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Imaggeo on Mondays: Cordillera del Paine

9 Jul

Cordillera del Paine by Martin Mergili, distributed by EGU under a Creative Commons licence.

Images such as the one above inspire scientists and nature lovers alike. This photograph, showing a Chilean landscape with elements representative of various Earth-science disciplines, is simply stunning. In a beautiful mix of shapes and colours, a quiet lake with floating icebergs appears tucked in between a roughed mountain in the background and a colourful double rainbow in the foreground.

The photographer, Martin Mergili of the University of Natural Resources and Life Sciences in Vienna, captured this inspiring scenery during a holiday trip a few years ago. The photo shows the eastern edge of the southern part of Cordillera del Paine, a “small but spectacular” mountain group in the Torres del Paine National Park, which is located in Chilean Patagonia almost 2,000 kilometres south of Santiago de Chile.

“The prominent peaks visible in the left portion of the image are the Cuernos del Paine,” Martin explains. “The rainbow in the foreground is not just decoration, it reflects the ever-changing weather patterns characteristic of that area. Even though it is located in the rainshade of the Cordillera at the edge of the semi-arid Patagonian lowlands, the westerlies bring a lot of moist air from the Pacific Ocean. The icebergs in the lake in the foreground (Lago Grey) originate from the large Glaciar Grey calving into the lake.”

More stunning images of this and other landscapes are available from Martin’s website.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Geosciences column: For permafrost, (sediment) size does matter

4 Jul

In this month’s Geosciences Column, David Bressan – now a regular EGU contributor – highlights a recent result published in The Cryosphere with implications on the occurrence and preservation of alpine permafrost.

The last 150 years saw an increase of 0.8°C in the Earth’s mean global temperature. In mountain ranges like the European Alps, however, this rising trend is even more pronounced with an increase of 1.5°C in temperature observed over the same period. This rise not only accelerates the retreat of the alpine glaciers, but also causes the slow degradation of alpine permafrost – solid material with temperatures well below the freezing point of water at 0°C – and rock glaciers – lobes composed of a mixture of ice and rock debris, covered by a few meters of ice-free debris.

On a superficial glimpse, the permafrost seems relatively well isolated from superficial changes due to the cover of ice-free soil and rocks. However, measurements in the past few years have shown that the melting rate of ice inside the rock glaciers significantly increased in the last decades, which could lead to the destabilization of mountain slopes and could influence the hydrology of nearby springs.

To understand the behavior of permafrost in a warmer future it is therefore essential to understand how the material (for example different rock types) and the texture (like grain size or distribution) of the layers covering the permafrost transport heat from the warming surface into the frozen underground. Heat transfer in these layers can occur in two ways: conduction trough the rocky material or convection by mobile phases, like air or water, in the voids and pores of the material.

Scientists first investigated the site of the Murtel rock glacier, located in the mountains of the Swiss canton of Engadin, in 1970. The area has since become one of the best documented sites for mountain permafrost in the world. Permafrost occurs here below very heterogenous substrate like barren bedrock, vegetated bedrock, debris of a talus slope, fine-grained and coarse-grained debris of two rock glaciers. In a long-term project, geographer Sina Schneider and her team analyzed the temperature profiles of these different substrates, recorded in five boreholes over a period of eight years (2002–2010). The study was published last year in The Cryosphere, an open access journal of the European Geosciences Union.

Photographs of the different surfaces at the borehole locations in the investigation area, taken in summer 2009 (from Schneider et al. 2012).

The results confirmed in part previous observations, but showed also new intriguing finds. Freezing during late autumn and early winter influences significantly the temperature profile in all boreholes, as without an impermeable snow cover cold air can penetrate into the pores of the material. A dry winter with lacking or thin snow cover and rare freezing can therefore be more important for thawing permafrost than a hot summer.

Also the covering material can influence the behavior of the subsurface permafrost. Sites covered with an isolating cover of soil and vegetation showed significantly fewer fluctuations in the temperatures between winter and summer.

Borehole temperature data from 2002–2010 compared to monthly mean air temperature and snow cover. In bedrock the superficial heat (red and green colours) is conducted deep into the underground. Coarse-grained debris (like found at the talus slope or at the rock glaciers) is a relative effective insulator; however in fine-grained debris heat penetrates deep into the underground, causing thawing of permafrost (from Schneider et al. 2012).

In coarse-grained material air circulation in the voids plays a major role, cooling the underground effectively. Both in the coarse-grained debris of the talus slope and in the rock glacier no significant increase of temperatures along the contact between cover and permafrost was observed in eight years. However, it was in fine-grained material that most permafrost thawing occurred. Numerous complex processes, like water infiltration, freezing and air circulation, seem to be especially effective in the small pores of fine-grained sediments and transport heat deep into the underground.

In computer models used to calculate the changes and future distribution of permafrost and permafrost-related natural hazards the composition of the surface is often neglected – in part due the difficulties to gain detailed information in rugged mountain terrains. However the study by Schneider et al. shows that sediment type and size does matter and detailed field survey and data collection play essential parts in understanding the reactions of the hidden permafrost in a warmer climate.

By David Bressan, freelance geologist based in Italy

Imaggeo on Mondays: Sequoias in full moon

25 Jun

Sequoias in full moon by Michael Prather, distributed by EGU under a Creative Commons licence.

The Sequoia National Park in Sierra Nevada, California, is one of the most beautiful wilderness areas in the United States. The park, spanning over 1,600 square kilometres, is home to high mountains, deep canyons, and long and pristine caves. But its most distinct feature are giant sequoias, the world’s largest trees.

Sequoias (Sequoiadendron giganteum) grow to an average height of 50 to 85 metres and have typical diametres of six to nine metres. The Sequoia National Park is home to General Sherman, the world’s largest (in volume) living tree, calculated to have a volume close to 1,500 cubic metres.

The giant trees frame a beautiful starry sky in this photo by Michael Prather. He took this picture in February 2010 during a family holiday to the Wuksachi area of the Sequoia National Park. He explains that the picture was taken the night after a very heavy snow storm. “We spent the weekend in Wuksachi, getting hit with about 24″ [~60cm] of snow overnight. The snow on the trees was heavy and lit up like daylight by the moon.  I was surprised to be able to see Orion so clearly with the near-full moon, but the sky was very clear.”

The lower half of the constellation of Orion is visible at the top centre of the photograph. The three stars that make up the belt of The Hunter appear clearly, and a more careful viewing also reveals the fuzzy Orion nebula – the middle of the three ‘stars’ south of the belt.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Roundup of EGU Twitter Journal Club 1

22 Jun

The EGU’s Twitter Journal Club had its first virtual meeting yesterday, discussing an article on a climate change related blunder made by The Times Comprehensive Atlas of the World and the swift response of an international group of scientists.

You can read a full transcript of our discussion on our brand new Storify page. Even though Twitter went down after an hour’s discussion, we’re optimistic that the TJC will continue to bring out the best of our now-over-1,000 followers!

Greenland ice outlines, from Kargel et al. 2012, published in The Cryosphere, an open-access journal of the European Geosciences Union (6, 533–537, 2012)

The European Geosciences Union, through publishing house Copernicus Publications, publishes 14 peer-reviewed Open Access journalsThe Cryosphere (TC) (IF 3.641)  is an international scientific journal dedicated to the publication and discussion of research articles, short communications and review papers on all aspects of frozen water and ground on Earth and on other planetary bodies.

EGU Twitter Journal Club: Article 1

15 Jun

The EGU is pleased to announce the launch of its Twitter Journal Club, a regular, interactive online discussion about a timely scientific article. Full details can be found here

Our first ever article, described below, covers a climate change related blunder made by The Times Comprehensive Atlas of the World and the swift response of an international group of scientists. The Twitter discussion will take place on Thursday 21 June at 17:00 CEST (hashtag #egutjc1). Please email the EGU’s Science Communications Fellow Edvard Glücksman with further questions. Happy reading!

Greenland ice outlines, from Kargel et al. 2012, published in The Cryosphere, an open-access journal of the European Geoscience Union

Greenland’s shrinking ice cover: “fast times” but not that fast
The Cryosphere, 6, 533–537, 2012

Abstract. A map of Greenland in the 13th edition (2011) of The Times Comprehensive Atlas of the World made headlines because the publisher’s media release mistakenly stated that the permanent ice cover had shrunk 15% since the previous 10th edition (1999) revision. The claimed shrinkage was immediately challenged by glaciologists, then retracted by the publisher. Here we show: (1) accurate maps of ice extent based on 1978/87 aerial surveys and recent MODIS imagery; and (2) shrinkage at 0.019%a−1 in 50 000 km2 of ice in a part of east Greenland that is shown as ice-free in The Times Atlas.

Questions to think about:
1. Broadly, how does this article tie in with the current climate change debate, and the general public’s perception of environmental change?

2. Based on this paper, do you get the impression we need to be worried about Greenland’s ice shrinkage?

3. Do you often catch mistakes in the scientific content given to the general public by respected publishers? If so, what are some examples? Do you challenge them?

4. Here, the authors brought the Greenland map mistake up on www.cryolist.org, an open listserver for glaciologists. Would it be worth setting up a more general communications environment (website, forum etc) where mistakes like this can be reported? Do you know of any currently in use?

5. Is an article like this really necessary (see its final sentence), or are the authors being pedantic or perhaps even exaggerating the importance of the impact of their work?

6. Given all the benefits of online distribution methods (cheaper, easy to correct, wider potential audience), are paper atlases on their way out and, if so, is this a good thing?

Related media coverage
The BBC
The Carbon Brief
The National Review
The Telegraph

The European Geosciences Union, through publishing house Copernicus Publications, publishes 14 peer-reviewed Open Access journalsThe Cryosphere (TC) (IF 3.641)  is an international scientific journal dedicated to the publication and discussion of research articles, short communications and review papers on all aspects of frozen water and ground on Earth and on other planetary bodies.

Imaggeo on Mondays: Halo

11 Jun

Halo by Farahnaz Khosrawi, distributed by the EGU under a Creative Commons License

“Ring around the sun or moon brings rain or snow upon you soon.” Before the development of meteorology, visible atmospheric phenomena, such as halos, were used to forecast the weather. Though meteorological prediction has come a long way since then, these extraordinary halos really do appear in the sky on otherwise ordinary days, a lesson learned by Farahnaz Khosrawi when she saw the sun rise on a cold Swedish morning.

Khosrawi, an Associate Professor at the Department of Meteorology, University of Stockholm, recalls her trip to the office, “A wonderful halo was visible [around the sun] in the early morning of 8 December 2010. It was a very cold winter morning in Stockholm with temperatures around -20 C. The picture was taken in front of the university on my way to work. I couldn’t believe my eyes when I saw this wonderful huge halo. I was so glad that I had my camera with me. I never have seen such an halo before and who knows when I will have the chance to see one again.”

Like rainbows, halos are beautiful optical phenomena. However, unlike rainbows, where sunlight hits atmospheric water droplets, halos are formed when light is reflected and refracted by ice crystals in the thin, wispy cirrus clouds high up in the upper troposphere (5–10 km altitude). Khosrawi explains, “The shape and size of the ice crystals determines the appearance of the halo. The halo produced by the ice crystals appears as an arc or spot in the sky. Many halos occur near the sun but others appear elsewhere and can even appear in the opposite part of the sky.”

Two ‘sundogs’, another atmospheric phenomena that takes the shape of two bright spots of light to the left and right of the sun, are also visible in this stunning picture.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Melt Stream

28 May

Melt Stream, Greenland by Ian Joughin, distributed by the EGU under a Creative Commons license.

Supraglacial lakes are created when water forms in depressions on top of a glacier, remaining there until it dissipates by seeping through crevasses, or cracks in the ice sheet. Despite their sometimes impressive size, supraglacial lakes may drain in a matter of hours under the right conditions, when the pressure they exert on the ice causes it to crack creating a sometimes spectacular lake draining event.

Draining of supraglacial lakes may have important environmental consequences and may even, as warming temperatures further increase meltwater volumes, affect rates of sea-level rise by accelerating the rate by which ice sheets slide into the ocean.

Dr Ian Joughin, from the University of Washington Polar Science Center, took this breathtaking photo under freezing conditions, earning him the 1st Prize at the 2012 General Assembly photo competition. He explains, “This image was taken as part of a project investigating the rapid drainage of supraglacial lakes in Greenland. Each year, these lakes, which often are a few kilometers across and 10 or meters deep, fill with melt water. If the water can find an open crack, it fills the crack and the greater density of water relative to ice allows it to hydro-fracture through the full thickness (~1 km) of the ice sheet, causing the entire lake to drain rapidly (< 2hours). This picture shows a large melt stream that we encountered as we were out exploring the lake basin, and it is only one of many streams feeding the lake.”

Additional images from this trip can be viewed here.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Icy Landscape

21 May

Icy Landscape by Lucien von Gunten, distributed by the EGU under a Creative Commons license.

Ice is a hazardous beauty, ephemeral in nature and, under the right conditions, capable of dominating landscapes. Earlier this year, while North America enjoyed an unusually mild winter, central and eastern Europe experienced brutal cold spells. The continent witnessed widespread freezing as cold air swept south from Siberia, claiming hundreds of lives, knocking out power supplies, and disrupting transport services. In Poland and the Ukraine, temperatures dropped as low as -33C and in Italy over 80,000 citizens were left without electricity after power lines were felled by trees.

This year’s icy spell brought Switzerland its coldest weather since 1987, the year it experienced its lowest ever recorded temperature. Lucien von Gunten, Science Officer at PAGES (Past Global Changes), explains the exceptional circumstances behind this captivating shot, taken earlier this year. “In Versoix, near the Lake of Geneva, the combination of low temperatures and strong easterly winds led to an unusual natural spectacle as the lake shores were partly covered with ice. Images of cars and boats under a thick ice shell were shown in the international press. Next to these popular eye-catchers one could also admire smaller scale ice structure, such as those depicted on this photograph, which covers an area of 30×30 cm.” This photo won 3rd Prize at the 2012 General Assembly photo competition.

Exceptional weather events, such as extreme temperatures, drought, or tropical storms and hurricanes, have increased in frequency over the past 50 years, partly as a result of human-induced climate change.

More pictures of Switzerland during this year’s freeze can be seen here.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Drill cores and climate: An EGU 2012 poster presentation

15 May

In the past few weeks, we have been publishing various reports from the 2012 General Assembly, courtesy of our guest bloggers. Today, we bring you yet another report, in video format this time, produced by the lovely Sue Voice who worked at the press office in Vienna. The video features Otago University’s Christian Ohneiser talking about his PhD project. Christian tells Sue how drill cores, retrieved from remote dry valleys of Antarctica, can help us understand the past climate of the Southern Ocean.

Publications by the EGU

10 May

The EGU is responsible for 14 Open Access journals, all freely available online

Since 2001, the EGU and Open Access publishing house Copernicus Publications has published a growing number of successful geoscientific journals. These include 14 peer-reviewed Open Access journals, of which 11 have a Thomson Reuters Impact Factor, placing them in the top echelon of their respective discipline. EGU also publishes a host of other materials available in paper and online. As a signatory of the Berlin Open Access Declaration (2003), the EGU is committed to making all their publications freely available.

The EGU’s Open Access scientific journals are: