GeoLog

GeoLog

Imaggeo on Mondays: Antarctic winds make honeycomb ice

Imaggeo on Mondays: Antarctic winds make honeycomb ice

These delicate ice structures may look like frozen honeycombs from another world, but the crystalline patterns can be found 80 degrees south, in Antarctica, where they are shaped by the white continent’s windy conditions.

In Western Antarctica is a 9-kilometre line of rocky ridges, called Patriot Hills. Often cold wind furiously descends from the hills across Horseshoe Valley glacier, sculpting doily-like designs into the surface layer. “The wind exploits weaknesses in the ice structure, picking out the boundaries between individual ice crystals, leading to the formation of a honeycomb pattern,” said Helen Millman, a PhD student at the University of New South Wales Climate Change Research Centre, who captured this photograph at Patriot Hills.

Besides creating decorations out of Antarctica’s ice, the region’s intense winds, known as katabatic winds, also cause sublimation, in which the ice on the glacier’s surface turns directly into water vapour. This phenomenon creates a snow-free zone that experiences a net loss in frozen mass, also known as ablation; it also gives the ice a slightly blue hue and ”small, smooth waves that resemble the ocean in a light breeze, despite the intensity of the katabatic winds,” Millman added.

A stretch of blue ice in Antarctica. Credit: Helen Millman

“Since older ice rises as the surface layers are ablated, the ice at the surface of blue ice areas may be hundreds of thousands, or even millions of years old,” said Millman. This allows for some pretty interesting geological artifacts to reach the glacier’s surface, such as meteorites. “This conveyor belt of old ice rising to the surface means that high concentrations of meteorites can be found in blue ice areas.” Scientists can study these ancient Antarctic meteorites to learn more about the formation and evolution of our solar system. The Antarctic Search for Meteorites program for instance has collected more than 21,000 meteorites since 1976, and are on the hunt for more.

References

IceCube South Pole Neutrino Obesrvatory, University of Wisconsin-Madison

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/.

An overnight train view of China’s Anthropocene – Part 2

An overnight train view of China’s Anthropocene – Part 2

Science fiction is no match for industrial non-stop China. Electric bikes zip across the cities of Shanghai and Beijing, and soundtrack the neon nights with their passing whirr. Here, some kind of two-wheeled revolution has taken place which are we completely unaware of in the West. It’s Blade Runner meets Total Recall in a future which has already come to pass.

The very existence of our elegant night train from Shanghai to Beijing is itself a reflection of the causes of air pollution and the associated health problems in China. So are the gigantic skyscrapers which hang over Shanghai, the cars and motorbikes which fill its streets, and the factories that crowd the landscape in and around the city.

This is uncapped capitalism, with government officials that often appear reluctant to implement major environmental regulations to safeguard its citizens. According to a 2017 Chinese media report, an assessment of companies in the Beijing area established that more than 70% are violating air pollution regulations.

This is grim news. But what about the environmental movement? Well, it’s growing.

Grass-roots environmental activism has gained ground in China, but has often been confronted with suppression, as police forces have been known to break up protests and detain activists and journalists who speak out against the powers that be. Without these forces at work the people have no voice and industrial actors can continue polluting the lungs of their fellow citizens without major repercussions.

That being said, over the last few years the Chinese government has announced several initiatives to tackle air pollution and other environmental issues in the near future. This includes implementing a carbon trading scheme, establishing a ban on petrol and diesel cars, capping coal-fired power use, to name a few projects. Recently, China has laid out a new Air Pollution Action Plan, requiring many key regions to meet strict air quality targets by 2020.

These projects have potential, as past policies have experienced degrees of success. For example, China’s 2013 Air Pollution Action Plan helped lower the annual average PM2.5 level in Beijing to 58µg/m³ by 2017, a 35% drop in air pollution.

However, at the moment, it remains unclear what the impact of new these plans will be, or if they will be enough to address human health risks. In the case of Beijing, the level of air pollution in the city is still well above the standard set by the World Health Organization, who recommends that the annual average PM2.5 level should be below 10 µg/m³.

Air Pollution in Victoria Harbour in Hong Kong. (Credit: Yym1997, distributed via Wikimedia Commons).

For sure, investment in renewable technologies – itself a way to create employment in research and development – will also help reduce the burning of unsustainable fossil fuels. The electric bikes which surround us as we walk the streets of Shanghai demonstrate progress. Additionally, China has become a leader in renewable energy investment, accounting for 45% of the world’s commitment to renewables in 2017. But there remain problems around emissions from the pharmaceutical and petrochemical industries, themselves major contributors to air pollution in the country.

There have been steps in the right direction, and China has the potential to become a world leader in renewable tech; after all, it is likely that Earth’s next super power will be accelerated, not retarded, by a clean energy revolution. But for now, the smog clouds remain, and for me they serve to warn that governments and corporations worldwide are taking control over nature. The consequences will not be pleasant.

This is Part 2 of a two-part series on the impact of air pollution in China and the country’s steps taken to user a clean era for the 21st century. You can read Part 1 via Geolog.

By Conor Purcell, a Science & Nature Writer with a PhD in Earth Science

Conor Purcell is a science journalist with a PhD in Earth Science. He is the founding editor of www.wideorbits.com and can be found on twitter @ConorPPurcell and some of his other articles at cppurcell.tumblr.com.

Editor’s note: This is a guest blog post that expresses the opinion of its author, whose views may differ from those of the European Geosciences Union. We hope the post can serve to generate discussion and a civilised debate amongst our readers.

 

Imaggeo on Mondays: Fairy chimneys in Love Valley

Imaggeo on Mondays: Fairy chimneys in Love Valley

Every year tourists from around the world flock to Love Valley in Göreme National Park in the Cappadocia region of central Turkey to marvel at the region’s peculiarly pointy geological features. These cone-shaped formations, known as ‘fairy chimneys’ or hoodoos, dominate the park’s skyline, with some rocky spires extending up to 40 metres towards the sky.

While the name ‘fairy chimney’ suggests mythical origins, these rocks began to take shape millions of years ago, when many active volcanoes dominated the region. “The deposits of [volcanic] ash, lava and basalt laid the foundations for today’s landscape,’ commented Alessandro Demarchi in the photo’s description, who captured the stunning photograph featured today. The volcanic material consolidated into a soft rock known as ‘tuff.’ Then over the years, natural weathering forces like wind and water eroded weaker parts of the rock away, leaving behind the pinnacles we see now.

Around the 4th century, during the reign of the Roman empire, many Christian pilgrims traveled to Cappodocia to flee persecution. They built their new life into the region’s rocks, carving out a network of homes and churches from the towers of tuff. If you look closely at background of the image, you can even spot remnants of their handiwork.

The region was named a UNESCO World Heritage Site in 1985, and today you can enjoy the extraordinary geological formations, as well as their cultural history, either from the ground or up in the air through hot air balloon tours.

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/.

GeoTalk: To understand how ice sheets flow, look at the bedrock below

GeoTalk: To understand how ice sheets flow, look at the bedrock below

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Mathieu Morlighem, an associate professor of Earth System Science at the University of California, Irvine who uses models to better understand ongoing changes in the Cryosphere. At the General Assembly he was the recipient of a 2018 Arne Richter Award for Outstanding Early Career Scientists.  

Could you start by introducing yourself and telling us a little more about your career path so far?

Mathieu Morlighem (Credit: Mathieu Morlighem)

I am an associate professor at the University of California Irvine (UCI), in the department of Earth System Science. My current research focuses on better understanding and explaining ongoing changes in Greenland and Antarctica using numerical modelling.

I actually started glaciology by accident… I was trained as an engineer, at Ecole Centrale Paris in France, and was interested in aeronautics and space research. I contacted someone at the NASA Jet Propulsion Laboratory (JPL) in the US to do a six-month internship at the end of my master’s degree, thinking that I would be designing spacecrafts. This person was actually a famous glaciologist (Eric Rignot), which I did not know. He explained that I was knocking on the wrong door, but that he was looking for students to build a new generation ice sheet model. I decided to accept this offer and worked on developing a new ice sheet model (ISSM) from scratch.

Even though this was not what I was anticipating as a career path, I truly loved this experience. My initial six-month internship became a PhD, and I then moved to UCI as a project scientist, before getting a faculty position two years later. Looking back, I feel incredibly lucky to have seized that opportunity. I came to the right place, at the right time, surrounded by wonderful people.

This year you received an Arne Richter Award for Outstanding Early Career Scientists for your innovative research in ice-sheet modelling. Could you give us a quick summary of your work in this area?

The Earth’s ice sheets are losing mass at an increasing rate, causing sea levels to rise, and we still don’t know how quickly they could change over the coming centuries. It is a big uncertainty in sea level rise projections and the only way to reduce this uncertainty is to improve ice flow models, which would help policy makers in terms of coastal planning or choosing mitigation strategies.

I am interested in understanding the interactions of ice and climate by combining state-of-the-art numerical modelling with data collected by satellite and airplanes (remote sensing) or directly on-site (in situ).  Modelling ice sheet flow at the scale of Greenland and Antarctica remains scientifically and technically challenging. Important processes are still poorly understood or missing in models so we have a lot to do.

I have been developing the UCI/JPL Ice Sheet System Model, a new generation, open source, high-resolution, higher-order physics ice sheet model with two colleagues at the Jet Propulsion Laboratory over the past 10 years. I am still actively developing ISSM and it is the primary tool of my research.

More specifically, I am working on improving our understanding of ice sheet dynamics and the interactions between the ice and the other components of the Earth system, as well as improving current data assimilation capability to correctly initialize ice sheet models and capture current trends. My work also involves improving our knowledge of the topography of Greenland and Antarctica’s bedrock (through the development of new algorithms and datasets). Knowing the shape of the ground beneath the two ice sheets is key for understanding how an ice sheet’s grounding line (the point where floating ice meets bedrock) changes and how quickly chunks of ice will break from the sheet, also known as calving.

Steensby Glacier flows around a sharp bend in a deep canyon. (Credit: NASA/ Michael Studinger)

At the General Assembly, you presented a new, comprehensive map of Greenland’s bedrock topography beneath its ice and the surrounding ocean’s depths. What is the importance of this kind of information for scientists?

I ended up working on developing this new map because we could not make any reliable simulations with the bedrock maps that were available a few years ago: they were missing key features, such as deep fjords that extend 10s of km under the ice sheet, ridges that stabilize the retreat, underwater sills (that act as sea floor barriers) that may block warm ocean waters at depth from interacting with the ice, etc.

Subglacial bed topography is probably the most important input parameter in an ice sheet model and remains challenging to measure. The bed controls the flow of ice and its discharge into the ocean through a set of narrow valleys occupied by outlet glaciers. I am hoping that the new product that I developed, called BedMachine, will help reduce the uncertainty in numerical models, and help explain current trends.

3D view of the bed topography and ocean bathymetry of the Greenland Ice Sheet from BedMachine v3 (Credit: Peter Fretwell, BAS)

How did you and your colleagues create this map, and how does it compare to previous models?

The key ingredient in this map, is that a lot of it is based on physics instead of a simple “blind” interpolation. Bedrock elevation is measured by airborne radars, which send electromagnetic pulses into the Earth’s immediate sub-surface and collect information on how this energy is reflected back. By analyzing the echo of the electromagnetic wave, we can determine the ice thickness along the radar’s flight lines. Unfortunately, we cannot determine the topography away from these lines and the bed needs to be interpolated between these flight lines in order to provide complete maps.

During my PhD, I developed a new method to infer the bed topography beneath the ice sheets at high resolution based on the conservation of mass and optimization algorithms. Instead of relying solely on bedrock measurements, I combine them with data on ice flow speed that we get from satellite observations, how much snow falls onto the ice sheet and how much melts, as well as how quickly the ice is thinning or thickening. I then use the principle of conservation of mass to map the bed between flight lines. This method is not free of error, of course! But it does capture features that could not be detected with other existing mapping techniques.

3D view of the ocean bathymetry and ice sheet speed (yellow/red) of Greenland’s Northwest coast (Credit: Mathieu Morlighem, UCI)

What are some of the largest discoveries that have been made with this model? 

Looking at the bed topography alone, we found that many fjords beneath the ice, all around Greenland, extend for 10s and 100s of kilometers in some cases and remain below sea level. Scientists had previously thought some years ago that the glaciers would not have to retreat much to reach higher ground, subsequently avoiding additional ice melt from exposure to warmer ocean currents. However, with this new description of the bed under the ice sheet, we see that this is not true. Many glaciers will not detach from the ocean any time soon, and so the ice sheet is more vulnerable to ice melt than we thought.

More recently, a team of geologists in Denmark discovered a meteorite impact crater hidden underneath the ice sheet! I initially thought that it was an artifact of the map, but it is actually a very real feature.

More importantly maybe, this map has been developed by an ice sheet modeller, for ice sheet modellers, in order to improve the reliability of numerical simulations. There are still many places where it has to be improved, but the models are now really starting to look promising: we not only understand the variability in changes in ice dynamics and retreat all around the ice sheet thanks to this map, we are now able to model it! We still have a long way to go, but it is an exciting time to be in this field.

Interview by Olivia Trani, EGU Communications Officer