Scientists solve the mystery of honeycomb patterns in salt deserts

Scientists have solved the mystery of the mysterious "honeycomb" patterns found in salt deserts around the world.

These places are among the most extreme and inhospitable places on Earth, and their strangely shaped polygonal structures attract hundreds of thousands of tourists each year.

Salt deserts can be found in areas such as the Badwater Basin in Death Valley, California, and the Salar de Uyuni in Chile.

The new study suggests that the shape and size of the "honeycomb" pattern is caused by the movement of salt water (with a high concentration of dissolved salt) in the soil below the surface.

Scientists at Nottingham Trent University and Graz University of Technology in Austria explain that the fixed size of the features and the speed at which the patterns grow can also be attributed to this.

It was previously believed that the crust of salt in the desert dries up and forms cracks around which "honeycomb" patterns grow.

Other scientists have also hypothesized that the salt crust is constantly growing and bending due to lack of space, forming fuzzy patterns.

However, neither theory explains the fixed size of the "honeycomb" shape, which always ranges between one and two metres. Dr Lucas Göring, Assistant Professor in the Nottingham Trent University School of Science and Technology, said: “In salt deserts, the first thing you see, and almost the only thing you see, is an endless jumble of ordered hexagons and other shapes. The surface patterns reflect the slow upturning of the salty water. "In the soil, a phenomenon a bit like convection cells forming in a thin layer of boiling water. Despite its beauty, winds blowing over salt deserts are a major source of atmospheric dust, and our results will help understand such processes in desert environments." .

The scientists conducted laboratory experiments to see how salt water moved in the sandy soil and analyzed the patterns under different conditions.

And in two field studies in California, scientists observed patterns in nature and collected samples to show that currents in Earth's interior mirror patterns seen at the surface.

The salt deserts in which these patterns occur are not dry and the highly saline groundwater often reaches and lies directly beneath the salt crust.

While this water could be quickly accessed by digging by hand, it would be too salty to drink.

When this brine evaporates in the hot summer sun, the salt remains, making the ground water directly below the surface saltier and therefore heavier than the fresh water that remains lurking below.

If this difference in salinity is high enough, salt water near the surface begins to sink down, while fresh water rises from below.

The study suggests that as convective rolls develop next to each other in the Earth, they are compressed together and produce hexagonal "honeycomb" patterns along their edges that sink brine.

And when there is a particularly high percentage of salt, the salt also crystallizes on the surface. Over time, the resulting crust forms raised humps and edges that create a "honeycomb" pattern.

The study, which involved the Max Planck Institute for Dynamics and Self-Organization, the University of Southampton, the University of Leeds, the University of Götting and the University of Oxford, is published in Physical Review X.

Source: The Independent

A study warns of the collapse of the ice sheet in both poles sooner than expected!

A new study warns that the ice sheets in Greenland and Antarctica are heading towards irreversible melting even if we manage to stabilize global temperatures by peaking at 2 degrees Celsius.

"If we miss this emission target, the ice sheets will break up and melt at an accelerated rate, according to our calculations," explains climate physicist Axel Timmermann of the Institute of Basic Sciences in Korea.

So far, the world's sea level has risen by about 20 cm on average over the past century. UN Secretary-General António Guterres told Security Council discussions in New York that the calculated acceleration would put one in ten people at immediate risk from sea level rise.

"For the hundreds of millions of people who live in small island developing states and other low-lying coastal areas around the world, sea level rise presents an avalanche of problems. We will see mass migration," he said.

By including feedback mechanisms that were missing from previous modeling, Pusan ​​National University climate scientist Jun-Young Park and his colleagues expect the major tipping point to approach faster than expected.

"Computer models that simulate the dynamics of ice sheets in Greenland and Antarctica often do not take into account the fact that melting of an ice sheet will affect ocean processes that, in turn, can feed back into the ice sheet," Park explains. 

As ice on land and sea continues to melt at an ever-increasing rate, meltwater flowing into the ocean is concentrated at the surface, reducing heat exchange from the depths and further warming the Earth's interior. This extra heat is eroding the frozen buttresses that prevent ice drift in Antarctica, causing more meltwater to flow into the ocean.

The team notes that we are already seeing some of these effects in real time, with previously unheard of events such as rain in Greenland and marked increases in meltwater variability on the Antarctic ice shelf.

But Park and his team's new calculations indicate that this process is irreversible and can begin at just 1.8 degrees Celsius.

Only in mitigation scenarios, keeping temperatures below 1.5°C, could the model have avoided such a rapid acceleration of sea level rise.

"If we don't take action, the retreat of the ice sheets will continue to increase sea levels by at least 100 cm over the next 130 years. This will be on top of other contributions such as the thermal expansion of ocean waters," Timmermann explains.

Such a scenario would seriously affect megacities on every continent, including metropolitan centers such as Cairo, Mumbai, Shanghai, London, Los Angeles, New York and Buenos Aires.

Although the possibility may be alarming, there are plenty of features affecting our complex ecosystems that the new modeling hasn't captured, such as the effects of narrow coastal currents.

Atmospheric scientist Robin Smith, who was not involved in the study, explains: “It is critical that improvements be made to the latest climate models. Although more work is needed to mitigate uncertainties in such projections, this study clearly demonstrates the importance of taking Rapid action to reduce anthropogenic greenhouse gas emissions as quickly as possible to reduce the risks associated with the loss of major ice sheets." 

This does not mean that we have the luxury of waiting to find out the answer. Every increase in warming that we can avoid will give us a much better chance of helping future societies avoid the worst of a rapidly warming planet.

This research has been published in the journal Nature Communications.

Source: ScienceAlert