A Curious Cold Layer in the Atmosphere of Venus

The planet Venus is well known for its thick, carbon dioxide atmosphere and oven-hot surface, and as a result is often portrayed as Earth's inhospitable evil twin.

But in a new analysis based on five years of observations using ESA's Venus Express, scientists have uncovered a very chilly layer at temperatures of around -175ºC in the atmosphere 125 km above the planet's surface.

The curious cold layer is far frostier than any part of Earth's atmosphere, for example, despite Venus being much closer to the Sun.

The discovery was made by watching as light from the Sun filtered through the atmosphere to reveal the concentration of carbon dioxide gas molecules at various altitudes along the terminator -- the dividing line between the day and night sides of the planet.

Armed with information about the concentration of carbon dioxide and combined with data on atmospheric pressure at each height, scientists could then calculate the corresponding temperatures.

"Since the temperature at some heights dips below the freezing temperature of carbon dioxide, we suspect that carbon dioxide ice might form there," says Arnaud Mahieux of the Belgian Institute for Space Aeronomy and lead author of the paper reporting the results in the Journal of Geophysical Research.

Clouds of small carbon dioxide ice or snow particles should be very reflective, perhaps leading to brighter than normal sunlight layers in the atmosphere.

"However, although Venus Express indeed occasionally observes very bright regions in the Venusian atmosphere that could be explained by ice, they could also be caused by other atmospheric disturbances, so we need to be cautious," says Dr Mahieux.

The study also found that the cold layer at the terminator is sandwiched between two comparatively warmer layers.

"The temperature profiles on the hot dayside and cool night side at altitudes above 120 km are extremely different, so at the terminator we are in a regime of transition with effects coming from both sides.

"The night side may be playing a greater role at one given altitude and the dayside might be playing a larger role at other altitudes."

Similar temperature profiles along the terminator have been derived from other Venus Express datasets, including measurements taken during the transit of Venus earlier this year.

Models are able to predict the observed profiles, but further confirmation will be provided by examining the role played by other atmospheric species, such as carbon monoxide, nitrogen and oxygen, which are more dominant than carbon dioxide at high altitudes.

"The finding is very new and we still need to think about and understand what the implications will be," says Håkan Svedhem, ESA's Venus Express project scientist.

"But it is special, as we do not see a similar temperature profile along the terminator in the atmospheres of Earth or Mars, which have different chemical compositions and temperature conditions."

Farming Carbon: Study Reveals Potent Carbon-Storage Potential of Human-Made Wetlands

Important as these storage functions of wetlands are, however, another critical one is being overlooked, says Bill Mitsch, director of the Everglades Wetland Research Park at Florida Gulf Coast University and an emeritus professor at Ohio State University: Wetlands also excel at pulling carbon dioxide out of the air and holding it long-term in soil.

Writing in the July-August issue of theJournal of Environmental Quality, Mitsch and co-author Blanca Bernal report that two 15-year-old constructed marshes in Ohio accumulated soil carbon at an average annual rate of 2150 pounds per acre -- or just over one ton of carbon per acre per year.

The rate was 70% faster than a natural, "control" wetland in the area and 26% faster than the two were adding soil carbon five years ago. And by year 15, each wetland had a soil carbon pool of more than 30,000 pounds per acre, an amount equaling or exceeding the carbon stored by forests and farmlands.

What this suggests, Mitsch says, is that researchers and land managers shouldn't ignore restored and human-made wetlands as they look for places to store, or "sequester," carbon long-term. For more than a decade, for example, scientists have been studying the potential of no-tillage, planting of pastures, and other farm practices to store carbon in agricultural lands, which cover roughly one-third of Earth's land area.

Yet, when created wetlands are discussed in agricultural circles, it's almost always in the context of water quality. "So, what I'm saying is: let's add carbon to the list," Mitsch says. "If you happen to build a wetland to remove nitrogen, for example, then once you have it, it's probably accumulating carbon, too."

In fact, wetlands in agricultural landscapes may sequester carbon very quickly, because high-nutrient conditions promote the growth of cattail, reeds, and other wetland "big boys" that produce a lot of plant biomass and carbon, Mitsch says. Once carbon ends up in wetland soil, it can also remain there for hundreds to thousands of years because of water-logged conditions that inhibit microbial decomposition.

"And carbon is a big deal -- any carbon sinks that we find we should be protecting," Mitsch says. "Then we're going even further by saying: We've lost half of our wetlands in the United States, so let's not only protect the wetlands we have remaining but also build some more."

At the same time, he acknowledges that wetlands emit the powerful greenhouse gas (GHG), methane, leading some to argue that wetlands shouldn't be created as a means to sequester carbon and mitigate climate change. But in a new analysis that modeled carbon fluxes over 100 years from the two constructed Ohio marshes and 19 other wetlands worldwide, Mitsch, Bernal, and others demonstrated that most wetlands are net carbon sinks, even when methane emissions are factored in. And among the best sinks were the wetlands in Ohio, possibly due to flow-through conditions that promoted rapid carbon storage while minimizing methane losses, the authors hypothesize.

The concerns about methane emissions and even his own promising findings point to something else, Mitsch cautions: It's easy to undervalue wetlands if we become too focused on just one of their aspects -- such as whether they're net sinks or sources of GHGs. Instead, people should remember everything wetlands do.

"We know they're great for critters and for habitat, that's always been true. Then we found out they cleaned up water, and could protect against floods and storms," he says. "And now we're seeing that they're very important for retaining carbon. So they're multidimensional systems -- even though we as people tend to look at things one at a time."

Carbon Buried in the Soil Rises Again

While earlier studies have found that erosion can bury carbon in the soil, acting as a carbon sink, or storage, the new study published this week in the journal Proceedings of the National Academy of Sciences found that part of that sink is only temporary.

"It's all part of figuring out the global carbon cycle," said co-author Johan Six, professor of plant sciences at UC Davis. "Where are the sources, and where are the sinks? Erosion is in some ways a sink, but, as we found out, it can also become a source."

The researchers estimated that roughly half of the carbon buried in soil by erosion will be re-released into the atmosphere within about 500 years, and possibly faster due to climate change. Climate change can speed the rate of decomposition, aiding the release of the buried carbon.

As a case study, the researchers used radiocarbon and optical dating to calculate the amount of carbon emissions captured in soils and released to the atmosphere during the past 6,000 years along the Dijle River in Belgium.

The study's long time scope -- from 4000 BC to AD 2000 -- allowed the researchers to notice the gradual reintroduction of buried carbon to the atmosphere. Significant agricultural land conversion -- historically the largest source of global erosion -- began primarily in the past 150 years, well under the researchers' time frame of 500 years. Therefore, most carbon sequestered in the soil during the past 150 years of agricultural history has not been released yet but may become a significant carbon source in the future, with implications for soil management, the study said.

"Our results showed that half of the carbon initially present in the soil and vegetation was lost to the atmosphere as a result of agricultural conversion," said study co-author Gert Verstraeten, a professor at KU Leaven, Belgium.

Six noted that erosion could be minimized by no-till and low-till agricultural methods, as well as by cover cropping, which can ensure that soil is not left bare.

"We need to know where and how much carbon is being released or captured in order to develop sensible and cost-effective measures to curb climate change," said lead author, Kristof Van Oost, of the Universite catholique de Louvain in Belgium.

Capturing Carbon With Clever Trapdoors

The quest to capture carbon dioxide is crucial to a cleaner future and once captured, carbon dioxide can be compressed and safely stored. It is also a useful source for chemical manufacture. However, current processes are inefficient and require several stages of refining and extraction before a pure form of carbon dioxide is produced.

One method of capturing carbon dioxide is through molecular sieve, an ultra-fine filter system that captures a variety of molecules but that needs further filtering.

Professor Paul Webley and his team including PhD student Jin Shang and research Fellow Gang Li from the Melbourne School of Engineering, have developed a new sieve that allows carbon dioxide molecules to be trapped and stored.

"The findings published in the Journal of the American Chemical Society suggest that this new material has important applications to natural gas purification. Many natural gas fields contain excess carbon dioxide that must be removed before the gas can be liquefied and shipped, Professor Webley said.

"Because the process allows only carbon dioxide molecules to be captured, it will reduce the cost and energy required for separating carbon dioxide. The technology works on the principle of the material acting like a trap-door that only allows certain molecules to enter, he said.

Once entered, the trapdoor closes and the carbon dioxide molecules remain," said Professor Webley.

"We took a collaborative approach to this research with input from CSIRO, the Department of Materials Engineering and Mechanical Engineering at Monash University and the Australian Synchrotron.

We have a new material that is able to separate carbon, dioxide from any given stream such as power stations and from natural gas sources. While we can't change industry in a hurry, we have provided a viable bridging solution."

A Milestone for New Carbon-Dioxide Capture/Clean Coal Technology

Liang-Shih Fan and colleagues explain that carbon capture and sequestration ranks high among the approaches for reducing coal-related emissions of the carbon dioxide linked to global warming. This approach involves separating and collecting carbon dioxide before it leaves smokestacks. Fan's team has been working for more than a decade on two versions of carbon capture termed Syngas Chemical Looping (SCL) and Coal-Direct Chemical Looping (CDCL).

They involve oxidizing coal, syngas or natural gas in a sealed chamber in the absence of the atmospheric oxygen involved in conventional burning. Metal compounds containing oxygen are in the chamber. They provide the oxygen for oxidation, take up coal's energy, release it as heat in a second chamber and circulate back for another run in the first chamber.

Their report describes the longest continuous operation of the CDCL test system. It operated successfully for 200 hours without an involuntary shutdown. The system used sub-bituminous and lignite coals, which are the main source of carbon dioxide emissions at U.S. coal-fired power plants. Carbon dioxide captured during operation had a purity of 99.5 percent.

Deforestation Activates leads to Carbon Failure of Exotic Peatlands

Exotic peatlands, with their high water platforms and low breaking down rates, form wide shops of natural as well as hundreds of meters dense. Most of it is discovered in Philippines, where the natural swamp jungles (also home to vulnerable creature varieties such as orangutans) will be damaged by deforestation, waterflow and drainage and fire, to make way for farming, in particular oil hand for biofuels and food.

Dr Sam Moore, lead writer of the study and former Open School PhD university student, explained: “We calculated as well as failures in programs depleting unchanged and deforested peatlands, and discovered it is 50 % higher from deforested swamps, in comparison to unchanged swamps. Demolished natural as well as launched from unchanged swamps mainly comes from fresh place content, but as well as from the deforested swamps is much older – hundreds of years to a large number of years – and comes from strong within the peat moss line.”

Deforestation of Oriental peat moss swamps is an important source of co2 pollutants worldwide and its exhaust may be bigger than formerly thought. Carbon dating reveals that the additional as well as missing from deforested swamps comes from peat moss which had been safely saved for hundreds of years. Carbon missing from the waterflow and drainage systems of deforested and cleared peatlands is often not considered in environment return as well as costs, but the research team discovered it improved the approximated total as well as loss by 22 %.  

Changes in the the water pattern seem to be the major car owner of this improve in as well as reduction.  Much of the the water dropping as rainfall would normally keep the environment through transpiration in plants, but deforestation causes it to keep through the peat moss, where it melts non-renewable as well as on its way.

Dr Vincent Gauci, Mature Speaker in World Systems and Ecosystem Technology at The Open School, and corresponding writer said: “Essentially, historical as well as is being demolished out of Oriental peatlands as they will be surrended to farming to meet international requirements for food and biofuels. This has led to a large improve in as well as reduction from South east Oriental waterways depleting peatland environments - up by 32 % over the last 20 years, which is more than half the entire yearly as well as reduction from all Western peatlands.  The devastation of the Oriental peat moss swamps is a worldwide significant ecological catastrophe, but compared with deforestation of the Amazon, few people know that it is happening”. 

The writers determined that their results improve the emergency for defending these environments from continuous devastation for oil hand and other uses. 

Migrating Animals Add New Depth to How the Ocean 'Breathes'

Research begun at Princeton University and recently reported on in the journalNature Geoscience found that animals ranging from plankton to small fish consume vast amounts of what little oxygen is available in the ocean's aptly named "oxygen minimum zone" daily. The sheer number of organisms that seek refuge in water roughly 200- to 650-meters deep (650 to 2,000 feet) every day result in the global consumption of between 10 and 40 percent of the oxygen available at these depths.

The findings reveal a crucial and underappreciated role that animals have in ocean chemistry on a global scale, explained first author Daniele Bianchi, a postdoctoral researcher at McGill University who began the project as a doctoral student of atmospheric and oceanic sciences at Princeton.

"In a sense, this research should change how we think of the ocean's metabolism," Bianchi said. "Scientists know that there is this massive migration, but no one has really tried to estimate how it impacts the chemistry of the ocean.

"Generally, scientists have thought that microbes and bacteria primarily consume oxygen in the deeper ocean," Bianchi said. "What we're saying here is that animals that migrate during the day are a big source of oxygen depletion. We provide the first global data set to say that."

Much of the deep ocean can replenish (often just barely) the oxygen consumed during these mass migrations, which are known as diel vertical migrations (DVMs).

But the balance between DVMs and the limited deep-water oxygen supply could be easily upset, Bianchi said -- particularly by climate change, which is predicted to further decrease levels of oxygen in the ocean. That could mean these animals would not be able to descend as deep, putting them at the mercy of predators and inflicting their oxygen-sucking ways on a new ocean zone.

"If the ocean oxygen changes, then the depth of these migrations also will change. We can expect potential changes in the interactions between larger guys and little guys," Bianchi said. "What complicates this story is that if these animals are responsible for a chunk of oxygen depletion in general, then a change in their habits might have a feedback in terms of oxygen levels in other parts of the deeper ocean."

The researchers produced a global model of DVM depths and oxygen depletion by mining acoustic oceanic data collected by 389 American and British research cruises between 1990 and 2011. Using the background readings caused by the sound of animals as they ascended and descended, the researchers identified more than 4,000 DVM events.

They then chemically analyzed samples from DVM-event locations to create a model that could correlate DVM depth with oxygen depletion. With that data, the researchers concluded that DVMs indeed intensify the oxygen deficit within oxygen minimum zones.

"You can say that the whole ecosystem does this migration -- chances are that if it swims, it does this kind of migration," Bianchi said. "Before, scientists tended to ignore this big chunk of the ecosystem when thinking of ocean chemistry. We are saying that they are quite important and can't be ignored."

Bianchi conducted the data analysis and model development at McGill with assistant professor of earth and planetary sciences Eric Galbraith and McGill doctoral student David Carozza. Initial research of the acoustic data and development of the migration model was conducted at Princeton with K. Allison Smith (published as K.A.S. Mislan), a postdoctoral research associate in the Program in Atmospheric and Oceanic Sciences, and Charles Stock, a researcher with the Geophysical Fluid Dynamics Laboratory operated by the National Oceanic and Atmospheric Administration.

Global Carbon Budget

On Earth, as well as is constantly riding a bike through terrestrial techniques, national rich waters, the sea, and the weather. Until little over a several years ago, when determining the terrestrial component of the international as well as price variety, information were restricted to the sea and the land. Because national the water systems cover less than 1% of the Planet's surface, it was believed that their participation was insignificant.

This perspective was recently pushed in an Environments paper featuring the results of a National Center for Environmental Evaluation and Features research. Carried out by a team of international researchers, including Institution of Environment Studies Biogeochemist Dr. Jonathan J. Cole, the newspaper's mature author, the group shows that national the water systems are essential areas of terrestrial as well as modification that are entitled to addition in international as well as pattern tests.

While waterways were introduced into international as well as price variety tests in the late 90s, Cole and co-workers claim that current designs are restricted by a filter definition of how waterways transport as well as. By illustrating waterways as "pipes" that passively deliver terrestrial as well as to the sea, designs fail to catch the complicated changes that occur on the journey toward the sea. The fact is, according to the writers, that half of the terrestrial as well as coming into national rich waters is intended for a destiny outside of the shoreline's high sodium shoreline.

Where does the staying terrestrial as well as go? Approximately 40% is came back to the weather as CO2 and 12% is saved in sediments. This applies across a variety of national techniques, from waterways to tanks and swamplands. Carbon costs that are based on the inactive pipe perspective are defective because in-system changes fall off the balance sheets. Even if designs were modified to accept a more powerful perspective of stream information, they would need further improving to include the real variety of national rich waters.

Take, for instance, the part performed by ponds and tanks. By burying as well as in their sediments, ponds serve as essential local as well as stores. In combination, ponds play a essential part in the international as well as price variety. On an yearly basis, they hide 40% as much as well as as the sea. Reservoirs, which are continuously increasing in number, hide more natural as well as than all natural pond sinks combined and surpass oceanic natural as well as funeral by more than 1.5-fold.

These results debunk the concept that national rich waters are insignificant when bookkeeping for the international as well as budget; instead they are places of complicated and effective as well as modification. The take home message from the authors: "Continental hydrologic networks, from stream lips to the tiniest upstream tributaries, do not act as fairly neutral pipes-- they are effective players in the as well as pattern despite their moderate size."

As international as well as price variety designs move from fixed boxes to powerful moves, future designs should take into account the variety of ways that national rich waters give rise to the as well as pattern. In many cases, these marine techniques are biogeochemical "hot spots" within the terrestrial landscape with efforts that are essential at local to international machines.