NASA Launches Groundbreaking Soil Moisture Mapper

NASA's Soil Moisture Active Passive (SMAP) observatory lifts off from Space Launch Complex 2 West at California's Vandenberg Air Force Base, beginning a three-year mission to map Earth's vital moisture hidden in the soils beneath our feet. Image credit: NASA/Bill Ingalls

NASA successfully launched its first Earth satellite designed to collect global observations of the vital soil moisture hidden just beneath our feet.

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The Soil Moisture Active Passive (SMAP) observatory, a mission with broad applications for science and society, lifted off at 6:22 a.m. PST (9:22 a.m. EST) Saturday from Vandenberg Air Force Base, California, on a United Launch Alliance Delta II rocket. NASA's Jet Propulsion Laboratory in Pasadena, California, manages SMAP for NASA's Science Mission Directorate in Washington, with instrument hardware and science contributions made by NASA's Goddard Space Flight Center in Greenbelt, Maryland.

About 57 minutes after liftoff, SMAP separated from the rocket's second stage into an initial 411- by 425-mile (661- by 685-kilometer) orbit. After a series of activation procedures, the spacecraft established communications with ground controllers and deployed its solar array. Initial telemetry shows the spacecraft is in excellent health.
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SMAP now begins a three-year mission that will figuratively scratch below Earth's surface to expand our understanding of a key component of the Earth system that links the water, energy and carbon cycles driving our living planet. SMAP's combined radar and radiometer instruments will peer into the top 2 inches (5 centimeters) of soil, through clouds and moderate vegetation cover, day and night, to produce the highest-resolution, most accurate soil moisture maps ever obtained from space.

The mission will help improve climate and weather forecasts and allow scientists to monitor droughts and better predict flooding caused by severe rainfall or snowmelt -- information that can save lives and property. In addition, since plant growth depends on the amount of water in the soil, SMAP data will allow nations to better forecast crop yields and assist in global famine early-warning systems.

"The launch of SMAP completes an ambitious 11-month period for NASA that has seen the launch of five new Earth-observing space missions to help us better understand our changing planet," said NASA Administrator Charles Bolden. "Scientists and policymakers will use SMAP data to track water movement around our planet and make more informed decisions in critical areas like agriculture and water resources."

SMAP also will detect whether the ground is frozen or thawed. Detecting variations in the timing of spring thaw and changes in the length of the growing season will help scientists more accurately account for how much carbon plants are removing from Earth's atmosphere each year.

"The next few years will be especially exciting for Earth science thanks to measurements from SMAP and our other new missions," said Michael Freilich, director of the Earth Science Division of NASA's Science Mission Directorate in Washington. "Each mission measures key variables that affect Earth's environment. SMAP will provide new insights into the global water, energy and carbon cycles. Combining data from all our orbiting missions will give us a much better understanding of how the Earth system works."

SMAP will orbit Earth from pole to pole every 98.5 minutes, repeating the same ground track every eight days. Its 620-mile (1,000-kilometer) measurement swath allows SMAP to cover Earth's entire equatorial regions every three days and higher latitudes every two days. The mission will map global soil moisture with about 5.6-mile (9-kilometer) resolution.

"SMAP will improve the daily lives of people around the world," said Simon Yueh, SMAP project scientist at JPL. "Soil moisture data from SMAP has the potential to significantly improve the accuracy of short-term weather forecasts and reduce the uncertainty of long-term projections of how climate change will impact Earth's water cycle."

The SMAP team is engaged with many organizations and individuals that see immediate uses for the satellite's data. Through workshops and tutorials, the SMAP Applications Working Group is collaborating with 45 "early adopters" to test and integrate the mission's data products into many different applications. Early adopters include weather forecasters from several nations, as well as researchers and planners from the U.S. Department of Agriculture, U.S. Geological Survey, U.S. Centers for Disease Control and Prevention, and the United Nations World Food Programme.

During the next 90 days, SMAP and its ground system will be commissioned to ensure they are fully functional and are ready to begin routine science data collection. A key milestone will be the deployment of the spacecraft's instrument boom and 20-foot-diameter (6-meter) reflector antenna. The observatory will be maneuvered to its final 426-mile (685-kilometer), near-polar operational orbit, and the antenna will spin up to 14.6 revolutions per minute.

SMAP science operations will then begin, and SMAP data will be calibrated and validated. The first release of SMAP soil moisture data products is expected within nine months. Fully validated science data are expected to be released within 15 months.

SMAP's Delta II rocket also carried a JPL CubeSat into orbit. The GRIFEX (Geostationary Coastal and Air Pollution Events Read-Out Integrated Circuit In-Flight Performance Experiment) CubeSat was one of three NASA-sponsored CubeSat missions successfully deployed during the launch. About the size of a loaf of bread, GRIFEX will validate cutting-edge detector technology for use in future Earth-observing satellites.

JPL built the SMAP spacecraft and is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument and science data products. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center at the University of Colorado in Boulder. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida was responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena.

Source: Nasa

Building a Better Weather Forecast? SMAP May Help

SMAP's soil moisture measurements will help with forecasts of precipitation and temperature. Image credit: UCAR

If you were trying to forecast tomorrow's weather, you would probably look up at the sky rather than down at the ground. But if you live in the U.S. Midwest or someplace with a similar climate, one key to a better weather forecast may lie beneath your feet.

Precipitation and temperature are part of every weather forecast. Precipitation comes from clouds, clouds are formed of airborne water vapor, and vapor comes from evaporating soil moisture -- so soil moisture governs precipitation. Evaporating soil moisture also makes air cooler, so it affects temperature. In certain kinds of climate, scientists believe, soil moisture is so influential that better observations of it might improve weather forecasts. These climates are transitional: not too humid and not too dry. For example, the agriculturally productive states of the U.S. Midwest fall into that category.

"Better soil moisture observations lead to better land-atmosphere interaction in weather forecasting models and ultimately to a better prediction of temperature and precipitation," said Michael Ek, leader of the Land Hydrology Team at the Environmental Monitoring Center of the National Oceanic and Atmospheric Administration (NOAA). "Weather models need good initial observations of the land surface, or you're starting from the wrong place."

Better soil moisture observations are just what the Soil Moisture Active Passive (SMAP) mission will provide. Scheduled for launch on Jan. 29, SMAP will collect the most accurate and highest-resolution soil moisture measurements ever made from a satellite SMAP will cover the entire globe in two to three days. Ek is a member of one of five groups in SMAP's Early Adopter program that have been working for several years on the question of how best to incorporate the new data into national weather forecasting models.

Forecasts will not improve, however, the moment SMAP starts collecting data. U.S. Department of Agriculture research scientist Wade Crow, a member of SMAP's science team, explained that, since closely spaced global soil moisture measurements have never existed before, the mathematical models used in weather forecasting are not configured to include them directly. Getting the best use out of the new observations has been a subject of active research for several years and will require some significant changes in how soil moisture data are assimilated into the models.

Data assimilation is necessary because weather forecasting models all drift a bit, like cars. If you're driving on a perfectly straight road, you still need to keep a hand on the steering wheel or you'll run off the edge sooner or later. Data assimilation in a model serves the same purpose as the slight movements of your hands that keep your car on course.

Drift is not a fatal flaw for a weather forecasting model any more than it is for a car. It is simply a sign that the Earth system is too vast and complicated to model perfectly with the resources available today. To steer forecasts toward greater realism, models ingest, or assimilate, real-world data and use them in sophisticated mathematical techniques. Each time updated observations become available, they are assimilated to improve the starting point for the next forecast.

Closely spaced and highly accurate global measurements are an important part of the process. For soil moisture, however, current observations are not on a fine enough scale to meet the needs of weather forecasting models directly. "Modelers compensate for the lack of direct observations of soil moisture by using more indirect measures, such as estimating it from observations of temperature and precipitation," Crow explained. "As a consequence, modeled soil moisture tends to diverge from reality. SMAP will be directly observing the state that they want, so they won't have to back it out from proxy measurements."

JPL scientist Eni Njoku is working with researchers at another forecasting center, the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, England. Njoku said, "SMAP will provide benefits of higher soil moisture accuracy and spatial resolution than have previously been available from satellites. This could lead potentially to improved regional and global weather forecasts by ECMWF." Environment Canada, the branch of the Canadian government responsible for weather forecasting in that nation, is also working on assimilating SMAP data into its models.

"The numerical weather prediction centers are adapting to the new availability of soil moisture information and thinking of ways they can exploit it," Crow summarized. "It will be really exciting to see what they find."

SMAP is managed for NASA's Science Mission Directorate in Washington by the agency's Jet Propulsion Laboratory in Pasadena, California, with instrument hardware and science contributions made by NASA's Goddard Space Flight Center in Greenbelt, Maryland. JPL is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center, at the University of Colorado in Boulder, for public distribution and archiving. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida is responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena.

Source: Nasa

New Online Course Explores Social and Ecological Diversity of Himalayan Region

The conversion of forests into cropland worldwide has triggered an atmospheric change that, while seldom considered in climate models, has had a net cooling effect on global temperatures, according to a new Yale study.

Writing in the journal Nature Climate Change, Professor Nadine Unger of the Yale School of Forestry & Environmental Studies (F&ES) reports that large-scale forest losses during the last 150 years have reduced global emissions of biogenic volatile organic compounds (BVOCs), which control the atmospheric distribution of many short-lived climate pollutants, such as tropospheric ozone, methane, and aerosol particles.

Using sophisticated climate modeling, Unger calculated that a 30-percent decline in BVOC emissions between 1850 and 2000, largely through the conversion of forests to cropland, produced a net global cooling of about 0.1 degrees Celsius. During the same period, the global climate warmed by about 0.6 degrees Celsius, mostly due to increases in fossil fuel carbon dioxide emissions.

According to her findings, the climate impact of declining BVOC emissions is on the same magnitude as two other consequences of deforestation long known to affect global temperatures, although in opposing ways: carbon storage and the albedo effect. The lost carbon storage capacity caused by forest conversion has exacerbated global warming. 
Meanwhile, the disappearance of dark-colored forests has also helped offset temperature increases through the so-called albedo effect. (The albedo effect refers to the amount of radiation reflected by the surface of the planet. Light-colored fields, for instance, reflect more light and heat back into space than darker forests.)

“Without doing an earth-system model simulation that includes these factors, we can’t really know the net effect on the global climate.”— Nadine Unger

Unger says the combined effects of reduced BVOC emissions and increased albedo may have entirely offset the warming caused by the loss of forest-based carbon storage capacity.

“Land cover changes caused by humans since the industrial and agricultural revolutions have removed natural forests and grasslands and replaced them with croplands,” said Unger, an assistant professor of atmospheric chemistry at F&ES. “And croplands are not strong emitters of these BVOCs — often they don’t emit any BVOCs.”

“Without doing an earth-system model simulation that includes these factors, we can’t really know the net effect on the global climate. Because changes in these emissions affect both warming and cooling pollutants,” she noted.

Unger said the findings do not suggest that increased forest loss provides climate change benefits, but rather underscore the complexity of climate change and the importance of better assessing which parts of the world would benefit from greater forest conservation.

Since the mid-19th century, the percentage of the planet covered by cropland has more than doubled, from 14 percent to 37 percent. Since forests are far greater contributors of BVOC emissions than crops and grasslands, this shift in land use has removed about 30 percent of Earth’s BVOC sources, Unger said.

Not all of these compounds affect atmospheric chemistry in the same way. Aerosols, for instance, contribute to global “cooling” since they generally reflect solar radiation back into space. Therefore, a 50 percent reduction in forest aerosols has actually spurred greater warming since the pre-industrial era.

“[These emissions] don’t get as much attention as human-generated emissions... but if we change how much forest cover exists, then there is a human influence on these emissions.”— Nadine Unger

However, reductions in the potent greenhouse gases methane and ozone — which contribute to global warming — have helped deliver a net cooling effect.

These emissions are often ignored in climate modeling because they are perceived as a “natural” part of the earth system, explained Unger. “So they don’t get as much attention as human-generated emissions, such as fossil fuel VOCs,” she said. “But if we change how much forest cover exists, then there is a human influence on these emissions.”

These impacts have also been ignored in previous climate modeling, she said, because scientists believed that BVOC emissions had barely changed between the pre-industrial era and today. But a study published last year by Unger  showed that emissions of these volatile compounds have indeed decreased. Studies by European scientists have produced similar results.

The impact of changes to ozone and organic aerosols are particularly strong in temperate zones, she said, while methane impacts are more globally distributed.

The sensitivity of the global climate system to BVOC emissions suggests the importance of establishing a global-scale long-term monitoring program for BVOC emissions, Unger noted.

– Kevin Dennehy    kevin.dennehy@yale.edu    203 436-4842

Source: Yale University

Scientists call for soil mapping program to help Indian agriculture

Delegates to the University's agriculture workshop at Kharagpur

Scientists attending an agriculture workshop in India organised by the University of Sydney have called for a detailed soil mapping program to help policy makers and farmers draw up effective land management proposals.

The Soil and Water National Networking Workshop, organised jointly with the Indian Institute of Technology at Kharagpur, involved 40 scientists from India and Australia.

They discussed key issues including soil security, digital soil mapping, India's participation in the Global Soil Map project, national level spectral libraries, soil data requirement in crop simulations, soil health mapping, hydrological model behaviour, and using soil digital and satellite data for hydrologic models.

A number of speakers urged India to participate in the Global Soil Map and accelerate the provision of fine scale information on soil fertility and conditions in India. The information could also be used to monitor and understand the change over time in soil nutrients.

The workshop's soil group was led by Professor Budiman Minasny, Professor Bhabani Das and Dr Kanika Singh from the University of Sydney. The hydrology group was led by A/Professor Willem Vervoort from Sydney, Dr Rajib Maity and Mr Dipangkar Kundu.

The workshop was launched with a welcome video by Professor Alex McBratney, the Dokuchaev award winner in Soil Science, who is actively involved with the Global Soil Map.

Dr Singh said: "The workshop was a great success; the Indian scientists showcased high quality research and are open to future collaboration in the Global Soil Map effort.

"The director of IIT Kharagpur in his speech talked about a joint collaboration between India and Australia for a comprehensive digitisation of soil information contributing to soil security and sustainable productivity. The Assistant Director General of the Indian Council of Agricultural Research is also keen to developIndian collaboration in the Global Soil Map effort.

"We look forward to long-term collaboration with IIT Kharagpur and other such organisations in India to achieve collaborative research."

The workshop was sponsored by the Australia-India Council.

Contact: Richard North
Phone: 02 9351 3191
Email: richard.north@sydney.edu.au

 Source: THE UNIVERSITY OF SYDNEY

Soil mineral surfaces linked to key atmospheric processes

Pictured are, from left, are David Bish, Melissa Donaldson and Jonathan Raff. Credit: Indiana University

Research by Indiana University scientists finds that soil may be a significant and underappreciated source of nitrous acid, a chemical that plays a pivotal role in atmospheric processes such as the formation of smog and determining the lifetime of greenhouse gases.

The study shows for the first time that the surface acidity of common minerals found in soil determines whether the gas nitrous acid will be released into the atmosphere. The finding could contribute to improved models for understanding and controlling air pollution, a significant public health concern.

"We find that the surfaces of minerals in the soil can be much more acidic than the overall pH of the soil would suggest," said Jonathan Raff, assistant professor in the School of Public and Environmental Affairs and Department of Chemistry. "It's the acidity of the soil minerals that acts as a knob or a control lever, and that determines whether nitrous acid outgasses from soil or remains as nitrite."

The article, "Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid," will be published this week in the journal Proceedings of the National Academy of Sciences. Melissa A. Donaldson, a Ph.D. student in the School of Public and Environmental Affairs, is the lead author. Co-authors are Raff and David L. Bish, the Haydn Murray Chair of Applied Clay Mineralogy in the Department of Geological Sciences.

Nitrous acid, or HONO, plays a key role in regulating atmospheric processes. Sunlight causes it to break down into nitric oxide and the hydroxyl radical, OH. The latter controls the atmospheric lifetime of gases important to air quality and climate change and initiates the chemistry leading to the formation of ground-level ozone, a primary component of smog.
Scientists have known about the nitrous acid's role in air pollution for 40 years, but they haven't fully understood how it is produced and destroyed or how it interacts with other substances, because HONO is unstable and difficult to measure.

"Only in the last 10 years have we had the technology to study nitrous acid under environmentally relevant conditions," Raff said.

Recent studies have shown nitrous acid to be emitted from soil in many locations. But this was unexpected because, according to basic chemistry, the reactions that release nitrous acid should take place only in extremely acidic soils, typically found in rain forests or the taiga of North America and Eurasia.

The standard method to determine the acidity of soil is to mix bulk soil with water and measure the overall pH. But the IU researchers show that the crucial factor is not overall pH but the acidity at the surface of soil minerals, especially iron oxides and aluminum oxides. At the molecular level, the water adsorbed directly to these minerals is unusually acidic and facilitates the conversion of nitrite in the soil to nitrous acid, which then volatilizes.

"With the traditional approach of calculating soil pH, we were severely underestimating nitrous acid emissions from soil," Raff said. "I think the source is going to turn out to be more important than was previously imagined."

The research was carried out using soil from a farm field near Columbus, Ind. But aluminum and iron oxides are ubiquitous in soil, and the researchers say the results suggest that about 70 percent of Earth's soils could be sources of nitrous acid.

Ultimately, the research will contribute to a better understanding of how nitrous acid is produced and how it affects atmospheric processes. That in turn will improve the computer models used by the U.S. Environmental Protection Agency and other regulatory agencies to control air pollution, which the World Health Organization estimates contributes to 7 million premature deaths annually.

"With improved models, policymakers can make better judgments about the costs and benefits of regulations," Raff said. "If we don't get the chemistry right, we're not going to get the right answers to our policy questions regarding air pollution."

Source: Indiana University

Earthworms, ants, termites: The real engineers of the ecosystem

The contribution of home gardens in the preservation of biodiversity, economics and human health prompted a multidisciplinary group at the South Border College (Ecosur) in Mexico to work on a project in Tabasco, a south state of the country, with the aim to improve the production and environmental management of these plantations. Credit: Image courtesy of Investigación y Desarrollo

The contribution of home gardens in the preservation of biodiversity, economics and human health prompted a multidisciplinary group at the South Border College (Ecosur) in Mexico to work on a project in Tabasco, a south state of the country, with the aim to improve the production and environmental management of these plantations.

Although the research was conducted from different perspectives, head of research Esperanza Huerta Lwanga focused on the study of soil invertebrates because they are indicators of its quality.

"These organisms fulfill various functions,like allowing the soil to absorb processed organic matter such as leaves, wood, trunks and branches and with this nourishing crops; they also maintain an ecological balance capable of preventing the invasion of pests and provide greater fertility without using chemicals. This happens when growing different types of plants, allowing the existence of a wide variety of soil invertebrates" the researcher explains.

The project, which began in 2009 and was funded by the Ministry of Energy, Natural Resources and Environmental Protection (SERNAPAM), arises because home gardens are places where there is a wealth of soil. In total, the research team worked in 50 home gardens located in different physiographic regions of the state: mountains, coast, floodplain and hillocks.

"During the fieldwork I realized that the orchards whose owners had family harmony, were characterized by a rich vegetation and greater diversity of soil invertebrates was found. However, in other orchards we observed garbage instead vegetation and organisms, revealing a gap between people and nature, " relates Huerta Lwanga.

An important finding of this project was when the researcher found a anecic earthworm, initially thought to be a new species, however, it was only a new entry in the state of Tabasco. "Such organism is characterized by its vertical movements, thereby creating tunnels, helping to integrate the organic matter in the soil, aerating it and forming its structure," the researcher says.

Other species were also identified, like earthworms, ants, termites, centipedes, beetles, grasshoppers, cockroaches and woodlice, which may also be called "ecosystem engineers" (specifically earthworms, termites and some ants) because their activities modify the soil, enriching its productivity.

According to the researcher, it is important to note that the presence of such organisms does not mean that the garden is infested with pests. "If you let me live there, they fulfill their tasks and at the same time control their population because the variety of invertebrates generates food chains."

The pest problem, she says, appears when the land is handled as a monoculture. In these cases only one type of organisms thrives and rapidly increases in number and , because nobody eats them, they become a threat to the plantations.

The research results revealed that the coastal region was the one with more garbage, followed by the hillocks. "In the mountains we found healthy vegetation and a great variety of crops, high diversity of invertebrates and greater earthworm biomass, which was estimated at more than 33 grams per square meter," highlights Huerta Lwanga.

That amount is important because according to previous studies it was established that if biomass is equal or greater than 30 grams per square meter germination induction and plant growth are achieved.

Additionally, this project included environmental education, which was given by mini-workshops and training in the production of vermi-compost.

"At Ecosur, we designed a box for composting, which is equiped with a small mill and worms, where we place the fresh waste to be processed. A device like this was given to all farmers, but was only accepted by 47 percent of them," she sadly concludes.

Source: Investigación y Desarrollo

Live fast, die young: Soil microbes in a warmer world

Aerial view of the Northern Minnesota landscape including numerous conifer peatlands, deciduous uplands and lakes. Credit: USDA Forest Service Northern Research Station

Warmer temperatures shorten the lifespan of soil microbes and this may affect soil carbon storage, according to a new NSF-funded study published in Nature Climate Change this week.

A research team led by Shannon Hagerty and Paul Dijkstra from Northern Arizona University measured two key characteristics of soil microbes that determine their role in the soil carbon cycle: how efficiently they use carbon to grow and how long they live. "Higher temperatures make microbes grow faster, but they also die faster," said Hagerty, who conducted the research as part of her master's degree and was lead author on the study.

Soil microbes consume organic carbon compounds in soil, use some of it to make more microbes and release the rest to the atmosphere as carbon dioxide. The efficiency with which microbes use their food to make new microbes affects how much carbon remains in soil, and how much is released back to the atmosphere. The accepted idea before this study was that microbes would become less efficient at warmer temperatures.

The scientists incubated soil from a peatland and a forest in Minnesota at different temperatures and measured the efficiency with which microbes grew. They used a new method to measure microbial efficiency: they added small amounts of sugar and tracked how individual atoms in this sugar were turned into carbon dioxide.

"Microbes process sugars in similar ways as we do," says Paul Dijkstra. "We know very well how these processes work in laboratory studies, and can predict which carbon atoms in sugar molecules end up as carbon dioxide, and which are used to build new microbes. We applied this knowledge to the microbes living in soil."

The researchers found, contrary to expectation, that temperature had no effect on how microbes utilized their food, but instead boosted microbial death. "We don't yet know why microbes are dying faster at higher temperatures. Maybe they are eaten by nematodes or mites, or they die because of viruses," said Hagerty. "We need to know more about how temperature affects microbial death."

To explore what these new findings could mean for soil carbon storage in a warming world, the team compared output from a soil model that includes the effect of temperature on microbial lifespan to models unaffected by temperature change. "Models are used to predict how soil processes change, for example, in response to climate change," said Steve Allison, coauthor from the University of California, Irvine. "If we want to predict the future correctly, we'd better use models that accurately describe these microbial processes."

Including a temperature-dependent lifespan to the model increased the amount of carbon retained in soils at warmer temperatures compared to estimates from traditional models. The study concludes that incorporating this new insight into soil models will improve our understanding of how soils influence atmospheric carbon dioxide levels and global climate.

Does this mean that with climate change, more carbon will stay in the soil? "Too early to tell," said Bruce Hungate, Director of the Center for Ecosystem Science and Society at NAU. 

"The results suggest that the biochemistry of the microbes remains the same with warmer temperature, but that predation and death become more important. This laboratory study is just the first step, identifying a potential mechanism. Now we need to study how, in the real world, and in the long-term, the processes of biochemical efficiency and lifespan will change. And nobody has done that yet."

Source: Northern Arizona University

Sunlight, not microbes, key to carbon dioxide in Arctic

Terrestrial organic matter is shown spilling into a lake. Credit: Image courtesy of Oregon State University

The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial activity.

However, a new study -- funded by the National Science Foundation and published this week in the journal Science -- concludes that sunlight and not bacteria is the key to triggering the production of CO2 from material released by Arctic soils.

The finding is particularly important, scientists say, because climate change could affect when and how permafrost is thawed, which begins the process of converting the organic carbon into CO2.

"Arctic permafrost contains about half of all the organic carbon trapped in soil on the entire Earth -- and equals an amount twice of that in the atmosphere," said Byron Crump, an Oregon State University microbial ecologist and co-author on the Science study. "This represents a major change in thinking about how the carbon cycle works in the Arctic."

Converting soil carbon to carbon dioxide is a two-step process, notes Rose Cory, an assistant professor of earth and environmental sciences at the University of Michigan, and lead author on the study. First, the permafrost soil has to thaw and then bacteria must turn the carbon into greenhouse gases -- carbon dioxide or methane. While much of this conversion process takes place in the soil, a large amount of carbon is washed out of the soils and into rivers and lakes, she said.

"It turns out, that in Arctic rivers and lakes, sunlight is faster than bacteria at turning organic carbon into CO2," Cory said. "This new understanding is really critical because if we want to get the right answer about how the warming Arctic may feedback to influence the rest of the world, we have to understand the controls on carbon cycling.

"In other words, if we only consider what the bacteria are doing, we'll get the wrong answer about how much CO2 may eventually be released from Arctic soils," Cory added.

The research team measured the speed at which both bacteria and sunlight converted dissolved organic carbon into carbon dioxide in all types of rivers and lakes in the Alaskan Arctic, from glacial-fed rivers draining the Brooks Range to tannin-stained lakes on the coastal plain. Measuring these processes is important, the scientists noted, because bacteria types and activities are variable and the amount of sunlight that reaches the carbon sources can differ by body of water.

In virtually all of the freshwater systems they measured, however, sunlight was always faster than bacteria at converting the organic carbon into CO2.

"This is because most of the fresh water in the Arctic is shallow, meaning sunlight can reach the bottom of any river -- and most lakes -- so that no dissolved organic carbon is kept in the dark," said Crump, an associate professor in Oregon State's College of Earth, Ocean, and Atmospheric Sciences. "Also, there is little shading of rivers and lakes in the Arctic because there are no trees."

Another factor limiting the microbial contribution is that bacteria grow more slowly in these cold, nutrient-rich waters.

"Light, therefore, can have a tremendous effect on organic matter," University of Michigan's Cory pointed out.

The source of all of this organic carbon is primarily tundra plants -- and it has been building up for hundreds of thousands of years, but doesn't completely break down immediately because of the Arctic's cold temperatures. Once the plant material gets deep enough into the soil, the degradation stops and it becomes preserved, much like peat.

"The level of thawing only gets to be a foot deep or so, even in the summer," Crump said. "Right now, the thaw begins not long before the summer solstice. If the seasons begin to shift with climate change -- and the thaw begins earlier, exposing the organic carbon from permafrost to more sunlight -- it could potentially trigger the release of more CO2."

The science community has not yet been able to accurately calculate how much organic carbon from the permafrost is being converted into CO2, and thus it will be difficult to monitor potential changes because of climate change, they acknowledge.

"We have to assume that as more material thaws and enters Arctic lakes and rivers, more will be converted to CO2," Crump said. "The challenge is how to quantify that."

Some of the data for the study was made available through the National Science Foundation's Arctic Long-Term Ecological Research project, which has operated in the Arctic for nearly 30 years.

Source:  Oregon State University

Impact of climate change on the soil ecosystem

The Basque Institute for Agricultural Research and Development NEIKER-Tecnalia has had a Microbial Observatory in the Ordesa and Monte Perdido National Nature Reserve (Huesca Pyrenees) since 2011. Its purpose is to evaluate the impact of climate change on the ecosystems of the soil by monitoring its microbial properties over time. Credit: Image courtesy of Basque Research

The Basque Institute for Agricultural Research and Development NEIKER-Tecnalia has had a Microbial Observatory in the Ordesa and Monte Perdido National Nature Reserve (Huesca Pyrenees) since 2011. Its purpose is to evaluate the impact of climate change on the ecosystems of the soil by monitoring its microbial properties over time. The research areas are located at altitudes of between 1,500 and 2,600 metres, which provides a broad range of different climate conditions and makes it possible to observe how the altitude affects the properties of the soil and the micro-organisms living in it. Preliminary results indicate that microbial properties are highly dependent on the physical and chemical properties of the soil on a small scale and on the environmental conditions existing at the moment when the samples are gathered.

To conduct this research, NEIKER-Tecnalia is using the most advanced techniques in the matter of molecular biology, which have revolutionised microbial ecology. Specifically, massive sequencing analyses are being carried out right now; they allow a large number of genes to be sequenced and identified within a short space of time. The genetic sequencing of the subterranean biosphere is seeking to gain a better understanding of the structure and function of the microbial communities across the altitude gradient.

NEIKER-Tecnalia's Microbial Observatory will contribute towards improving the current understanding of the effects of climate change on soil microbial communities and associated ecological processes. The alpine area where it is located is particularly suitable for a climate change observatory. Firstly, it is a remote spot relatively isolated from direct anthropogenic impacts, which means that global effects like climate change can be clearly perceived without the interference of more local environmental factors. Secondly, the altitude gradients that exist in the mountains in turn create clearly marked climate gradients within short distances; in other words, different climate conditions can be found at different altitudes.

Micro-organisms adapt more quickly than plants and macro-organisms

Micro-organisms adapt more quickly to changes than plants or other macro-organisms, which means they are ideal bioindicators of the impact of sources of environmental stress on the functioning of ecosystems. It is very important to have a record of the alterations gradually occurring in the soil ecosystem as a result of climate change to be able to more accurately predict what future scenarios are going to be in store. It is important to stress that the soil is our most important resource; it is the basis of the terrestrial ecosystem and 95% of our food comes directly or indirectly from it.

The role of micro-organisms in relation to the functioning of the soil ecosystem is fundamental. The soil, which has been traditionally regarded as an inanimate item made up of minerals and chemical substances, contains a myriad of micro-organisms that are responsible for many of its vital functions and, consequently, its health. These functions include the decomposition and recycling of nutrients from dead plant and animal tissue, nitrogen fixing, the maintaining of soil structure and the elimination of contaminants.
It can be predicted that, in the long term, climate change will cause the biota of mountain soil to migrate towards higher altitudes in the quest for the optimum bioclimatic environment. The problem is that this migration has a limit, which is the summit of the mountain, beyond which no migration or escape is possible.

Source:  Basque Research