with a barely a gap, one after another, after another or even at the same time. We can all sense that - even if we are not activists who have Bill McKibben bellowing into our ears (the simple plain truth of) just how many record breaking weather disasters are happening and how statistically extraordinary this really is.
Here in the UK
Or it might be the funny weather we are experiencing ourselves. Here in the UK. Like the deluge that was this June or the deluge that was this April. Whilst they are telling us there’ll be a hosepipe ban because of too many dry winters. Or the bite-your toes off cold snap of December (not January – December!) 2010, or the freezing winter before it. Or the eerie sense that the seasons aren’t quite right with Spring far too early or maybe summer or autumn too late.
We knew this was going to happen….
Now those of us who are climate-science nerds can say we understand this and not only that but we knew this was going to happen. We knew that a warmer world would mean, on average, earlier springs and later autumns. We knew that a warmer world would be a world with more energy all round, and more ‘energy’ would mean more violent, more extreme, weather. Stronger storms, stronger cyclones, happening more frequently. And more heat would mean more evaporation which would mean more precipitation which would mean more and worse floods. Even when, in other places, or even in the same place but at different times, more heat would mean more dryness and drought.
But just in case there might be any doubt James Hansen has come up with a study to prove statistically what common sense would in any way suggest – namely that the weather extremes we’ve seen – especially those involving extreme heat – have to do with global warming. He’s dodged the question about whether a particular event is caused by global warming and asked the more meaningful question “what are the chances it would have happened without global warming ?” He comes up with the answer (validated by a rigorous statistical study) that extreme events for which there used to be a 1 in 300 chance of happening have a 1 in 10 chance, now. No way is this ‘natural variability’: it has to be climate change.
Still plenty of surprises
And yet there are still plenty of surprises and discomfiting asymmetries in the way things are panning out even for the clever-cleverest of climate nerds, or, indeed, even for the most brilliant of climate scientists when it comes to giving a precise explanation for a specific event. The extreme cold snaps, for instance, are an obvious gift for the sceptics – “if the world is warming why is it so b****ing cold ?”. Well, we can reach for the global temperature map and say, look, whilst its exceptionally cold here, its actually exceptionally warm over there (see eg this temperature anomaly map for December 2010 with a frigid Western Europe but an exceptionally warm western Greenland) : what really matters is the average temperature around the world, not just localised phenomena. And not only that but its not the occasional variations that make up our weather that are significant, it’s the average over a significant amount of time that defines our climate.
A more meandery jet stream.
And yet we may still be left wondering – just why was there such a cold snap, just here at just that time. And not only that but the meteorologists didn’t seem to be helping very much attributing as they did many of the extreme weather patterns to the behaviour of the ‘jet stream’ that super strong high altitude current of air that defines the boundaries of separate (vast) masses of air. “Not climate change!” the sceptics were sneering “but the jet stream!”.    The Russian heat-wave, we were told was caused because the jet stream got “stuck” in a certain configuration, a” blocking pattern” it was called …and because it was stuck that meant that weather that would normally last just a few days went on for weeks or even months, so that in Russia, for instance, temperatures mounted and mounted to produce a record-breaking heatwave. Or conversely in the UK this June and April the jet stream got stuck in a pattern that was bringing cyclonic rainy weather to our shores, on and on and on ….until it became a record rainy month, with all the attendant flooding that you’d expect.
But there was more to it than that – the jet stream was getting ‘stuck’ because it was a weaker, more sluggish, jet stream. And a weaker, less powerful, jet stream is also a more meandery jet stream – just a like a river which is a powerful and relatively direct ‘torrent’ in the mountains near its source but as it slows down and loses energy on the plain, so it meanders more, too. In the case of the jet stream the direction of the flow is predominantly West-East (it's this West –East flow that defines the boundaries of the Arctic and mid latitude air-masses for instance) – so that more meandering means more than normal North-South ‘wobbles’ or movements of air. This was the cause of the cold Arctic air finding its way unusually far South to the UK and Western Europe in December 2010 just as it was the cause of the warm air finding its way unusually far North to Western Greenland at the same time. The deep ‘meanders’ formed a wave pattern with the crest of the warm air, South of the jet stream, reaching high up into Greenland and the trough of the cold arctic air mass, North of it, descending unusually low into Western Europe (see for instance the illustration in this article or the animation in this one). Similarly another crest of warm air pushing unusually far North gave the US an exceptionally mild winter this year, as well as a drought this summer (aided by the Pacific “El Nina”) and it was hot dry African air pushing unusually far North that was associated with the Russian heatwave just as, at the same time a counter-part meander of the jet stream brought colder moist air unusually far South to Pakistan to combine with the monsoon in producing the exceptional and devastating Indus valley floods of 2010.
“Arctic amplification”
Now it was always fair to say that all such phenomena would always be rendered more extreme for the classic reason that global warming means there is more energy in the system but recent studies have pointed to a more meaningful and direct connection between this unusual behaviour of the jet stream and climate change. This has to do with a well known feature of global warming – that is that, for a variety of reasons it's happening more quickly in the Arctic, than just about anywhere else (“Arctic Amplification” as it’s termed). But the well witnessed exceptionally rapid warming of the Arctic – something that is creating an ‘Arctic Emergency’, all of its own – is not just restricted to the Northern polar latitudes in its impacts. Already, even back in 2010 some studies were suggesting a link between the localised  exceptional-cold-period phenomena further South and what was happening in the Arctic. It's now suggested that  the slower, less powerful, more meandering jet stream has to do with the reduced temperature gradient between the mid latitude and the arctic air masses caused by the disproportionately rapid warming of the latter. It was the steep temperature gradient and resultant big pressure differences that powered the jet stream, the current of air at the borders of those air masses – and so with less temperature difference there was a less powerful, more meandery, jet stream.
This is to put the theory in its simplest form.  Here’s quite a good summary and there are also a great couple of videos that can explain all of this much better than I can, here (Part 1) and especially here (Part 2).
I think its important that if this persuasive explanation is correct then – as far as I am aware – it's not something that anyone, not any of the clever climate scientists, predicted. There is no avoiding of course the fundamental thrust of the scientific predictions – more warming, more energy in the system, more frequent and more extreme severe weather. But within that general pattern there may be all manner of surprises, very likely unpleasant surprises. 
No going back
And one thing about the ‘funny weather’ that is counter-intuitive we should not forget. Departures from the norm are more often than not temporary ( after all that’s what makes ‘the norm’, the norm). But we will never see ‘normal weather’ – in the sense of the kind of weather we were used to, over significant periods – again. There is no going back, the weather will only get more weird, not less. We have started to slither down a slippery slope and there is no scrambling back up it.
And the ‘funny weather’ has a dark and sinister side. The Russian drought of 2010 provoked Putin to place an embargo on grain exports which resulted in a steep rise in prices that led to food riots in places like Mozambique. This showed that wherever the actual axe of freak weather falls it will be the world’s poorest (wherever they are) who will suffer most. We haven’t yet seen the full knock on effects of the US drought on food prices (and consequently on levels of political instability around the planet). But some of the predictions are dire. So we can already see this ‘funny weather’ feeding into the gathering of that ‘perfect storm’ of crop failures, rising food prices, deepening poverty, hunger and ultimately mass starvation.
But for most of us in the developed world these will be far-off calamities to which we may become inured as they gradually increase in severity. And certainly for the moment it is more than anything just a consciousness of the ‘funny weather’, a vague sense of something slightly, insidiously, different and new. Like the unexpected but faint, ambiguous, touch of a hand to your throat, you could say, before it reveals itself to be that of a murderer, gripping ever tighter till it has squeezed your breath away.