Science

What’s causing Europe’s extreme summer? How the answer could lie far away over the Atlantic

Europe is sweltering through a record-breaking summer of heatwaves and drought that has parched the continent and turned forests tinder-dry. 

Wildfires are blazing across France, while Germany‘s most-important river, the Rhine, is on the verge of running dry, and swathes of England are officially in drought today. 

In this video, MailOnline’s Shivali Best explains the Azores High – a weather phenomena that is ‘driving Europe’s extreme drought’. 

The Azores High usually sits to the south but is currently directly over the UK and Ireland, stretching from the Azores Islands

Using climate models, scientists simulated global weather over the past 1,200 years and found that the number of large Azores Highs is extremely unusual

Using climate models, scientists simulated global weather over the past 1,200 years and found that the number of large Azores Highs is extremely unusual

Met Office reveals how the ‘Azores High’ pressure system is pushing up from the south and bringing scorching temperatures to the UK, France and the Iberian peninsula

The Met Office has revealed how the ‘Azores High’ pressure system is pushing up from the south, bringing scorching temperatures to the UK, France and the Iberian peninsula. 

The Azores High is a large centre of high atmospheric pressure typically found south of the Azores archipelago in the Atlantic Ocean. 

It is often referred to as the ‘gatekeeper of precipitation’, and is formed by dry air descending in the subtropics. 

What's causing Europe's extreme summer? How the answer could lie far away over the Atlantic

Flames rip through tinder-dry woodland in Gironde, in the south of France, where a record-breaking summer of heatwaves and drought has turned pine forests into firewood

The river Rhine is pictured with low water. The low water levels are threatening Germany's industry as more and more ships are unable to traverse the key waterway

The river Rhine is pictured with low water. The low water levels are threatening Germany’s industry as more and more ships are unable to traverse the key waterway

Europe is in the grips of sweltering heat, severe drought and raging wildfires that are tearing through Spain, France and Portugal, while key waterways such as the Rhine and the Po are running dry

Europe is in the grips of sweltering heat, severe drought and raging wildfires that are tearing through Spain, France and Portugal, while key waterways such as the Rhine and the Po are running dry

What is The Azores High? 

The Azores High is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores archipelago in the Atlantic Ocean. 

Formed by dry air descending in the subtropics, the Azores High, which usually sits off Spain, has grown larger and is being pushed northwards.

This has brought scorching temperatures to the UK, France and the Iberian peninsula.

The size and intensity of the Azores high shifts year on year, driving variations in rainfall levels over the continent. 

As such, it’s been referred to as a ‘gatekeeper of precipitation’ over Europe.

Source: Carbon Brief  

While it usually sits off Spain, it has recently grown larger and is being pushed further north, bringing scorching temperatures to the UK, France, and the Iberian peninsula. 

A Met Office spokesperson told MailOnline: ‘Areas of high and low pressures do move around the globe, so the Azores High does occasionally extend across the UK throughout the year. 

‘The high usually doesn’t stay for too long but on this occasion it has remained close by throughout the summer.’

Worryingly, these large Azores High systems are becoming more common.

A major new study this year found that over the past 100 years, the number of extremely large Azores High systems has increased significantly.

And since 1980, large Azores Highs are two to three times more likely than over the previous hundred years.

Using climate models, scientists simulated global weather over the past 1,200 years and found that the number of large Azores Highs is extremely unusual.

Aside from the effects of the Azores High this summer, scientists believe long-term trends in hot weather have been caused by climate change.  

The 10 warmest years on record in the UK have occurred in the 21st century, with data stretching back to 1884. 

Professor Nigel Arnell, professor of climate system science at the University of Reading, said this year’s heat was ‘virtually impossible’ without the sharp rise in greenhouse gases since pre-industrial times.

‘The implication of that of course is that droughts are going to get worse into the future,’ he said. 

Swathes of England are officially in drought today as supermarkets began rationing bottled water today to prevent panic buying and millions of households edge closer to a hosepipe ban.

Residents in the South West, Southern and Central England and East of England have been move into drought status where they are being urged to be frugal with water use because of the driest summer in 50 years.

It is the first drought declared in the UK since 2018 – although that one was rapidly brought to an end by heavy rain – but despite the threat of torrential downpours and thunderstorms on Monday, much of southern England is unlikely to see significant rain until September.

The dried out greens and fairways of Ashton Court Golf Course, near Bristol, where the prolonged dry conditions, have left the parched land turning from green to brown

The dried out greens and fairways of Ashton Court Golf Course, near Bristol, where the prolonged dry conditions, have left the parched land turning from green to brown

A view of a dry lake bed near the village of Conoplja, 150 kilometers north-west of Belgrade, Serbia

A view of a dry lake bed near the village of Conoplja, 150 kilometers north-west of Belgrade, Serbia

A prolonged period of low rainfall is a common definition of a drought, but in fact there is no one definition that applies across science, agriculture and the water industry.

‘Within agriculture, a period of three or four weeks with no or below average rainfall quickly constitutes a drought situation in this country,’ said Dr Joe Osborne, an industry consultancy manager at the Met Office. 

‘[But] there are many, many different definitions of drought, from the meteorological, the hydrological, the agricultural and the socio-economic perspectives.’ 

The move will put pressure on water companies to do more to conserve supplies after a number of major leaks in recent weeks wasting millions of gallons of water.

Hosepipe bans have already been announced for around 17million people – and another 15million could soon join them. Parts of southern England had the driest July since records began, and reservoir levels have fallen to their lowest levels in last 30 years.

Sainsbury’s and Aldi have put up posters limiting customers to between three and five bottles of drinking water each.

The ground starts to crack on a footpath in Windsor Great Park due to the continued heat and lack of rainfall on August 11, 2022

The ground starts to crack on a footpath in Windsor Great Park due to the continued heat and lack of rainfall on August 11, 2022

Dry conditions are like a ‘tinder box’ for sparking fires, as seen in parts of France at the moment. Wildfires are now blazing across the country’s southwest, forcing tens of thousands of people to evacuate from their homes. 

A wildfire starts with a spark, perhaps from a burning ember, a spark on a train track, lightning, heat from the sun or even often human error, such as disposing of a lit cigarette. 

If a spark happens in the presence of oxygen and fuel – such as dry grass, trees, shrubs and even houses – a fire can start.

During the first British heatwave of the 2022 summer, fires were reported in Upminster, Southgate, Croydon, Dagenham and the Essex village of Wennington, among other locations.  

HOW WILL A DROUGHT BEING DECLARED AFFECT BRITS?  

– What will an official drought mean for the public?

A drought might not mean much in practical terms for people’s day-to-day lives immediately, but it gives water companies the freedom to implement certain stages of their emergency plans.

Level one of most drought plans might be as simple as asking the public to voluntarily cut down on their water use, followed by restricting non-essential usage via a hosepipe ban.

As the dry weather drags on, this can be extended to a non-essential use ban on activities such as filing a pond, cleaning non-domestic premises and vehicles such as boats, aircraft or trains.

In extreme scenarios, water firms can ask permission from the Environment Agency to abstract water from lakes and rivers, and disused boreholes.

– How does climate change cause both drought and flooding in summer?

In 2021, bursts of heavy rain saw localised flooding, particularly in London, where some tube stations had to be evacuated.

Scientists warn that while climate change is likely to increase the intensity of summer rainfall, it won’t save us from future water shortages.

Prof Arnell sad: ‘As the atmosphere warms, it can hold more water, so if the conditions are triggered to generate a storm, that storm will have more water in it.

‘So the chance of having the intense sort of rainfall that we saw in London last year increases with climate change, but that’s sort of short duration one-off events which can happen during the dry period.’

He continued: ‘So the total rainfall will be less but it might be concentrated in short duration intense bursts, which will be problematic for all sorts of reasons – for short-term flooding risks and also for water resources as well.’

– Will the taps run dry this year?

While rivers and reservoirs in some areas have plunged to some of the lowest levels on record, relatively high levels of ground water have so far prevented the need for tighter water restrictions.

Mr Hannaford said there had been a ‘pulse of replenishment’ of groundwater late last year, but warned in places, particularly the chalky ground of the South East, levels were declining sharply.

‘The important point is groundwater makes a very large part of the drinking water supply across south-east England,’ he said.

Professor Arnell said that in England and Wales, communities are unlikely to see the same levels of water restrictions seen during the heatwave of 1976.

He added: ‘(The water industry) is in a much better position than it was in 1976 because it has prepared drought plans there are measures that are organised and thought about in advance.’

– What does the drought mean for the natural world?

The drought can have a devastating impact on wildlife, not just those trying to survive on tinder-dry land, but also those in freshwater and marine ecosystems as well.

Mr Hannaford said lower river flows and stagnant water leads to higher concentrations of pollutants, while dried up waterways means animals can lose access to their usual range of habitat.

‘You can get a lack of connection between those areas and that can have an impact on the life cycles of lots of aquatic organisms,’ he said.

Stagnant water also increases the likelihood of algal blooms that suck oxygen from the water, leaving fish and other fauna struggling to survive.

– What will it take to get back to normal?

‘Thundery breakdown and showers’ are forecast for the early part of next week, but it is not yet clear how much rain we can expect, or where it will fall.

But scientists agree that it will take a lot more than average rainfall to rehydrate the nation.

A burst of heavy rain will often run straight off very dry ground, potentially causing flash flooding and not necessarily replenishing soil moisture in a meaningful way.

Mr Hannaford said it would require ‘exceptional’ rainfall over the next one to three months to bring river, reservoir and groundwater levels back up to normal.

Source: PA

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