The ‘Beast from the East’ and the freakishly warm Arctic temperatures are no coincidence

Frozen: the Kennet & Avon canal, Bath. Image: Getty.

During the past few weeks, bitterly cold weather has engulfed the UK and most of Northern Europe. At the same time, temperatures in the high Arctic have been 10 to 20°C above normal – although still generally below freezing.

The co-occurence of these two opposite extremes is no random coincidence. A quick climate rewind reveals how an unusual disturbance in the tropics more than a month ago sent out shock-waves thousands of kilometres in all directions, causing extreme weather events – not only in Europe and the Arctic, but in the southern hemisphere too.

The outbreak of cold weather across the UK was publicly forecast at least two weeks in advance. In early February, meteorologists noticed a large-scale weather event developing 30km high in the Arctic stratosphere, whose effects on our less lofty weather systems are well understood.

The strong westerly winds, known as the Polar Vortex, that normally circle the Arctic at this altitude had begun to weaken and change direction. Extremely cold arctic air – usually entrapped by this 360° barrier – was able to spill out to lower latitudes, flooding across Siberia.

Meteorologists refer to this type of event as a Sudden Stratospheric Warming (SSW) because the air in the stratosphere above the North Pole appears to warm rapidly. In fact, the cold air isn’t itself warming up so much as flooding south and being replaced by warmer air from further south.

Current air temperatures in the Arctic are much higher than recent historical averages. Image: Zachary Labe.

Changes to wind directions and temperatures 30km above the ground initially went unnoticed to those on the ground – both in Europe and in the Arctic. But over a period of several weeks, the influence of this weather event moved gradually downwards through the lower region of the atmosphere, eventually changing weather patterns near the surface.

One such change was the development of high pressure across Scandinavia, which generated easterly winds across the whole of Northern Europe, pulling cold air from Siberia directly over the UK. Out over the Atlantic Ocean the same area of high pressure resulted in southerly winds allowing warm air from the Atlantic to move northwards into the Arctic basin. Research shows that these weather shifts tend to be fairly persistent once they do occur – hence the unusual length of the cold spell we’re experiencing, and the warmth in the Arctic.

But what caused the stratospheric Arctic warming event to happen in the first place? For this we need to look thousands of kilometres away to the atmosphere above the tropical West Pacific Ocean. In late January, a vast area of thunderstorms, as large and strong as have ever been recorded, were disturbing the atmosphere across this region. The effect of these storms was equivalent to the dropping of a large boulder into a pond – they caused waves of alternating high and low pressure to spread through the atmosphere, particularly into the northern hemisphere. It was these waves bumping into the vortex of winds around the North Pole that caused the Sudden Stratospheric Warming event in early February.

The very same area of thunderstorms across the tropical Pacific acted as the birthplace for the less-reported Cyclone Gita, which tracked through the South Pacific, causing damage in Tonga and Samoa and even leading to unseasonably stormy weather across New Zealand at the end of their summer.


The near simultaneous occurrence of all of these extreme weather events is a perfect meteorological illustration of the butterfly effect. While we usually talk about weather in local and regional terms, the atmosphere is one continuous fluid expanse. Disturbances in one region are bound to have consequences to the weather in other parts of the world – and when they are severe the shock-waves can be immense.

Many have linked the severity of these events with climate change. But, particularly for this event, its important for us meteorologists to exercise caution. The occurrence of this particular stratospheric warming event is not itself a consequence of climate change, as one extreme weather event on its own does not tell us anything about long-term trends in the Earth’s climate.

What’s important is to look at how often these events occur – and how severe they are when they do. However, the series of events that lead to cold weather over Europe are complex and have only been well understood for the past 20 years or so. Without a few more decades of data, it is difficult to say whether either the stratospheric warming or the intense tropical storms are part of a pattern that falls outside of what we would normally expect – though limited research does already suggest that Stratospheric Sudden Warming events are becoming more frequent.

The ConversationFor other extreme weather events, the story is clearer – evidence increasingly suggests that hurricanes, storms and wildfires are becoming both more frequent and more severe than they once were. Time will tell if its the same story for Stratospheric Sudden Warming and tropical disturbances.

Evidence from these recent temperature extremes will certainly help researchers to understand this question. But if we do what we can to minimise the damaging impacts of climate change, we may never need to find out.

Peter Inness, Lecturer in Meteorology, University of Reading.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

When should you forget the bus and just walk?

Might as well talk, tbh. Image: Getty.

It can often be tempting to jump on a bus for a short journey through the city, especially when it’s raining or you’re running behind schedule. Where there are dedicated bus lanes in place, it can feel as though you speed past gridlocked traffic. But as city authorities begin new initiatives to get people walking or cycling, that could all change – and so could you.

British people are wasting tens of hours in traffic every year: London comes top, with the average commuter spending 74 hours in traffic, followed by Manchester, with 39 hours and Birmingham and Lincoln, both with 36 hours.

It might surprise some people to learn that cities are intentionally slowing down private vehicles, in order to shift people to other, more efficient, modes of transport. In fact, Transport for London removed 30 per cent of the road capacity for private vehicles in central London between 1996 and 2010. That trend continues today, as the organisation gives over more space for buses, cyclists and pedestrians.

London’s road capacity, over time. Image: Transport for London/author provided.

Clamp down on cars

The loss of road capacity for cars has occurred across most UK cities, but not on the same scale everywhere. The good news is that the changes, when made, appear to have reduced actual car congestion. It seems that by making it less attractive to use your car, you’ll be more likely to use other transport. In fact, the average speed of buses and cyclists can be up to twice as fast as normal traffic in cities such as London.

The relationship between walking and improved health has been proven to such an extent that it seems everyone – your doctor, your family, regional and national government – wants to increase physical activity. The savings in health care costs, are via improved fitness, reduced pollution and improved mental health, and its impact on social care are huge.

For instance, Greater Manchester wants to increase the number of people who get the recommended level of exercise (only about half currently do). The most advanced of these plans is London’s, which has the specific goal of increasing the number of walks people take by a million per day.

So, the reality is that over the next few years, walking will gradually appear more and more “normal” as we are purposefully nudged towards abandoning our rather unhealthy, sedentary lifestyles.


The long journey

Consider this: the typical bus journey in the UK is almost three miles, with an average journey time of around 23 minutes. The equivalent walk would take approximately 52 minutes, travelling at just over three miles per hour. It seems obvious that the bus is much faster – but there’s much more to consider.

People normally walk at least a quarter of a mile to and from the bus stop – that’s roughly ten minutes. Then, they have to wait for a bus (let’s say five minutes), account for the risk of delay (another five minutes) and recover from the other unpleasant aspects of bus travel, such as overcrowding.

This means that our 23 minute bus journey actually takes 43 minutes of our time; not that much less than the 52 minutes it would have taken to walk. When you think of the journey in this holistic way, it means you should probably walk if the journey is less than 2.2 miles. You might even choose to walk further, depending on how much value you place on your health, well-being and longevity – and of course how much you dislike the more unpleasant aspects of bus travel.

The real toss up between walking and getting the bus is not really about how long it takes. It’s about how we change the behaviour and perceptions we have been conditioned to hold throughout our lives; how we, as individuals, engage with the real impacts that our travel decisions have on our longevity and health. As recent converts to walking, we recommend that you give it a go for a month, and see how it changes your outlook.

The Conversation

Marcus Mayers, Visiting Research Fellow, University of Huddersfield and David Bamford, Professor of Operations Management, University of Huddersfield.

This article is republished from The Conversation under a Creative Commons license. Read the original article.