عربي English Türkçe اردو فارسى
Logo
Latest News
Varieties

Scientists Reveal Secrets of Desert Star Dunes

A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
TT
TT

Scientists Reveal Secrets of Desert Star Dunes

A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS

They are among the wonders of our deserts: star dunes, the vaguely pyramid-shaped sand formations up to about 1,000 feet (300 meters) tall with arms stretching out from a central peak to give them a star-like appearance when viewed from above.
Scientists on Monday unveiled the first in-depth study of a star dune, revealing the internal structure of these geological features and showing how long it took for one of them to form - more quickly than expected but still a process unfolding over many centuries.
The study focused upon a star dune in eastern Morocco called Lala Lallia, meaning "highest sacred point" in the local Berber language, situated within the Sahara Desert in a small sand sea called Erg Chebbi about 3 miles (5 km) from the town of Merzouga, close to the border with Algeria.
Lala Lallia rises about 330 feet (100 meters) above the surrounding dunes and is approximately 2,300 feet (700 meters) wide, containing about 5-1/2 million metric tons of sand.
According to Reuters, he researchers used ground-penetrating radar to peer inside the dune and employed luminescence dating to determine how long Lala Lallia has taken to form, a method based on the amount of energy trapped inside the grains of sand. The answer: about 900 years, accumulating roughly 6,400 metric tons annually as wind relentlessly blows sand through the desert.
Star dunes make up just under 10% of the dunes in Earth's deserts and are the tallest ones, surpassing other types such as crescent-shaped barchan dunes and straight and lengthy linear dunes. They also have been spotted on Mars and on Saturn's large moon Titan.
"I first encountered star dunes in Namibia 20 years ago, and was instantly amazed at the size of them. I have a vivid memory of the long climb to the top, struggling up very loose sand in the heat of the day," said geographer Geoff Duller of Aberystwyth University in Wales, co-author of the study published in the journal Scientific Reports.
"I find desert dunes very beautiful," Duller added. "The sight of the sinuous curves, and the way that the light and shadow changes with the sun mean that they always look different, whether that is in the cool of the morning, the midday sun or near sunset. The different colors of sand in different deserts are also very striking, with yellow, white, red and even black dunes in different parts of the world."
The ground-penetrating radar revealed the layers within the Lala Lallia dune, showing how it was constructed over time through accumulating sand and how parts of its internal structure resembled other types of dunes.
"Star dunes are formed in areas with complex wind regimes, which means winds blowing from different directions, and net sand accumulation, points within the desert where big piles of sand can be blown around to form giant dunes," said Birkbeck University of London sedimentologist and study co-author Charlie Bristow.
The researchers also determined that Lala Lallia is moving westerly at a speed of about 1.6 feet (0.5 meters) annually.
While many star dunes are known today, only a single ancient one has been found preserved as sandstone in the geological record, dating to about 250 million years ago, in Scotland. By revealing their internal structure, the researchers said their findings provide a guide for geologists to identify more sandstone remnants of ancient star dunes.
Earth's largest star dunes are found in the Badain Jaran desert in western China. Star dunes also are found in places including the Namib Sand Sea in Namibia, large sand seas in Algeria such as the Grand Erg Oriental and Grand Erg Occidental, and Rub' al Khali in Saudi Arabia. In North America, Great Sand Dunes National Park in Colorado contains a series of them.
"They form extraordinary and awe-inspiring landscapes," Bristow said. "From the ground they can be intimidating, mobile mountains of sand."

Most Viewed

 
 
Varieties

Rain Further Batters Storm-Hit Portugal, Thousands Evacuated

A flooded area in Ceira, Coimbra, Portugal, February 11, 2026. (Reuters)
A flooded area in Ceira, Coimbra, Portugal, February 11, 2026. (Reuters)
TT
TT

Rain Further Batters Storm-Hit Portugal, Thousands Evacuated

A flooded area in Ceira, Coimbra, Portugal, February 11, 2026. (Reuters)
A flooded area in Ceira, Coimbra, Portugal, February 11, 2026. (Reuters)

More ‌heavy rain flooded several rural areas in the north of storm-battered Portugal on Wednesday, leaving levees at risk of bursting around the medieval city of Coimbra and forcing authorities to evacuate about 3,000 residents as a precaution.

A succession of deadly storms has hammered mostly central and southern parts of the country since late January, blowing roofs off houses, flooding several towns and leaving hundreds of thousands without electricity for days. At least 15 people have died as a consequence of the storms, including indirect ‌victims.

As the ‌storms let up this week, a weather ‌phenomenon ⁠known as an "atmospheric river" - ⁠a wide corridor of concentrated water vapor carrying massive amounts of moisture from the tropics - brought new downpours, affecting the north to a greater extent.

RISK OF DAM OVERFLOWING

Municipal authorities in Coimbra ordered the precautionary evacuation late on Tuesday of around 3,000 people most at risk from the River Mondego bursting its banks, ⁠and the operation was still under way on ‌Wednesday, with police making door-to-door checks ‌and bussing residents to shelters.

Regional Civil Protection official Carlos Tavares ‌said on Wednesday the situation could worsen between late Wednesday ‌and midday Thursday, as the rain could cause the Aguieira dam, 35 km northeast of Coimbra, "to overflow, sweep away levees and trigger further flooding".

Part of Coimbra's ancient city wall, on a hillside in one ‌of Europe's oldest university towns and a UNESCO World Heritage site, collapsed, shutting the road below ⁠and forcing ⁠the closure of the municipal market, the city hall said.

Prime Minister Luis Montenegro was due in Coimbra to oversee the emergency response after Interior Minister Maria Lucia Amaral resigned following criticism from opposition parties and local communities over what they described as the authorities' slow and failed response to devastating Storm Kristin two weeks ago.

In central Portugal, just across the River Tagus from Lisbon, authorities evacuated the village of Porto Brandao due to the risk of landslides, and around 30 people were removed from their homes after a landslide in the neighboring beachside area of Caparica.

Varieties

Record Heat and Raging Fires Ring in 2026 Across the Southern Hemisphere 

A helicopter battles a forest fire in the Biobio region, where multiple wildfires have prompted emergency evacuations, in Florida, Chile, January 21, 2026. (Reuters)
A helicopter battles a forest fire in the Biobio region, where multiple wildfires have prompted emergency evacuations, in Florida, Chile, January 21, 2026. (Reuters)
TT
TT

Record Heat and Raging Fires Ring in 2026 Across the Southern Hemisphere 

A helicopter battles a forest fire in the Biobio region, where multiple wildfires have prompted emergency evacuations, in Florida, Chile, January 21, 2026. (Reuters)
A helicopter battles a forest fire in the Biobio region, where multiple wildfires have prompted emergency evacuations, in Florida, Chile, January 21, 2026. (Reuters)

From Argentina to Australia to South Africa, record heat and raging wildfires are rampaging through the Southern Hemisphere at the start of 2026, with scientists predicting that even more extreme temperatures could lie ahead - and possibly another global annual high - after three of the hottest years on record.

In January, a record-setting heat dome enveloped Australia, sending temperatures near 50 degrees C (122 degrees F) while heat and catastrophic wildfires gripped parts of South America, setting remote parts of Argentina's Patagonia ablaze and killing 21 people in coastal towns in Chile. In addition, South Africa has been experiencing its worst wildfires in years.

The extremes are occurring even as the world remains under the cooling influence of a weak La Nina, a climate cycle marked by cooler waters in the central and eastern Pacific that began in December 2024. Despite this moderating factor, temperatures are reaching record highs in various locales.

"This means the effect of human-caused climate change is overwhelming natural variability," said climate scientist Theodore Keeping of Imperial College London and the international research collaboration World Weather Attribution, who specializes in research on wildfires and extreme heat.

"As we transition into a neutral or even El Nino phase, we'll expect the incidence of extreme heat events around the world to be further amplified," Keeping added.

El Nino typically has the opposite effect of La Nina, warming the central and eastern Pacific and boosting global temperatures.

This year is forecast to be about 1.46 degrees C (2.6 degrees F) above pre-industrial levels, which would make it the fourth consecutive year to be higher than 1.4 degrees C (2.5 degrees F) above pre-industrial levels, according to Adam Scaife, head of the long-range prediction at the United Kingdom's national weather ‌and climate service.

The 2015 ‌international climate treaty, known as the Paris Agreement, aimed to keep warming below 1.5 degrees C (2.7 degrees F) above pre-industrial levels.

"If a big ‌El Nino ⁠were to develop ⁠quickly in 2026 then it's still possible 2026 could be a record," Scaife said. The World Meteorological Organization said last month that the past three years were the warmest on record.

FIRE RAGES FROM WOODS TO WATER

While most wildfires are caused by human activity, they are also a natural part of many ecosystems. Persistent heat, drought and extreme temperatures, however, are turning once-manageable fires into increasingly uncontrollable and destructive events.

Many ecosystems are not adapted to such hot, dry conditions, allowing fires to grow larger and more intense, often causing permanent damage, Keeping said.

The fires that burned through Argentina's Los Alerces National Park illustrate the shift, according to meteorologist Carolina Vera of the Center for Ocean and Atmospheric Research at the University of Buenos Aires.

The park, a UNESCO World Heritage site, is home to trees that have lived more than 3,000 years.

Local officials determined that a lightning strike caused the fire. The blaze initially was under control. But Vera said a heat wave and strong winds caused it to spread about 20 km (12 miles) in a single day, making it the worst wildfire there ⁠in two decades.

The region has been drought-stricken since 2008. Temperatures during the first two weeks of January were about 6 degrees C (11 degrees F) above ‌normal.

"These fires used to burn themselves out and form part of the forest's natural dynamics," Vera said.

"This is an example of ‌how climate change can alter a natural fire, because it appeared to be caused by lightning," Vera said.

There are no towns in that remote area.

Fires erupted in the southern part of neighboring Chile later in January and ‌crossed into the greater Concepcion area, the country's third-largest metropolitan region, destroying hundreds of homes and killing 21 people in coastal communities.

Keeping said the blazes mirrored recent disasters in places such as ‌Los Angeles, Athens and the Hawaiian island of Maui.

"Where there's been the greatest loss of life, it almost always comes down to evacuation being difficult or impossible," Keeping said. "That's particularly true in regions affected by strong downslope winds toward the coast."

WHIRLWINDS OF FIRE

About 80% of Punta de Parra, a small coastal town in southern Chile surrounded by hills and forests, was destroyed.

Punta de Parra residents said they had little time to evacuate. Doralisa Silva, 34, said she heard about a fire in a nearby community the night the blaze reached the town.

"Out of nowhere, the forest started burning and all the houses caught fire," Silva said. "The fire was on us in the blink ‌of an eye. There was nothing we could do."

Silva said her family was among the last to try to flee because they had no vehicle. Silva said flames blocked their exit as embers rained down as she and her partner Hermes Barrientos fled with their ⁠2-year-old daughter.

Barrientos said winds of nearly 70 km ⁠per hour (43.5 mph) whipped through the area, creating whirlwinds of fire that spread to the beach and trapped residents. The family and others eventually found refuge in a large dirt field at the center of town, and spent the night watching their community burn.

A FUTURE FILLED WITH FIRES

Record-breaking heat in southeastern Australia has also fueled the country's worst fires since the deadly 2019-2020 season, when 33 people were killed.

In addition, the 2025-2026 fire season has been the most severe in South Africa in a decade, according to officials, killing wildlife and hitting tourist destinations such as Mossel Bay and Franschhoek.

"The hot, dry and windy conditions that drive the most extreme wildfires are becoming more intense and more likely," Keeping said. "And it's happening all around the world."

The Southern Hemisphere has warmed by about 0.15 to 0.17 degrees C (0.27 to 0.30 degrees F) per decade since the 1970s, compared to 0.25 to 0.30 degrees C (0.45 to 0.54 degrees F) in the Northern Hemisphere - largely because its vast oceans absorb heat more slowly and because of Antarctic meltwater.

Still, southern land masses are now warming at similar rates to northern land masses, and contrasts between warming land and cold meltwater can intensify weather patterns, leading to prolonged heat waves, droughts or flooding.

Keeping said adaptation is critical, including authorities managing vegetation near cities and developing effective evacuation plans, and builders using fire-resistant materials. Wildfires are inflicting mounting economic damage. A 2026 report by insurance broker Aon estimated global insured wildfire losses at $42 billion in 2025, up from an average of $4 billion annually between 2000 and 2024. The Los Angeles fires last year were the costliest on record.

Swiss Re, the world's second-largest reinsurer, found that wildfires accounted for about 1% of global insured losses from natural disasters before 2015, but now represent 7%, with economic losses linked to fires rising by about $170 million a year since 1970.

"You actually cannot stop a lot of these really large intense wildfires. They're simply too big," Keeping said.

The most important way forward, Keeping said, is to "have a serious conversation about limiting future climate change to prevent this issue from worsening."

Varieties

Study: Noisy Humans Harm Birds and Affect Breeding Success

FILE - Birdhouses line a path outside a resident's room at the Ida Culver House Ravenna, a senior independent and assisted living home in Seattle, on May 21, 2020. (AP Photo/Elaine Thompson, File)
FILE - Birdhouses line a path outside a resident's room at the Ida Culver House Ravenna, a senior independent and assisted living home in Seattle, on May 21, 2020. (AP Photo/Elaine Thompson, File)
TT
TT

Study: Noisy Humans Harm Birds and Affect Breeding Success

FILE - Birdhouses line a path outside a resident's room at the Ida Culver House Ravenna, a senior independent and assisted living home in Seattle, on May 21, 2020. (AP Photo/Elaine Thompson, File)
FILE - Birdhouses line a path outside a resident's room at the Ida Culver House Ravenna, a senior independent and assisted living home in Seattle, on May 21, 2020. (AP Photo/Elaine Thompson, File)

Noise pollution is affecting bird behavior across the globe, disrupting everything from courtship songs to the ability to find food and avoid predators, a large-scale new analysis showed on Wednesday.

Researchers reviewed nearly four decades of scientific work and found that noises made by humans were interfering with the lives of birds on six continents and having "strong negative effects" on reproduction success.

Previous research on individual species has shown that single sources of anthropogenic noise -- such as planes, traffic and construction -- can affect birds as it does other wildlife.

But for this study, the team performed a wider analysis by pooling data published since 1990 across 160 bird species to see if any broader trends could be established.

The study, published in the journal Proceedings of the Royal Society B, found clear evidence of a "pervasive" impact of noise pollution on birds worldwide.

"We found that noise significantly impacts communication risk behaviors, foraging, aggression and physiology and had a strong effect on habitat use and a negative impact on reproduction," AFP quoted it as saying.

This is because birds rely on acoustic information to survive, making them particularly vulnerable to the modern din produced by cars, machinery and urban life.

"They use song to find mates, calls to warn of predators, and chicks make begging calls to let their parents know they're hungry," Natalie Madden, who led the research while at the University of Michigan, said in a statement.

"So if there's loud noise in the environment, can they still hear signals from their own species?"

In some cases, noise pollution interrupted mating displays, caused males to change their courtship songs, or masked messages between chicks and parents.

The study included many common species such as European robins and starlings, house sparrows, and great tits.

The response varied between species, with birds that nest close to the ground suffering greater reproductive harm, while those using open nests experienced stronger effects on growth.

Birds living in urban areas, meanwhile, tended to have higher levels of stress hormones than those outside of cities.

Some 61 percent of the world's bird species have declining populations, mostly due to habitat loss driven by expanding agriculture and logging, the International Union for Conservation of Nature said in October.

The study authors said that noise pollution was an "underappreciated consequence" of humanity's impact on nature, especially compared to biodiversity loss and climate change.

But some relatively simple fixes could make a big difference for birds, they said.

Madden told AFP that shifting from noisier cars and landscaping tools such as mowers and leaf blowers to electric-powered alternatives was one idea.

Another could be "running machinery outside peak breeding seasons, avoiding activity when birds are migrating through an area, or shifting construction away from habitats that support vulnerable species", she added.

Buildings could also be adapted to muffle sound in the same way they are constructed to improve visibility and minimize bird collisions, said the study's senior author Neil Carter, from the University of Michigan.

"So many of the things we're facing with biodiversity loss just feel inexorable and massive in scale, but we know how to use different materials and how to put things up in different ways to block sound," he said.