Europe’s most active volcano, Mount Etna, has been hitting the headlines recently after a series of spectacular eruptions. In Etna’s first eruption of 2021, explosive lava fountains reached over 1500 m in one of the most amazing eruptions in decades.

Mount Etna, Sicily, erupting in February 2021

Mount Etna, located on the island of Sicily, has been largely dormant for the past two years. The stratovolcano (composite) dominates the skyline of the Italian island, where it sits on the eastern coast.

Located between the cities of Messina and Catania, it is the highest active volcano in Europe outside the Caucasus – a region between the Black Sea and the Caspian Sea – and the highest peak in Italy south of the Alps.

The recent activity is typical of a strombolian eruption among the normal activities of the more than 3,300-metre-high volcano. The recent eruption is the strongest explosion in the southern crater since it was discovered in 1971.

On Monday 22nd February 2021, at around 11 pm, the lava fountains, surrounded by gigantic clouds of smoke, exceeded 1,500 metres (4,900ft) in height, while thousands of rock fragments, some the size of fridges, were thrown from the crater into the sky for several kilometres.

Etna is a hyperactive volcano with over 3,500 years of historically documented eruptions. The volcano has been erupting on and off since September 2013. Since September 2019, it’s been erupting from its various summit craters virtually continuously. In December 2020, Etna’s explosive activity and lava output began to spike, and in February 2021, it has been launching fluid lava skywards.

Etna is an unusual volcano in that it can produce explosive eruptions of runny lava and release slower flowing, thick lava flows. Scientists are still trying to work out why this is the case.

The magma from the latest eruption appears to be coming up from deep within the mantle. Extremely hot, fluid magma is rapidly rising through the network of conduits within and below the volcano. However, there is another factor that is contributing to the current explosive eruptions.

There are high quantities of water vapour in Etna’s magma, which makes it explosive. The water does not cool the magma. As the molten magma approaches the surface, the pressure drops, and the bubble of water vapour expands violently, leading to lava being ejected out of the volcano.

Following each explosive lava fountain, less gassy magma lingers just below the vent. This is then cleared when a new volley of gassy magma rises from below. These explosive eruptions are known as volcanic paroxysms.

Authorities have reported no danger to the nearby towns, however, local airports have been temporarily closed, as has the airspace around the volcano. Etna’s last major eruption was in 1992. Despite the explosive nature of the recent eruption, there is no risk to the population, other than from the ash that covers buildings and smoke that can, after a few hours, cause breathing problems. In March 2017 vulcanologists, tourists and a BBC film crew were injured during an eruption when a flow of lava ran into snow, producing superheated steam that sent fragments of rock flying in all directions.

Further reading

For a Volcanologist Living on Mount Etna, the Latest Eruption Is a Delight – Advisory – this article contains expletives (swear words).

In Pictures: Mount Etna eruption lights up Sicily’s night sky

Mount Etna: BBC crew caught up in volcano blast

Mount Etna illuminates night sky with 1,500-metre lava fountain

Storm Christoph is the third named storm of the 2020/2021 season and the first of 2021, following Storm Aiden on October 30 and Storm Bella on Boxing Day 2020.

Storm Christoph was a slow-moving Atlantic depression, which brought a variety of weather to the UK between the 19th and 21st of January 2021. The storm system moved across the UK from west to east.

#StormChristoph comes in two main phases…

PHASE 1 – Tues to Thurs 💦
Heavy rain brings flooding N Eng & Midlands.

PHASE 2 – Thurs ❄️💨
Heavy snow and stronger winds (blizzards) in Scot and N and NE Eng. pic.twitter.com/qtGSatxPVm

— Simon King (@SimonOKing) January 19, 2021

Unlike the low-pressure systems that often affect the UK at this time of year, Storm Christoph’s main threat was heavy rainfall, rather than strong winds.

The map below shows flood warnings and the places with the most rainfall from Storm Christoph.

Storm Christoph rainfall and flood warnings – source

Preparation for Storm Christoph

An Amber National Severe Weather Warning for rain was issued for parts of northern and central England. Separate Yellow warnings for rain, wind, snow and ice covered large areas of England, Scotland, Wales and Northern Ireland.

The Environmental Agency and Met Office issued a series of warnings about Storm Christoph.

Flood Guidance Statement issued by the EA and Met Office

More than 400 flood warnings and alerts were issued across England. In Wales, 15 flood warnings and 53 flood alerts were in place.

The Prime Minister, Boris Johnson, advised people to act if instructed to evacuate.

Storm Christoph flood warnings

Local authorities issued warnings to local residents.

Officers from Wigan Council, Greater Manchester Police, Greater Manchester Fire & Rescue Service and health services have worked together to respond to hundreds of calls and mitigated dozens of flooding incidents this week as a result of #StormChristoph pic.twitter.com/qiTSUCzOPx

— Wigan Council (@WiganCouncil) January 21, 2021

Several steps were taken to prepare areas previously affected by flooding. Fishlake, near Doncaster, was one of the worst affected areas in floods in November 2019. On Tuesday 19th January, residents readied themselves for their village to flood a second time in just over two years.

What were the effects of Storm Christoph?

Areas of the UK was hit by heavy rain, snow and flooding that has led to towns and villages being cut off and a major incident declared in South Yorkshire and Greater Manchester.

The northwest of England and the north of Wales were some of the worst affected areas as properties submerged as rivers burst their banks, and drainage systems failed to cope with the torrential downpours brought by Storm Christoph.

#StormChristoph is expected to bring up to 200mm of rain for parts of the UK this week. Stay in touch with the forecast here: https://t.co/iy7JDPLcWC pic.twitter.com/Bp4aKVCi9A

— BBC Weather (@bbcweather) January 18, 2021

The Cheshire village of Lymm, a village of 12,000 people located 7 miles away from Warrington, experienced flooding. However, this was not on the same scale as the floods of November 2019. Although fewer than a dozen homes were submerged in the end, for many of those, it was the second such disaster in less than two years.

Around 400 homes were flooded as a result of Storm Christoph, the Environment Agency has confirmed.

Around 26,000 homes were protected from the various flood defence assets distributed by the Environment Agency. 600 people were on the ground, putting up temporary barriers, using pumps in Manchester areas with particular flood challenges.

Firefighters and police evacuated 2,000 homes and businesses in south Manchester on January 20 with 3,000 properties said to be at risk.

Houses on Walmer Street in Abbey Hey, Manchester fell into a giant sinkhole following heavy rainfall.

Manchester sinkhole

In Maghull in Merseyside and Ruthin, North Wales, families were also forced out of their homes due to rising floodwaters.

Travel suspensions were placed on services from Carlisle to Skipton or Maryport, all destinations from Rotherham Central, and between Manchester and Newton le Willows.

Rail services between Warrington Central and Liverpool Lime Street, Altrincham to Chester, and Wigan to Southport were also suspended. Rail services between Leeds and York via Garforth were disrupted due to flooding in the Garforth area, with bus services replacing trains throughout the day.

In South Wales, water built up in a mine shaft causing a “blow out” that flooded properties in Skewen, Neath Port Talbot. At least 80 people had to leave their homes in the village after flooding.

North Yorkshire County Council said more than 15,000 sandbags were at the ready around the county.

Flood plains near Cawood in North Yorkshire, have been storing vast amounts of water as rivers rose rapidly following Storm Christoph’s heavy rainfall. These are shown in the video below.

Population Changes in South Korea

South Korea’s birth rate has fallen for the first time in its history. As a high-income country, South Korea is battling an ageing population and low birth-rates.

An ageing population is when more people than ever live longer, often with more complex medical conditions. An ageing population increases the dependency ratio and means that the government has to pay more in benefits to people who often do not have the ability to pump money back into the economy.

The latest census (a count of all people and households) figures indicate South Korea’s total population stood at 51,829,023 at the end of December 2020. This is a reduction of 20,838 from the previous year.

Over the previous decade, South Korea’s population had increased every year, although that growth rate had decreased by 1.49% in 2010 to 0.05% by 2019.

During 2020 the country recorded 275,815 births in 2020, compared with 307,764 deaths.

If current trends persist, the government predicts South Korea’s population will drop to 39 million by 2067, when more than 46% of the population will be aged over 64.

Demographic transition

The animation below shows changes in South Korea’s population structure between 1950 and 2019. The animation clearly shows an increase in life expectancy (more people living to an older age) and a decrease in the proportion of younger people (as the birth rate decreases).

South Korea is undergoing an extreme, rapid example of what demographers (people who study population) call ‘demographic transition’. This is a period of population growth, decline and eventual stabilisation that occurs as countries get richer. For South Korea, this means both a large, rapidly ageing population and a low marriage and birth rate that don’t adequately replace the dying generations.

The demographic transition model attempts to show the population changes a country experiences as it develops.

In later stages of the demographic transition, health care improvements generally lead to a population with an extended life expectancy. That is exactly what is happening in South Korea, where life expectancy has increased rapidly in the second half of the 20th Century amid industrialisation.

In the first half of the 1950s, life expectancy was just shorter than 42 years on average (37 for men, 47 for women). Today, the numbers look radically different. South Korea now has one of the world’s highest life expectancies – ranked twelfth highest for 2015-2020, equal with Iceland. The average baby born in South Korea can now expect to live to 82 years (specifically 79 for men, and 85 for women).

In contrast, the global average is 72 years (nearly 70 for men, 74 for women).

In 1950, less than 3% of the population were aged 65 and over. Today, that number is at 15%. By the mid-2060s, the UN forecasts the percentage of those older than 65s will peak at more than 40%. The numbers paint a picture of a very aged society.

And with low birth rates, fewer marriages and longer lives, the trends combine to create a South Korean population that is actually ageing faster than any other developed country.

Why is South Korea’s population in decline?

South Korea has the lowest fertility rate in the world.

The average South Korean woman has just 1.1 children, lower than any other country. (For contrast, the global average is around 2.5 children.) This rate has been declining steadily: between the early 1950s and today, the fertility rate in South Korea dropped from 5.6 to 1.1 children per woman.

One reason for this is because, in South Korea, women struggle to achieve a balance between work and other life demands.

It has been suggested there is increasing opposition among South Korean women to conform to traditions of raising children and caring for ageing in-laws while husbands work.

South Korean women aren’t simply choosing to have fewer children – some are opting to forego romantic relationships entirely. An increasing number are choosing never to marry at all, turning their backs on legal partnerships – and even casual relationships – in favour of having independent lives and careers in what can still be a sexist society despite economic advances.

Soaring house prices are another major issue. Rapidly rising property prices mean a greater proportion of income is spent on mortgages. Also, young couples are put off having children because they are expensive to raise.

What issues are associated with a declining, ageing population?

Apart from increased pressure on public spending as demand for healthcare systems and pensions rise, a declining youth population also leads to labour shortages that directly impact the economy.

What is South Korea doing to address the issue of a declining, ageing population?

Like Japan, which also has a declining population, the government is under pressure to address the long-term issues caused by a rapidly ageing society.

The South Korean government recently announced initiatives to encourage couples to have bigger families, including a one-off payment of 1m won (£675) for pregnant women and monthly cash allowances for children aged under 12 months.

However, critics say the measures do little to tackle much bigger financial obstacles to having more children, such as high education and housing costs.