Tag Archives: Landscape

Splendid animation shows the Earth without water — it’s stunning

What would the Earth look like without its oceans? Surprisingly mountainous, a new animation reveals.

Image credits James O’Donoghue via Youtube.

The clip was produced by planetary scientist James O’Donoghue, formerly at NASA and currently working for the Japanese space agency (JAXA). O’Donoghue worked from a video created by NASA physicist and animator Horace Mitchell back in 2008, editing its timing and adding in a tracker to showcase how much water was drained throughout the animation.

All in all, the video is a great way to showcase Earth’s underwater mountain ranges — the longest ones in the world — and the now-submerged paths that took humanity across the continents.

Sans water

“I slowed down the start since, rather surprisingly, there’s a lot of undersea landscape instantly revealed in the first tens of meters,” O’Donoghue told Business Insider.

The landscapes O’Donoghue mentions here are the continental shelves and undersea edges of each continent. These are swathes of land with higher average altitudes than the rest of the ocean floor which surround the continents — they represent the transitional landscape between dry land and the deep abyss.

The land bridges that early humans used to migrate from continent to continent are part of these raised areas. They’re submerged right now but tens of thousands of years ago, when ocean levels were much lower due to an ice age that created huge volumes of ice at the poles, they were raised enough to walk across. In those days, you could just walk from Europe to the UK, to Alaska from Siberia, or from Australia to the many islands surrounding the land down under.

“Each of these links enabled humans to migrate, and when the ice age ended, the water sort of sealed them in,” O’Donoghue adds.

But the oceans are hiding more than the movements of our ancestors. Earth’s longest chains of mountains appear in the video once sea levels have dropped by 2,000 to 3,000 meters. These sunken mountains are known as mid-ocean ridges, and form in the areas where tectonic plates butt heads. Earth’s deepest areas also make an appearance — once all the water is taken away, understandably. These deep-ocean trenches form where tectonic plates move away from one another, creating deep gorges where magma pushes up from the Earth’s interior to generate fresh crust. To give you an idea of just how deep these gorges are, the Mariana Trench first pops up after 6,000 meters of water are removed in the video; however, its bottom only becomes visible after another 5,000-or-so meters.

“I like how this animation reveals that the ocean floor is just as variable and interesting in its geology as the continents,” O’Donoghue concludes.

Around two-thirds of the planet is covered by water. Since we don’t really have many opportunities to see the ocean floor, it is commonly imagined as a vast, flat, featureless expanse. But O’Donoghue’s work showcases the richness of underwater landscapes, and reminds us that the bottom of the ocean isn’t a boring place — it’s one of the most spectacular and untouched frontiers left on Earth.

Cut down half the forest and the rest quickly follows suit

Researchers at the University of Cincinnati (UoC) report finding a ‘tipping point’ for deforestation past which rapid forest loss occurs.

Landscapes are constantly in flux due to natural processes and human activity. The latter can either cause changes directly, think clear-cutting, or indirectly, such as climate change.

Image via Pixabay.

In order to better understand how landscapes react to direct causes of human-driven change, a team at the UoC tracked deforestation dynamics across the planet between 1992 and 2015. They found that, at least on a 9-kilometer-wide scale, deforestation occurs slowly until about half of the forest is gone — then the remaining trees disappear quickly. Mixed landscapes such as a forest together with agriculture are comparatively few, the authors explain, and tend to homogenize relatively quickly.

The findings provide new insight into landscape change dynamics, and the team hopes they will be used to guide conservation efforts in the future.

Don’t half-forest it

“I think it’s very intuitive. It corresponds to the different climatic zones,” says Professor Tomasz Stepinski, the paper’s corresponding author. “The Earth before people was certainly like that. You had forests and mountains and wetlands and deserts.”

“You would expect people would create more fragmentation, but as it turns out, people never stop. They convert the entire block on a large scale.”

In his previous research, Stepinski investigated the scale of landscape change, showing that around 22% of the Earth’s surface was measurably altered between 1992 and 2015. The single largest transition he found was from woodlands to agricultural fields. The same dataset was used for this study, which aimed to understand the dynamics of how one landscape changes into another. To this end, the team divided up the Earth’s landmasses into (roughly 1.8 million) 81-square-kilometer blocks. These blocks corresponded to 64 different combinations of landscape types.

All in all, the researchers report, some 15% of these blocks transitioned from predominantly one type to predominantly another between 1992 and 2015. Deforestation was the leading cause of man-made landscape change, they add.

Land-use map shows changing landscapes in North and South America between 1992 and 2015. White indicates little or no change. Darker shades indicate the highest rate of change in each category.
Image credits Tomasz Stepinski/UC.

Next, it was time to get to the meat of the matter. Using a class of modeling algorithms known as the Monte Carlo (MC) methods, they looked at how likely different types of landscape changes are to occur over longer periods of time (centuries, in this case).

“The data we have covers 23 years. That’s a relatively short period of time. But from that we can calculate change in the future,” Stepinski said.

Landscapes, they found, tend to shift from one homogenous state to another. In other words, they tend to move towards (predominantly) the same state across all their surface, at least on the 81-sq-km scale the team used. The authors didn’t look into why they behave like this, but Stepinski says it’s likely that as human developments are introduced into an area — such as the construction of logging roads and drainage systems — subsequent change of the landscape becomes easier and happens faster.

“Planet Earth wants to be homogeneous. The land wants to be the same in all these patches. And when they start to change, they don’t stop until they convert everything into another homogeneous block,” he explains.

“I can only speculate [why] because that was not part of the study, but I would imagine two things are happening. If you are cutting forest, you have the infrastructure to finish it. It’s so much easier to cut the rest. Second, the forest is more vulnerable to change when there has been a disturbance.”

The findings largely align with what we know of landscape conservation so far. Wildlife managers will try to preserve larger intact blocks of a certain habitat or landscape as this improves their resilience to virtually every pressure, including climate change and invasive species. Large swathes of wildland are also difficult and expensive to exploit, reducing their attractiveness as sources of raw material or land. Small parcels are just easier to transform, for nature and humans both.

“I think it is interesting that this property applies both to natural and human landscapes,” said co-author Nowosad, a former UC postdoctoral researcher who now works as an assistant professor at the Adam Mickiewicz University in Poland. “This model can be used to help understand how landscapes evolved and are going to evolve in the future,” Nowosad said.

“It’s thought-provoking. My hope is that people will criticize it and come up with different ideas,” Stepinski adds.

The study helps us better understand long-term landscape change, Nowosad explains, adding that it would be interesting to see if the dynamic applies to other types of transitions since the study focused on shifts between forest and agricultural land.

The paper “Stochastic, Empirically Informed Model of Landscape Dynamics and Its Application to Deforestation Scenarios” has been published in the journal Geophysical Research Letters.

Working landscape.

Working landscapes can be used for species conservation alongside economic activities

Privately-owned land in the forests of Costa Rica can help support the same number of vulnerable bird species as the nature reserves they border, according to a new study from the University of California, Davis.

Working landscape.

Working landscape in Vietnam.
Image credits Quang Nguyen Vinh.

Collaborating with local landowners to conserve or restore forests in the working landscapes of Costa Rica can help protect local wildlife, the study reports. Working landscapes are cohesive units of land that are ecologically, socially, and economically connected. Rural areas, which often are dominated by intensive or extensive agricultural, forestry, or other natural resources based economies, are generally a part of a working landscape. In Costa Rica, working landscapes include forest patches, crops, pastures, and small towns. Private lands in regions that are wetter and already have a degree of natural forest cover would help local bird species the most, it adds.

Can’t see the forest for the patches

“With sufficient forest cover, working landscapes — even if degraded and fragmented — can maintain bird communities that are indistinguishable from those found in protected areas,” said lead author Daniel Karp, an assistant professor in the UC Davis Department of Wildlife, Fish and Conservation Biology.

“This means that private landowners have great power to improve the conservation value of their lands through reforestation.”

As part of a larger project funded by National Geographic, the team looked at the state of Neotropical birds at 150 sites across Costa Rica’s northwest over a two-year period.

Agricultural lands in the area host diverse bird communities, the team reports, but not the same species that live in protected areas. These field-dwelling species also had large distributions, meaning they are of lower conservation value (‘not-as-threatened’) as the species in protected areas.

Interestingly, the privately-owned patches of forest in the studied area stood out quite sharply from their surrounding fields. Despite their advanced state of degradation — these plots of forest were degraded by logging, hunting, and fires — they housed the same species of birds as the protected areas. The patches were also better at supporting bird populations in wetter and more forested areas. The team estimates that reforesting the wettest sites would increase bird similarity to protected areas four-fold compared to a two-fold increase in the driest sites.

In a related study, Karp showed that the amount of local forest within about 150 feet of a site was the biggest determinant of the species of birds found there.

“Tropical birds respond very strongly to the amount of forest in their immediate vicinity,” Karp said. “That’s encouraging because it means forest restoration on a small scale, even in small patches, can be really effective in safeguarding vulnerable bird species.”

Costa Rica has experienced decades of forest decline, which prompted the state to offer monetary incentives for landowners who maintained forest on their private lands in the early 1990s. That’s how these patches of forest the study focuses on came to be.

The paper “Remnant forest in Costa Rican working landscapes fosters bird communities that are indistinguishable from protected areas” has been published in the journal Journal of Applied Ecology.

Gullies Mars.

Boiling water shapes Mars’ landscape, experiment reveals

Researchers at The Open University (OU) could finally put the mystery regarding the formation of Mars’ land features to rest. The red planet’s landscapes, they report, is formed by small amounts of water boiling in the thin atmosphere.

Gullies Mars.

Gullies on Mars’ surface are likely formed through this process.
Image credits NASA / Mars Reconnaissance Orbiter.

There’s a good reason why Mars doesn’t make it very high on the ‘best spots for watersports’ lists for — it’s quite dry. There are no oceans, no rivers, no lakes here. There’s also the issue of its whispy-thin but the decidedly deadly atmosphere.

This dryness has also puzzled researchers trying to understand the planet’s landscapes for a long time now. On Earth, water has a central role to play in shaping landscapes. It provides sediment mobility (i.e. it moves particles of soil and rocks around), chisels and polishes through erosion, and adds the final details through chemical alteration. Mars, however, showcases some breathtaking features despite its relative absence of water. The mystery only compounds when you factor in its atmosphere, which is far less able than Earth’s to influence landscapes.

Make do

To get to the bottom of things, a group of scientists from the OU used the university’s Mars Simulation Chamber to re-create conditions on Mars and see how they influence land feature formation. Their work revealed that because of our neighbor’s thin atmosphere (about 0.7% as thick as Earth’s, at roughly 7 mbar) water will spontaneously, and violently, boil on its surface. During periods when Mars’ surface is relatively warm, even a small quantity of water flowing to the surface can move large amounts of sand or other sediments. The team describes the process as material or pellets of material “levitating” on the cushion of vapor released by boiling waters.

Compared to what we’re used to seeing on Earth, even small amounts of liquid water running across Mars’ surface could thus form the large dune flows, gullies, and other characteristic features. Here you can see the difference in sediment flow on the simulated Martian surface during a “cold” (no boil) and “warm” (boil) run. These runs would correspond to mean temperatures on Mars’ surface during cold seasons and warmer ones (i.e. Martian summer.)

Mars leviflow.

Image, map, and elevation data recorded at the end of experiments.
A, d, photographs of the “cold” and “warm” experiments respectively.
D, e, hillshaded relief digital elevation models (DEM) overlain by process-zone maps giving the spatial extent of the different transport types (blue = overland flow, green = percolation, red = pellets, yellow = dry avalanches/saltation) for “cold” (b) and “warm” (e) experiments.
C, F, elevation differences between the start and end of the experiment for “cold” and “warm” runs respectively.
Flow direction is from top to bottom and the same scale is used for all images.
Image credits Jan Raack et al., 2018, N.Comm.

“Whilst planetary scientists already know that the surface of Mars has ‘mass-wasting’ features — such as dune flows, gullies, and recurring slope lineae — which occur as a result of sediment transportation down a slope, the debate about what is forming them continues,” according to Dr Jan Raack, Marie Skłodowska-Curie Research Fellow at The Open University and lead author of the paper.

“Our research has discovered that this levitation effect caused by boiling water under low pressure enables the rapid transport of sand and sediment across the surface. This is a new geological phenomenon, which doesn’t happen on Earth, and could be vital to understanding similar processes on other planetary surfaces.”

The team reports that levitation processes can increase sediment transport nine-fold (as compared to ‘cold’ runs with no boiling and ‘warm’ runs), reducing the amount of water needed to move a given volume of material “by nearly an order of magnitude.” Finally, they calculate that Mars’ reduced gravitational pull would allow these processes to persist up to 48 times longer. While the team admits that this number “is likely to be an overestimation,” even a 10-times longer persistence of the levitation processes “would result in a decameter-extent of sediment disturbance, which should be visible in remote sensing images”. The sediment pellets themselves would likely not be visible in remote-sensing images.

Overall, the team says that levitation processes associated with small water flows on Mars’ surface features have been “widely underestimated”, and call for more observational studies on the matter.

“We need to carry out more research into how water levitates on Mars, and missions such as the ESA ExoMars 2020 Rover will provide vital insight to help us better understand our closest neighbour.”

Sediment transport where this mechanism is active is about nine times greater than without this effect, reducing the amount of water required to transport comparable sediment volumes by nearly an order of magnitude. Our calculations show that the effect of levitation could persist up to ~48 times longer under reduced Martian gravity.

The paper “Water induced sediment levitation enhances downslope transport on Mars” has been published in the journal Nature Communications.