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.

 
 
 
 

How can cities become more bike friendly? The Netherlands offers useful lessons

(Aurore Belot/AFP via Getty Images)

It might seem like cycling is in the DNA of the Netherlands, a country where even the prime minister takes his bicycle to work. But the Dutch haven’t always lived as one with their bikes. In the Amsterdam of the early 1970s, cars were considered the wave of the future. They can be seen filling up squares and streets in historical photographs, and killed an average of over two Amsterdammers per week, including many children.

It is nothing more than an “accident of history” that the Netherlands embraced cycling, says Marco te Brömmelstoet, the director of the Urban Cycling Institute in Amsterdam and a man better known as the city’s cycling professor. Today’s bike rider’s paradise was created after parents and activists took to the streets to protest “child murder” by car. A Saudi oil embargo, rising gas prices, concerns about pollution and anger about the destruction of entire neighbourhoods to build motorways did the rest. 


Amsterdam, 1958. Not a cyclist's paradise. (Keystone/Getty Images)

What’s important about this history is that it can be replicated in other cities, too. Of course, the Netherlands has certain advantages – it’s flat as a pancake, for example. But in the eyes of traffic reformers, the rise of e-bikes (and even cargo bikes) means there’s no excuse for prioritising cars everywhere. 

So how can cities, flat or not, follow Amsterdam’s path to creating places where cycling is a pleasant, safe and common way to get around? The Dutch have some tips. 

Separate bikes from car traffic

Any city could start painting dedicated bike lanes on the streets. But in the Netherlands, those white marks indicating space for cyclists are considered just a minor first step. 

“A line on the road is not enough. Motorists will ignore it,” says Frans Jan van Rossem, a civil servant specialising in cycling policy in Utrecht. If other cities want their residents to choose bikes instead of cars when dodging pandemic-era public transport, protecting them from fast-moving car traffic must be the priority, Van Rossem says. 

The Dutch research institute CROW developed a widely praised design manual for bicycle infrastructure, full of tips for creating these protected lanes: A row of vertical white posts or a curb can serve as a physical separator, for example. Still, cyclists tend to feel safest in a "solitary" path, separated from the road by grass, trees, or an elevated concrete island. 

“The main bottleneck, the main reason why people don’t cycle, is that they don’t feel safe,” Van Rossem notes. “To start, construct separate paths.”

Turn those bike paths into a network

Many cities may have some bike lanes on some streets, but leave cyclists to roll the dice everywhere else. Will conditions still be safe when they turn left or right? Often they have to continue their way without any protected facilities for cyclists. 

“In many cases, cities take fast action, without thinking it through very well,” says Lucas Harms. He leads the Dutch Cycling Embassy, a partnership between the Dutch government and several companies, which promotes Dutch bike knowhow globally. “Don’t build small pieces of bike lane from nothing to nowhere. Think about a network of cycling infrastructure.” 

Utrecht aims to have cyclists within 200 to 300 metres of a connected path anywhere in the city, Van Rossem says. Avoid constructing those paths in sketchy industrial areas, he warns. “A connection through an unattractive area may be fast, but won’t be used a lot.”

Embrace the ‘fietsstraat’, a street where bikes come first


On some streets, drivers have to give up their privileges. (Rick Nederstigt/AFP via Getty Images)

A peculiar Dutch invention called "fietsstraat" (cycling street) holds strong potential for the rest of the world, Kevin Krizek says. He’s a transportation professor from Colorado who spent three years at Radboud University in Nijmegen. 

On cycling streets, cars are “guests”, restricted by a speed limit of 30 kilometres per hour. Drivers are not allowed to pass, so cyclists comfortably dominate the road. In the Netherlands the fietsstraat is usually paved with red asphalt, to resemble a bike path and notify drivers of their secondary status. But creating a cycling street can be easy. “All you need to do is put signs at intersections,” Krizek says. The effect is revolutionary in his view. Drivers have to give up their privileges, and cyclists can take the lead. 

Some Dutch traffic experts worry the cycling street won’t work if a city doesn’t also have a robust cycling culture. In the Netherlands, drivers are aware of the perils of urban cycling because they too use bicycles. Moreover, Dutch cities use sophisticated “circulation plans” to direct cars away from city centres and residential areas, onto a few main routes. 

Without “calming” traffic this way, the cycling street could be a step too far, Harms says. “In a city like New York, where all roads are equally accessible and full, it’s better to separate bicycles and cars,” he says.

Redesign intersections for cyclists' safety

If cyclists have to cross intersections “at the mercy of the Gods”, you’re not there yet, says Harms. When he travels abroad, he often finds clumsily designed crossings. As soon as cars turn, cyclists may fear for their lives. 

Harms recommends placing physical barriers between cars and bikes in places where they must cross. The Dutch build elevated islands to direct traffic into separate sections. The golden rule: cars wait behind bicycles. That way, drivers can see cyclists clearly at all times. Barriers also force Dutch cyclists to turn left in the safest way possible. They cross the street first and wait for their turn again before making their way left.

“You can create that with simple temporary measures,” Harms says. Planters work fine, for example. “They must be forgiving, though. When someone makes a mistake, you don’t want them to get seriously injured by a flower box’s sharp edge.”

Professor Krizek points out how the Dutch integrated cycling routes into roundabouts. Some are small; some are big and glorious, like the Hovenring between Eindhoven and Veldhoven, where cyclists take a futuristic-looking roundabout lifted above the highway. Most of those traffic circles move high volumes of cars and cyclists through intersections efficiently and safely. For a simpler solution, the Dutch manual suggests guiding cyclists to quieter streets – crossing a block up or down may be safer. “Nobody knows how to do intersections better than the Dutch,” says Krizek. 

Ban cars, or at least discourage them


A man rides down from a three-level bicycle parking garage near Amsterdam's main train station. (Timothy Clary/AFP via Getty Images)

The quickest, most affordable way to make a city more bikeable is to ban cars, says Ria Hilhorst, cycling policy advisor for the City of Amsterdam. It will make streets remarkably safe – and will most likely enrage a significant amount of people. 

Amsterdam doesn’t outlaw cars, but it does deliberately make their owners feel unwelcome in the historic city’s cramped streets. Paid parking is hugely effective, for example. Many car owners decide to avoid paying and use bicycles or public transportation for trips into the city. Utrecht, meanwhile, boasts the world’s largest bicycle parking garage, which provides a dizzying 12,500 parking spots.

To further discourage drivers from entering the city’s heart, Amsterdam will soon remove more than 10,000 car-parking spaces. Strategically placed barriers already make it impossible to cross Amsterdam efficiently by car. “In Amsterdam, it is faster to cross the city on a bike than by car,” Harms says. “That is the result of very conscious policy decisions.”

Communicate the benefits clearly

Shopkeepers always fear they will lose clients when their businesses won’t be directly accessible by car, but that’s a myth, says Harms. “A lot of research concludes that better access for pedestrians and cyclists, making a street more attractive, is an economic boost.”

Try replacing one parking space with a small park, he recommends, and residents will see how it improves their community. Home values will eventually rise in calmer, bike-friendlier neighbourhoods without through traffic, Van Rossem says. Fewer cars mean more room for green spaces, for example.

“I often miss the notion that cycling and walking can contribute a lot to the city. One of the greatest threats to public health is lack of exercise. A more walkable and bikeable city can be part of the solution,” says Ria Hilhorst. “But in many countries, cycling is seen as something for losers. I made it, so I have a car and I’m going to use it, is the idea. 

“Changing this requires political courage. Keep your back straight, and present a vision. What do you gain? Tranquility, fewer emissions, health benefits, traffic safety, less space occupied by vehicles.” 

Again, she points to Amsterdam’s history. “It is possible; we were a car city too.”

Karlijn van Houwelingen is a journalist based in New York City.