GeoLog

Antarctica

Imaggeo on Mondays: An expedition to better understand Antarctic soils

Imaggeo on Mondays: An expedition to better understand Antarctic soils

A dramatic evening sky puts the frame to a photo taken during the Brazilian Antarctic expedition to James Ross Island in 2016. Brazilian palaeontologists and soil scientists together with German soil scientists spent over 40 days on the island to search for fossils and sample soils at various locations of the northern part of the island.

The island was named after Sir James Clark Ross who led the British expedition in 1842, which first charted locations at the eastern part of the island. James Ross Island is part of Graham Land, the northern portion of the Antarctic Peninsula, separated from South America by the stormy Drake sea passage.

Map of the Antarctic Peninsula featuring the James Ross Archipelago (Credit: The Scientific Committee on Antarctic Research, Antarctic Digital Database Map Viewer)

This photo was taken in the northern Ulu Peninsula, which is the northernmost part of the relatively large James Ross Island and the largest ice-free area in the Antarctic Peninsula region. The island’s characteristic appearance is formed by Late Neogene volcanic rocks (3-7 million years old) over fossil rich Late Cretaceous sandstones (66-120 million years old).

In the photo we are looking from a higher marine terrace at the Santa Martha Cove, the ‘home’ to the 2016 Brazilian Antarctic expedition, towards the steep cliffs of Lachman Crags, a characteristic mesa formed by Late Neogene lava flows. The Lachman Crags mesa, the Spanish word for tablelands, dominates the landscape of the northern part of the Ulu Peninsula. Above the cliffs visible in the photo, a glacier covered plateau stretches to the Northwest.

The marine terrace on which the tent is standing is comprised of a flat area that has been ice-free for approximately 6000 years and thus makes for a great model system to study soil development after glacial retreat. The ground is composed of a mixture of volcanic rocks and Cretaceous sandstones rich in all sorts of fossils, from fossilised wood to shark teeth, ammonites and reptile bones.

The strong winds that can start in Antarctica from one moment to the other and the very low precipitation led to the characteristic desert pavement, with stones sorted in a flat arrangement on top of the fine textured, deeply weathered permafrost soils. Although these soils host a surprisingly high number of microorganisms, most terrestrial life is restricted to wetter areas surrounding fresh water lakes and melt water streams. Thus lakes and snow meltwater-fed areas make for higher primary production of algae and mosses, fostering biodiversity and soil development by organic matter input.

As there are no larger bird rookeries on James Ross Island the only way sea-derived nutrients reach the Ulu Peninsula is by a rather grim feature:  dead seal carcasses that lie distributed across the lowlands (< 150 m asl) of the Ulu Peninsula. Carcasses fertilise the soils in their direct vicinity while slowly decomposing over decades, thus feeding small patches of lichens and mosses within the barren cold arid desert. The region is thus an illustration of the harsh Antarctic environment where even Weddell seals, animals that are well adapted for the living in dense pack ice during the polar night, die when losing track on land on the way to the water.

By Carsten Müller, Technical University of Munich Chair of Soil Science, Germany

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: Monitoring Antarctica’s ocean current

Imaggeo on Mondays: Monitoring Antarctica’s ocean current

This week’s featured image depicts a quiet and still oceanic landscape in Antarctica, but polar scientists are studying how energetic and variable the ocean currents in this part of the world can be.

In this picture, the marine research vessel RRS James Clark Ross is making its way through the Lemaire Channel, a small passage off the coast of the Antarctic Peninsula, south of the southernmost tip of Chile. This channel is about 11 kilometres long and just 1,600 metres wide at its narrowest point, bordered by a spectacular range of steep cliffs.

At the time this photo was taken, the ship was headed to the Rothera Research Station, a British Antarctic Survey base on the white continent’s peninsula. The scientists aboard the vessel are part of a decades-long research campaign surveying the ocean current surrounding Antarctica, known as the Antarctic Circumpolar Current (ACC). The ACC is the world’s strongest and most influential current, transporting 165 million to 182 million cubic metres of water every second and connecting most of Earth’s major oceans. As such, any changes to the ACC have the potential to impact other marine environments around the world.

For more than 25 years, scientists from the UK’s National Oceanography Centre (NOC) have ventured south each Antarctic summer to measure the ocean’s physical features in one region of the Southern Ocean, called the Drake Passage. Spanning just 800 kilometres between the Falkland Islands and the Antarctic Peninsula, the Drake Passage is the shortest crossing from Antarctica to any other landmass. This makes it a prime spot to survey the ocean’s currents, as the flow is constricted to a narrow geographical region.

So far, researchers have completed 24 survey trips across the passage. The data collected during these trips have been used to assess how physical features of the ACC change, both throughout a single year and over the course of several years. Yvonne Firing at NOC leads the latest expeditions as part of the UK funded ORCHESTRA project. The continuation of this monitoring is helping scientists study how the ocean stores excess heat and carbon. No other ocean basin has been monitored so consistently, making the Drake Passage the most comprehensively studied part of the Southern Ocean.

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: Penguins – a biogeochemical link between sea and land

Imaggeo on Mondays: Penguins – a biogeochemical link between sea and land

A couple of Chinstrap penguins (Pygoscelis antarctica) at their nesting site on Deception Island, maritime Antarctica. Sea birds contribute importantly to biogeochemical cycles in coastal ecosystems and on islands. Feeding on the marine food chain and nesting on land, they carry large amounts of marine nutrients into terrestrial ecosystems. This might be of particular importance for the nitrogen (N) cycle of terrestrial ecosystems in the antarctic. In the form of ammonia, marine derived N can travel far inland with the wind, and perhaps represent an important nutrient source for the growth of mosses.

Description by Daniel Wasner, 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/.

April GeoRoundUp: the best of the Earth sciences from the 2019 General Assembly

April GeoRoundUp: the best of the Earth sciences from the 2019 General Assembly

The EGU General Assembly 2019 took place in Vienna last month, drawing more than 16,000 participants from 113 countries. This month’s GeoRoundUp will focus on some of the unique and interesting stories that came out of research presented at the Assembly!

Major Stories

Glacial disappearing act in the European Alps

New research from a team of scientists estimated the future of all glaciers within the European Alps, and the results aren’t that hopeful. After running new simulations and analysing observational data, the researchers predict that, if we limit global warming below 2°C above pre-industrial levels, by 2100 glacier volume in the Alps would be roughly two-thirds less than levels seen today.

Furthermore, according to the new research, if we fail to put global warming in check, more than 90 percent of Europe’s glacier volume in the Alps will disappear by the end of the century. “In this pessimistic case, the Alps will be mostly ice free by 2100, with only isolated ice patches remaining at high elevation, representing 5 percent or less of the present-day ice volume,” says Matthias Huss, a researcher at ETH Zurich and co-author of the study.

Evolution of total glacier volume in the European Alps between 2003 and 2100. Credit: Zekollari et al., 2019, The Cryosphere.

The data also suggests that from now until 2050, about 50 percent of the present glacier volume will melt, regardless of how much greenhouse gas emissions we produce in the coming years. This is because glaciers are slow to respond to changes in climate conditions, and still reflect colder climates from the past. In addition to presenting their research at the EGU General Assembly, the team also published the results in The Cryosphere.

The search for the oldest ice announces their drill site

Ice-core extraction near Concordia station (Credit: Thibaut Vergoz, French Polar Institute, CNRS)

After three years of careful consideration, a collection of European ice and climate researchers have pinpointed the spot where they would most likely uncover the oldest ice core possible, one that dates back to 1.5 million years from today.

The consortium of researchers, also known as the Beyond-EPICA project, hopes to pull out a sample of ice containing a seamless record of Earth’s climate history. Such ice samples contain trapped air bubbles, some sealed off thousands to millions of years ago, thus providing undisturbed snapshots into Earth’s ancient atmospheres. Using this climate data, researchers can make predictions on how Earth’s will warm in the future.

At the General Assembly, the scientists formally announced that the drilling operation will be conducted 40 kilometres southwest from the Dome Concordia Station, which is run jointly by France and Italy. The team plans to collect a three km-long ice core from the site, nicknamed ‘Little Dome C,’ over the course of five years, then will spend at least an additional year examining the ice.

Map of Antarctica showing the areas surveyed by BE-OI and the selected drill site (Credit: British Antarctic Survey (BAS))

 

What you might have missed

Predicting the largest quakes on Earth

Scientists have long discussed how intense quakes can be on Earth, with some studies suggesting that Earth’s tectonic features cannot generate earthquakes larger than magnitude 10. However, new research conducted by Álvaro González Center from Mathematical Research in Barcelona, Spain estimates that subduction zones, regions where one tectonic plate is pushed under another, subsequently sinking into the mantle, have the potential to release 10.4 magnitude earthquakes. González’ analysis suggests that such events happen on average every 2,000 years.

“Such events would produce especially large tsunamis and long lasting shaking which would effect distant locations,” Gonzalez said to the Agence France-Presse.

His findings also propose that large asteroid impacts, such as the dinosaur-killing Chicxulub event 66 million years ago, may trigger even larger magnitude shaking. According to data analysis, shaking events reaching magnitude 10.5 or more likely happen on average once every 10 million years.

Where deadly heat will hit the hardest

Heatwaves and heat-related hazards are expected to be more prevalent and more severe as the Earth warms, and a team of researchers looked into which regions of the world will be the most vulnerable.

The scientists specifically analysed human exposure to ‘deadly heat,’ where temperatures as so high that humans aren’t able to cool down anymore. By examining data projections for future population growth and annual days of deadly heat, the researchers assessed which areas will be hit the hardest. They found that, if global warming isn’t limited to 2°C above pre-industrial levels, there will be a few ‘hots spots,’ where large populations are predicted to experience frequent days of deadly heat annually.

Dhaka, Bangladesh, is expected to experience significant exposure to deadly heat in the future, according to research presented at the EGU 2019 meeting. Credit: mariusz kluzniak via Flickr

The research results suggest that future deadly heat will most significantly impact the entire South Asia and South-East Asia region, Western Africa and the Caribbean. Sub-Saharan Africa in particular will experience big increases in deadly heat exposure, due to climate change and population growth.

The researchers also found that a minority of large cities in very poor countries will be the most affected by future heat conditions. “There is a big inequality of who takes the toll of deadly heat,” said Steffen Lohrey, a PhD student at the Technical University Berlin who presented the findings at the EGU meeting.

Europe and the Mediterranean at risk of malaria due to climate change

While malaria was eradicated in Europe and the Mediterranean in the 20th century, there have been an increasing number of new cases in this region of the world, primarily due to international travel and immigration. New research presented at the General Assembly by Elke Hertig, a professor at the University of Augsburg, Germany, suggests that Europe’s future climate may further increase the risk of local malaria recurrence and expansion.

Malaria is transmitted to humans by Anopheles mosquitos and these disease-carrying insects are very sensitive to temperature and precipitation conditions. In particular, these mosquitos thrive in areas with warm spring temperatures and high precipitation in the summer and autumn.

Using climate models, Hertig found that the malaria-carrying mosquito population will likely spread northward as Europe’s climate changes, reaching much of northern Europe by the end of the century. Alternatively, her models suggest that mosquito populations will decline in the Mediterranean regions, mainly due to decreases in summer and autumn rainfall.

A statistical analysis also revealed that, by the end of the century, disease transmission from mosquitoes will be the most effective in southern and south-eastern European regions, including parts of Spain, southern France, Italy, Greece, and the Balkan countries.

Other noteworthy stories

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