GeoLog

Imaggeo

Imaggeo on Mondays: Sand and snow on the Tibetan Plateau

Imaggeo on Mondays: Sand and snow on the Tibetan Plateau

Roughly 50 million years ago, the Eurasian and Indian continental plates began to crash into each other, dramatically changing the landscape of modern-day Asia. The force of the collision caused the Earth to scrunch together at the zone of impact, subsequently forming the Himalayan mountain range. However, to the north of the crash, a stretch of the Earth uplifted without bunching up or wrinkling; instead the clash formed an elevated flat surface five times as large as France, now known as the Tibetan Plateau.

The Tibetan Plateau is often called the ‘Roof of the World,’ as the region’s average elevation exceeds 4,500 metres and is home to the Earth’s highest peaks, including Mount Everest and K2. The plateau is also a crossroad for many different kinds of ecosystems and geologic features, including deep canyons, winding rivers, massive glaciers, boundless grasslands and alpine deserts.

This week’s featured image, taken by Monica Cardarilli, a risk and safety engineer at the Sapienza University of Rome in Italy, gives a snapshot into the plateau’s dynamic and diverse environment, where snow, water, soil and organic matter all make their mark on the landscape. “In this picture natural elements are expressed by the colors, like a painting where the whole exceeds the single parts in a mix of perceptions,” says Cardarilli.

The landscape of the plateau and the surrounding mountainous regions is also as fragile as it is diverse, and many scientists fear that climate change and other human activities are rapidly altering this corner of the Earth. For example, research suggests that the Tibetan Plateau is experiencing higher rates of warming compared to the global average, which has already caused concerning levels of glacier melt, flooding, desertification and grassland degradation in the area.

A recent report suggests that, due to climate change, at least one third of the glaciers situated within the plateau and the surrounding Hindu Kush-Himalaya (HKH) region will be lost from ice melt by the end of the century. This level of melting would have major consequences for the surrounding population, as more than 1.5 billion people rely on freshwater that stems from the region and many local communities would be threatened by severe flooding and lake bursts.

The report, undertaken by more than 200 researchers, warns that climate action is necessary to prevent even further melting in this region and avoid worse disasters.

By Olivia Trani, EGU Communications Officer

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: A painted forest fire

Imaggeo on Mondays: A painted forest fire

This week’s featured image may appear to be a painted landscape, but the picture is in fact a photo, taken ten years ago by Victoria Arcenegui, an associate professor at Miguel Hernández University in Spain, during a controlled forest fire in northern Portugal.

The blaze is actually hot enough to distort the image, making some of the flames appear as brush strokes, beautifully blurring together the colours of the fire, trees and smoke.

Intense heat such as this influences how light travels to both the human eye and a camera lens. As air warms it expands, while colder air becomes denser. As a result, light travels quicker through thinner warm air but is refracted more in denser cool air. So when there are shifting pockets of cold and hot air, the speed of light through air is constantly changing, creating a shimmering effect.

The prescribed fire in this photo is not only showcasing an interesting phenomenon, but is also providing an important service to the region’s ecosystem. For decades, forest fires were often considered detrimental to the environment, however, researchers say that small natural fires help strengthen ecosystems. For example, by burning old dead vegetation, these fires cycle nutrients back to the soil and clear space for new plants to grow. In addition, some plant rely on fires to spread or activate seeds. Historically, many wildlife management programmes prevented smaller fires from removing vegetation, subsequently creating overgrown forests, which are more susceptible to larger, more destructive fires.

Now, many researchers are studying the effectiveness of prescribed burning, where forests are periodically set on fire in a controlled setting to replicate the ecological impact of natural fires and reduce wildfire risk.

By Olivia Trani, EGU Communications Officer

References

Santín, C. and Doerr, S. H.: Fire effects on soils: the human dimension, Philosophical Transactions of the Royal Society B: Biological Sciences, 371(1696), 20150171, doi:10.1098/rstb.2015.0171, 2016.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Dust devil sighting in the Atacama Desert

Imaggeo on Mondays: Dust devil sighting in the Atacama Desert

Dust devils are like miniature tornadoes, they form when a pocket of hot air near the surface moves fast upward and meets cooler air above it. As the air rapidly rises, the column of hot air is stretched vertically, thereby moving mass closer to the axis of rotation, which causes intensification of the spinning effect by conservation of angular momentum. In the Atacama Desert [in Chile] they are really common, and the desert is a perfect “lab” to observe and study their formation!

Description by Rita Nogherotto, as it first appeared on imaggeo.egu.eu.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Indonesian mangroves and tsunamis

Imaggeo on Mondays: Indonesian mangroves and tsunamis

Pictured here is a solitary mangrove tree, rooted off the northern coast of the Indonesian island Flores. While this tree has the shallow sandy reef to itself, mangroves are often found clumped together in large forests covering tropical and subtropical coastlines. The propped-up roots of mangrove trees often tangle together, creating a dense natural barrier that can weaken the coastal impact of ocean tides, currents and storms. As a consequence, islands with mangrove forests on their coastlines experience less erosion and less damage from storm surges compared to barer shorelines.

Mangroves are also often said to provide protection against tsunami destruction. Indeed, there have been several cases in which mangroves trees were believed to have curtailed the devastating effect of tsunami waves. Recent research suggests that extensive mangrove forests hundreds of metres wide have been able to reduce tsunami wave heights by 5-30 percent.

Unfortunately, over the past decades, these environmental benefits are now under threat due to deforestation. About half of the global mangrove population (32 million hectares) has been wiped out, often to make way for fish farming operations. In Indonesia, mangrove ecosystem decline has been largely attributed to developing shrimp ponds and logging activities. There are now a number of places where mangrove plantations are supported by local individuals and governments.

Jörn Behrens, a professor of numerical methods in Earth sciences at the University of Hamburg in Germany, captured this shot while on a field trip in Indonesia. He and his colleagues were looking for traces of the powerful 1992 tsunami that struck the coast of the Indonesia island of Flores and other nearby smaller islands.

The tsunami, triggered by a magnitude 7.9 earthquake, sent waves reaching 4 to 27-metres high on the island’s northeastern coast, even destroying a whole village situated on the nearby island Babi. About 2,500 residents and tourists died from the event, with hundreds more injured, and thousands more homeless.

The 1992 Flores tsunami was also one of the first such events documented by an international survey that adhered to internationally accepted post-tsunami assessment standards.  On their field trip Behrens and his colleagues revisited some of sites assessed by the 1992 post-tsunami survey, spoke to eye witnesses, learned about the region’s current mitigation measures, and exchanged latest results from modeling and experimental tsunami research.

While on this field trip, Behrens came across this solitary mangrove, surrounded by what appears to be young mangrove propagules growing out from the water.

By Olivia Trani, EGU Communications Officer

References

Spalding M, McIvor A, Tonneijck FH, Tol S and van Eijk P (2014) Mangroves for coastal defence. Guidelines for coastal managers & policy makers. Wetlands International and The Nature Conservancy.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.