Flooding kills eight in Lahore.

Eight people have died in the city of Lahore in Punjab Province, Pakistan, this week, as onset of the Monsoon Season caused the city recorded its most severe rains in 38 years, with 214 mm of rain falling in the 24 hours up to 8 am local time on Tuesday 3 July 2018, compared to an average of 191 mm for the entire month of July. None of the deaths has been attributed directly to drowning, but rather to building collapses and electrocution due to falling power lines.

Floodwaters in Lahore, Pakistan, on Tuesday 3 July 2018. Rahat Dar/Shutterstock.

While the exceptionally high levels of rainfall are clearly a contributing factor, the flooding has also been linked to rapid urban expansion in many area, which has led to building on areas where soil was previously exposed, reducing the ability of the ground to absorb water and leading to surface flooding.

 Floodwaters in Lahore, Pakistan, on Tuesday 3 July 2018. AFP.

The flooding also caused a series of large sinkholes to open up in the central part of the city, with the largest measuring about sixty metres across, and about six metres deep. Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace. On this occasion, however, the sinkholes are being linked to poor construction work during the city's rapid expansion.

 Sinkhole that opened up in Lahore following heavy rains earlier this week.
Arif Ali/AFP/Getty Images.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea. 

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

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Landslide kills five pilgrims in Ganderbal District, Jammu and Kashmir.

Five pilgrims were killed ad several more injured when they were hit by a landslide near the Amarnath Cave Shrine in Ganderbal District, Jammu and Kashmir, on Tuesday 3 July 2018. The incident occurred following heavy rains in the area associated with the onset of the Monsoon Season, which in Jammu and Kashmir typically lasts from July to September. Landslides are common during the monsoon season in Nepal, which lasts from May to September, with  the highest rainfall occurring in July. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

 Rescue workers carrying the body of a landslide victim off a mountain in Jammu and Kashmir on 3 July 2018. JK Breaking News.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea. 

 Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

 

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Andrias davidianus: How failure to recognise a species complex may be undermining efforts to preserve the Chinese Giant Salamander.

The Chinese Giant Salamander, Andrias davidianus, is the largest extant species of Amphibian, reaching about 1.8 m in length. It is one of only three species of Giant Salamander, Cryptobranchidae, along with the Japanese Giant Salamander, Andrias japonicus, and the Hellbender, Cryptobranchus alleganiensis, which is found in the eastern United States, which are thought to have diverged from their closest relatives during the Middle Jurassic, around 170 million years ago. The species was once widespread across China, but it's wild population is thought to have declined by about 80% since the 1950s, due to a combination of habitat loss, disease, and consumption by Humans. For this reason the species is considered to be Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species. As such the species has become a focus for conservation efforts in China, which have focused on the release of large numbers of farmed Giant Salamanders back into the wild, with over 78 000 farmed Salamanders released into the wild since 2008.

In a paper published in the journal Current Biology on 21 May 2018, a group of scientists led by Fang Yan of the State Key Laboratory of Genetic Resources and Evolution at the Kunming Institute of Zoology of the Chinese Academy of Sciences present evidence that the Chinese Giant Salamander should in fact be considered to be a species cluster (group of morphologically identical but genetically distinct species, known as 'cryptic species') rather than a distinct species, and discuss the implication of this for conservation efforts.

A Chinese Giant Salamander, Andrias davidianus, in the Shanghai Aquarium. Patrick Fischer/Wikimedia Commons.

Yan et al. collected genetic samples from 70 wild caught and 1034 farmed Salamanders from across the species' range. They found that the wild Salamanders could be grouped into five distinct genetic populations, which appear to have diverged from one-another between 4.71 and 10.25 million years ago, sufficient to be considered to be separate species under most classification systems (Humans and Chimpanzees are thought to have diverged between 4 and 13 million years ago). This is not greatly surprising, as the Salamander favour upland environments, and therefore have a scattered distribution, with wide areas in between that the Salamanders cannot easily cross. 

The farmed Salamanders, in contrast, appeared to be largely hybrids, with the majority of their DNA derived from a population in the Yellow River in Shaanxi Province, the area where they were first farmed. The ability of the separate species to hybridise is not considered surprising, as the Chinese Giant Salamander is known to be able to hybridise with the (more distantly related) Japanese Giant Salamander. However the resultant hybrid Salamanders show much lower genetic diversity than wild Salamanders, and may be less well adapted to surviving in the wild. 

mtDNA haplotype clades and genetic structure of wild-caught and farm-bred Chinese Giant Salamanders. (A) A simplified Bayesian inference tree based on concatenated mtDNA haplotypes. Numbers near branches are posterior probabilities (BPP ≥ 0.90). A–E are wild caught populations and U1 and U2 are known from farms only.  (B) Sampling sites for wild-caught individuals. Lower-right insert shows the best genetic clustering (K = 5) based on genomic SNPs from localities circled in dashed line. (C) Sampling sites for farm-bred individuals where pie charts show the proportions of mitochondrial haplotypes as grouped in (A). Lower-right insert shows the second-best cluster (K = 3; optimal K = 1) based on microsatellite data for farm-bred individuals from Guizhou (farms circled in dashed line). Colours denote cryptic species lineages. Yan et al. (2018).

Yan et al. express concern that the practise of releasing farmed Salamanders (from populations originally intended form commercial exploitation as a food animal) into the wild may have a strongly adverse effect on the wild populations, potentially leading to some species becoming extinct; indeed they could find no pure indigenous Salamanders in some tributaries of the Pearl and Yangtze rivers, where all captured individuals had mtDNA (mitochondrial DNA, which is passed on only through the female line) from Yellow River Salamanders. They recommend that in future conservationists should avoid the release of captive-raised animals until a full study of the genetic structure of the subject population is carried out.

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Seventeen dead in landslides and flash floods as Monsoon reaches Nepal.

Seventeen people have been confirmed dead and another three are missing after a series of landslide and flash floods across Nepal in the last two days. Four people, including a five-year-old child, have died in separate flood-related events in Banke district, while in Rolpa, a landslide destroyed a house, killing an eight-month-old baby, her 22-year-old mother, and a fifteen-year-old boy, and another landslip in Baglung killed a six-month-old baby and both parents.. In Kailali a 65-year-old-woman died when her house collapsed amid heavy rains, her husband was injured in the  same incident and is being treated in a local hospital. Four students were swept away by floodwaters in Parsa District, two of whom were rescued, with one confirmed dead and one still missing. Two people were swept away by floods in Sarlahi District, one of whom has now been confirmed dead and one is still missing. Another person is missing after being swept away by a flood in Tanahun District. 

The remains of a bridge swept away by floodwaters in Baglung District, Nepal, on Monday 23 June 2018. Kathmandu Post.

The incidents have been blamed on torrential rainfall that has fallen across the country in the last few days. Landslides are common during the monsoon season in Nepal, which lasts from May to September, with  the highest rainfall occurring in July. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. Landslides and floods are a problem in Nepal every monsoon season, with over 1600 people having died in such events since 2010.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea. 

 Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

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Flash flood kills radio presenter in Des Moines, Iowa.

A man has died after his car was swept away during a flash flood caused by a thunderstorm in Des Moines, Iowa, on Saturday 30 June 2018. Radio sports commentator Larry Cotlar, 66, was one of three drivers whose vehicles were swept off roads by floodwaters during the storm, and was later found dead; the other two drivers were rescued safely. The incident happened as a series of thunder storms formed across Polk and Dallas counties, with over 250 mm of rain falling in under three hours in some places, resulting in a series of flash floods across the area, with one waters exceeding five metres in places, resulting in the flooding of many roads and buildings.

Flood waters in Urbandale in Polk County, Iowa, on Saturday 30 June 2018. Megan Salois/Twitter.

Thunderstorms are caused by heating of the land or water surface by the sun, causing air to expand, and thus rise, this causes more air to be drawn in to fill the gap, which is in turn heated and rises, repeating the process and creating a cycle. As the air rises it expands, and therefore cools, losing its capacity to retain water, leading to precipitation (rainfall), with higher levels of rainfall occurring when the initial air mass is warmer and more humid.

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Asteroid 2018 MG7 passes the Earth.

Asteroid 2018 MG7 passed by the Earth at a distance of about 3 605 000 km (9.40 times the average distance between the Earth and the Moon, or 2.41% of the distance between the Earth and the Sun), slightly before 9.25 pm GMT on Saturday 23 June 2018. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2018 MG7 has an estimated equivalent diameter of 110-340 m (i.e. it is estimated that a spherical object with the same volume would be 110-340 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 600 to 88 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 1.5-5 km in diameter and devastation on a global scale, as well as climatic effects that would last years or even decades.

The calculated orbit of 2018 MG7. Minor Planet Center.

2018 MG7 was discovered on 20 June 2018 (three days before its closest approach to the Earth) by the Southern Observatory for Near Earth Asteroids Research (SONEAR) at Oliviera in Minas Gerais State, Brazil. The designation 2018 MG7 implies that it was the 182nd asteroid (asteroid G7) discovered in the second half of June 2018 (period 2018 M).

2018 MG7  has a 318 day orbital period, with an elliptical orbit tilted at an angle of 25.1° to the plain of the Solar System which takes in to 0.61 AU from the Sun (61% of the distance at which the Earth orbits the Sun and considerably inside the orbit of the planet Venus) and out to 1.21 AU (21% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in November 2017 and the next predicted in January 2024. 2018 MG7 also has frequent close encounters with the planet Venus, with the last thought to have occurred in December 2010 and the next predicted for May 2021. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2018 MG7 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid. As an asteroid possibly larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2018 MG7 is also classified as a Potentially Hazardous Asteroid.

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Austrian climber killed by avalanche in Pakistan.

An Austrian climber has died and two Britons were injured when their tent was hit by an avalanche on the Ultar Sar Peak in the Hunza Valley in Gilgit-Baltistan Province, Pakistan, on Friday 29 June 2018. The three men have been identified as Christian Huber, who died in the incident, plus Bruce Normand and Timothy Miller, who were rescued by a helicopter from the Pakistan Army and are being treated at a hospital in Islamabad. The avalanche occurred at an altitude of 5.9 km and was caused by a storm, which also hampered the rescue attempt. The helicopter crew have been commended for their actions.

Austrian climber Christian Huber who died in an avalanche on Ultra Sar on 29 June 2018. AP.

Ultra Sar forms part of the Karakorum Mountain Range, which runs through Afghanistan, Pakistan, India, Tajikistan and into China. At 7388 m it is not among the higher mountains in the range, but it is one of the most prominent, rising 5300 m above the floor of the Hunza Valley. As such it is of great interest to climbers, though it is considered an extremely difficult and dangerous ascent, with fifteen failed attempts to climb it and numerous fatalities, during the 1980s and 1990s, before the summit was eventually reached by a Japanese team in 1996.

Ultra Sar, right, foreground, with (rght to left) Bojohagur Duanasir, Hunza, and Bumblimotin behind. Wikimedia Commons.

Avalanches are caused by the mechanical failure of snowpacks; essentially when the weight of the snow above a certain point exceeds the carrying capacity of the snow at that point to support its weight. This can happen for two reasons, because more snow falls upslope, causing the weight to rise, or because snow begins to melt downslope, causing the carrying capacity to fall. Avalanches may also be triggered by other events, such as Earthquakes or rockfalls. Contrary to what is often seen in films and on television, avalanches are not usually triggered by loud noises. Because snow forms layers, with each layer typically occurring due to a different snowfall, and having different physical properties, multiple avalanches can occur at the same spot, with the failure of a weaker layer losing to the loss of the snow above it, but other layers below left in place - to potentially fail later.

 Diagrammatic representation of an avalanche, showing how layering of snow contributes to these events. Expedition Earth.

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