Warming climate may release vast amounts of carbon from long-frozen Arctic soils

Michael Sullivan at the University of Georgia Today: While climatologists are carefully watching carbon dioxide levels in the atmosphere, another group of scientists is exploring a massive storehouse of carbon that has the potential to significantly affect the climate change picture.

University of Georgia Skidaway Institute of Oceanography researcher Aron Stubbins is part of a team investigating how ancient carbon, locked away in Arctic permafrost for thousands of years, is now being transformed into carbon dioxide and released into the atmosphere. The results of the study were published in Geophysical Research Letters.

The Arctic contains a massive amount of carbon in the form of frozen soil—the remnants of plants and animals that died more than 20,000 years ago. Because this organic material was permanently frozen year-round, it did not undergo decomposition by bacteria the way organic material does in a warmer climate. Just like food in a home freezer, it has been locked away from the bacteria that would otherwise cause it to decay and be converted to carbon dioxide.

"However, if you allow your food to defrost, eventually bacteria will eat away at it, causing it to decompose and release carbon dioxide," Stubbins said. "The same thing happens to permafrost when it thaws."

Scientists estimate there is more than 10 times the amount of carbon in the Arctic soil than has been put into the atmosphere by burning fossil fuels since the start of the Industrial Revolution. To look at it another way, scientists estimate there is two and a half times more carbon locked away in the Arctic deep freezer than there is in the atmosphere today. Now, with a warming climate, that deep freezer is beginning to thaw and that long-frozen carbon is beginning to be released into the environment.

"The study we did was to look at what happens to that organic carbon when it is released," Stubbins said. "Does it get converted to carbon dioxide or is it still going to be preserved in some other form?"

..."We found that decomposition converted 60 percent of the carbon in the thawed permafrost to carbon dioxide in two weeks," Stubbins said. "This shows the permafrost carbon is definitely in a form that can be used by the microbes."...

Permafrost thaw ponds in Hudson's Bay, shot by Steve Jurvetson, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license 

Indigenous people measure carbon that satellites miss

Bjorn Carey in Futurity via Stanford University: Indigenous people govern about half of all remaining undeveloped land on the planet. New research with indigenous people in the Amazon suggests they may outperform satellites in measuring the true carbon storage potential of the rainforest. That finding could influence how indigenous people in Guyana and elsewhere manage their forests and may lead to greater opportunities for these communities to engage in carbon offset programs.

The project, described in the journal Forest Ecology and Management, grew out of efforts to engage indigenous peoples to gain better understanding of ecosystems that have been relatively undisturbed by modern civilization. ...“The people know the trails really well, and some of them will walk two days to get to their plot and make measurements,” Fragoso says. “They can make really good measurements in really isolated areas, where government workers would never get to. Generally, professional scientists will not travel these distances on foot to verify carbon estimates.”

While satellite observations would most likely identify each of these plots as “forest” and assigned them a standardized value for carbon storage, the field workers identified 11 habitat types with trees, each of which requires a different set of calculations for determining its carbon storage potential. Because they could be more specific about the biomass of each vegetation type making up a plot, they were able to calculate that forests in Guyana contain 20 to 40 percent more carbon than previously estimated.

...These areas probably play a much larger role in the global climate than previously assumed, Fragoso says, and indigenous people need to be better represented at global climate talks. These land-owners have more carbon storage at their disposal to sell as carbon credits to governments and corporations looking to offset their greenhouse gas-producing activities.

...This is the first model for turning indigenous people into field researchers capable of producing scientifically rigorous calculations for carbon, says Fragoso, who is now planning to share the concept with other indigenous nations around the world.

Rainforest in Guyana, shot by Loriski, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Epic survey finds regional patterns of soot and dirt on North American snow

C. Dang in EurekAlert via the University of Washington: Snow is not as white as it looks. Mixed in with the reflective flakes are tiny, dark particles of pollution. University of Washington scientists recently published the first large-scale survey of impurities in North American snow to see whether they might absorb enough sunlight to speed melt rates and influence climate.

The results, published in the Journal of Geophysical Research, show that North American snow away from cities is similar to Arctic snow in many places, with more pollution in the U.S. Great Plains. They also show that agricultural practices, not just smokestacks and tailpipes, may have a big impact on snow purity.

During their almost 10,000-mile trek across North American snowfields, the researchers were particularly interested in the Bakken oil fields of northwest North Dakota. "With all this oil exploration, diesel trucks and new oil wells, people wondered: Is there a huge amount of air pollution making the snowpack darker?" said lead author Sarah Doherty, a research scientist at the UW's Joint Institute for the Study of the Atmosphere and Ocean.

What they found was that these activities do appear to be adding extra soot to the snow, but perhaps just as important is the dirt. Disturbance from clearing oil pads, new housing sites and all the extra truck traffic on unpaved roads means dirtier snow. But even away from the oil fields, soil is disturbed by agriculture. "Our work suggests that land use and farming practices might matter as much as diesel emissions in many parts of the Great Plains," Doherty said.

....Their main focus was black carbon, a very light-absorbing particle emitted by burning diesel, coal or wood. Many countries have regulated black carbon because of its effects on air quality and human health, but more recently climate scientists also have become interested because the tiny particles darken the snow and hasten melting. The cleanest samples they collected were from northern Canada, with overall levels of black carbon, or soot, similar to that of Arctic snowpack. The Pacific Northwest and Rocky Mountain states had levels slightly higher. The Great Plains readings were more variable and sometimes two to three or more times higher than in other parts of the country, typically 15 to 70 nanograms of soot per gram of snow....

A snowy landscape in Theodore Roosevelt National Park in North Dakota. National Park Service photo

Good news on forests and carbon dioxide

NASA: A new NASA-led study shows that tropical forests may be absorbing far more carbon dioxide than many scientists thought, in response to rising atmospheric levels of the greenhouse gas. The study estimates that tropical forests absorb 1.4 billion metric tons of carbon dioxide out of a total global absorption of 2.5 billion -- more than is absorbed by forests in Canada, Siberia and other northern regions, called boreal forests.

"This is good news, because uptake in boreal forests is already slowing, while tropical forests may continue to take up carbon for many years," said David Schimel of NASA's Jet Propulsion Laboratory, Pasadena, California. Schimel is lead author of a paper on the new research, appearing online today in the Proceedings of National Academy of Sciences.

Forests and other land vegetation currently remove up to 30 percent of human carbon dioxide emissions from the atmosphere during photosynthesis. If the rate of absorption were to slow down, the rate of global warming would speed up in return.

The new study is the first to devise a way to make apples-to-apples comparisons of carbon dioxide estimates from many sources at different scales: computer models of ecosystem processes, atmospheric models run backward in time to deduce the sources of today's concentrations (called inverse models), satellite images, data from experimental forest plots and more. The researchers reconciled all types of analyses and assessed the accuracy of the results based on how well they reproduced independent, ground-based measurements. They obtained their new estimate of the tropical carbon absorption from the models they determined to be the most trusted and verified.

...The question of which type of forest is the bigger carbon absorber "is not just an accounting curiosity," said co-author Britton Stephens of the National Center for Atmospheric Research, Boulder, Colorado. "It has big implications for our understanding of whether global terrestrial ecosystems might continue to offset our carbon dioxide emissions or might begin to exacerbate climate change."

As human-caused emissions add more carbon dioxide to the atmosphere, forests worldwide are using it to grow faster, reducing the amount that stays airborne. This effect is called carbon fertilization. "All else being equal, the effect is stronger at higher temperatures, meaning it will be higher in the tropics than in the boreal forests," Schimel said....

Deep forest in Malaysia, shot by Ksmuthukrishnan, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 4.0 International license

Buckyballs enhance carbon capture

A press release from Rice University: Rice University scientists have discovered an environmentally friendly carbon-capture method that could be equally adept at drawing carbon dioxide emissions from industrial flue gases and natural gas wells.

The Rice lab of chemist Andrew Barron revealed in a proof-of-concept study that amine-rich compounds are highly effective at capturing the greenhouse gas when combined with carbon-60 molecules. The research is the subject of an open-access paper today in Nature’s online journal Scientific Reports.

“We had two goals,” Barron said. “One was to make the compound 100 percent selective between carbon dioxide and methane at any pressure and temperature. The other was to reduce the high temperature needed by other amine solutions to get the carbon dioxide back out again. We’ve been successful on both counts.”

Tests from one to 50 atmospheric pressures showed the Rice compound captured a fifth of its weight in carbon dioxide but no measurable amount of methane, Barron said, and the material did not degrade over many absorption/desorption cycles.

Carbon-60, the soccer ball-shaped molecule also known as buckminsterfullerene (or the “buckyball”) was discovered at Rice by Nobel Prize laureates Richard Smalley, Robert Curl and Harold Kroto in 1985. The ultimate curvature of buckyballs may make them the best possible way to bind amine molecules that capture carbon dioxide but allow desirable methane to pass through.

The Rice lab used buckyballs as crosslinkers between amines, nitrogen-based molecules drawn from polyethyleneimine. The lab produced a brown, spongy material in which hydrophobic (water-avoiding) buckyballs forced the hydrophilic (water-seeking) amines to the outside, where passing carbon dioxide could bind to the exposed nitrogen.

When Barron and his team began combining carbons and amines several years ago, they noticed an interesting progression: Flat graphene absorbed carbon dioxide well, multiwalled nanotubes absorbed it better, and thinner single-walled nanotubes even better. “That suggested the curvature was important,” Barron said. “C-60, being a sphere, has the highest possible curvature among carbon materials.”...

Carbon-60 molecules, also known as buckyballs, were combined with amines in a compound that absorbs a fifth of its weight in carbon dioxide. It shows potential as an environmentally friendly material for capturing carbon from natural gas wells and industrial plants. (Courtesy of the Barron Research Group/Rice University)

Researchers create more accurate model for greenhouse gases from peatlands

A press release from Argonne National Laboratory: Scientists at the U.S. Department of Energy’s Argonne National Laboratory have created a new model to more accurately describe the greenhouse gases likely to be released from Arctic peatlands as they warm. Their findings, based on modeling how oxygen filters through soil, suggest that previous models probably underestimated methane emissions and overrepresented carbon dioxide emissions from these regions.

Peatlands, common in the Arctic, are wetlands filled with dead and decaying organic matter. ...Cold temperatures keep the carbon locked in the soil. As the ground warms, however, microbes come to life and begin to decompose all that organic matter, which releases carbon into the atmosphere. Unfortunately, the extreme northern regions of the world are where warming has accelerated the most quickly—and it’s expected to pick up in the future. Scientists are concerned that Arctic warming could spiral quickly into a self-reinforcing cycle that dumps an enormous amount of carbon into the atmosphere.

...Up until now, researchers had been using a simple model that assumed water was the primary divider; soil above the water table would produce microbes that made CO2, and microbes below would produce methane. “But experiments had been showing that there could be significant limits on oxygen availability above the water ta
ble, and this would affect what form of carbon microbes release,” Fan said.

The size and characteristics of soil particles matter. If the oxygen gets trapped in air bubbles and consumed by other microbes or can’t filter down through soil, soil microbes will produce methane even if they’re above the water table. “So we set out to make a model that would take these findings into account,” Fan said.

The team used experimental data from peatland taken near Fairbanks, Alaska and plugged it into their model. The results showed their new model was much more accurate and suggested that more methane is produced and proportionally less CO2—than predicted by older water table-based models. “Revising this calculation will substantially affect current greenhouse gas production models in the Arctic,” Fan said....

Looks like a bulldozer sinking into thawing muskeg in Alaska, shot by Wyoherminator, public domain

With few data, Arctic carbon models lack consensus

A press release from NASA's Jet Propulsion Laboratory: As climate change grips the Arctic, how much carbon is leaving its thawing soil and adding to Earth's greenhouse effect? The question has long been debated by scientists. A new study conducted as part of NASA's Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) shows just how much work still needs to be done to reach a conclusion on this and other basic questions about the region where global warming is hitting hardest.

Lead author Josh Fisher of NASA's Jet Propulsion Laboratory, Pasadena, California, analyzed 40 computer models of the amounts and flows of carbon in the Alaskan Arctic and boreal ecosystems. His team found wide disagreement among the models, highlighting the urgent need for more measurements from the region.

Models represent scientists' integrated understanding of Earth processes and systems. They are used both to test that understanding, by comparing their results with real-world observations, and to gain insight into how current trends may affect our planet's future.

"We all knew there were big uncertainties in our understanding, and we wanted to quantify their extent," said Fisher. That extent proved to be greater than almost anyone expected. "The results were shocking to most people," he said.

However, pinpointing the extent and areas of uncertainty is the first step toward reducing them. Fisher noted that he has shared preliminary results with the modelers who participated in the study, and some have already used the results as an opportunity to rethink how they are representing Arctic processes in global models. Moreover, the uncertainty maps that the study produced, showing the specific Arctic regions where the disagreement is greatest, highlight key locations for field campaigns to collect data.

The study, which involved 30 co-authors from around the world, examined how well the models agreed on various factors, such as the rate of plant growth and the amount of carbon exchanged between living things and the atmosphere. They also evaluated the performance of the models against measurements of carbon at monitoring sites along the tundra of the Alaskan North Slope.

"If all the models agree with the observations, uncertainty is probably pretty low. If they wildly disagree, uncertainty is pretty high," Fisher said. "The models were all over the board."....

Tundra in the Russian Arctic on Bolshaya Muksalma Island, shot by Aleksander Kaasik, Wikimedia Commons, under the Creative Commons 3.0 license 

Chile becomes first South American country to tax carbon

The Thomson Reuters Foundation via Reuters: President Michelle Bachelet of Chile enacted new environmental tax legislation on Friday making the country the first in South America to tax carbon dioxide (CO2) emissions. Part of a broad tax reform, Chile's carbon tax will target the power sector, particularly generators operating thermal plants with installed capacity equal or larger than 50 megawatts (MW).

These installations will be charged $5 per tonne of carbon dioxide (CO2) released. Thermal plants fueled by biomass and smaller installations will be exempt. The new tax is meant to force power producers to gradually move to cleaner sources to help reduce the country's greenhouse gas emissions and meet its voluntary target of cutting these gases 20 percent from 2007 levels by 2020.

Earlier this year, Mexico imposed a tax on the sale of several fossil fuels, based on their carbon content, averaging $3 per tonne of CO2. In Mexico, companies are able to use carbon credits to reduce their tax bills, a provision not considered in Chile.

Central-American country Costa Rica also has an environmental tax, but it targets gasoline sales. Around 80 percent of Chile's energy is based on fossil fuels, mostly imported oil and coal....

Santiago's skyline, shot by 3BRBS, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Black carbon ups risk of cardiovascular diseases in women

Benita Matilda in Science World Report: Black carbon is found worldwide and is often produced from biomass burning, cooking with solid fuels and diesel exhausts. Since black carbon is the leading cause of respiratory illness and premature mortality, researchers at the McGill University investigated the effects of black carbon pollutant on the health of women cooking with traditional wood stoves.

Highlighting the detrimental effects of black carbon, the researchers claim that this pollutant elevates the risk of cardiovascular disease in women. They based their finding on the daily exposure to various types of air pollutants, including black carbon, in 280 women residing in China's rural Yunnan province.

The team basically focused on the health consequences of these air pollutants that are emitted from sources common in developingcountries.

"China's unprecedented economic growth is fuelling massive increases in industrial and motor vehicle pollution, and 700 million Chinese homes still cook with wood and coal fuels. The Chinese government is setting new targets to improve its air quality. We wanted to identify the pollution sources that most impact human health to help inform these pollution control efforts." said study lead McGill Professor Jill Baumgartner....

A chulla cookstove in Tamil Nadu, shot by mckaysavage, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Viruses take down massive algal blooms - and a whole lot of carbon dioxide

Scientific Blogging: ...Using a combination of satellite imagery and laboratory experiments, researchers have evidence showing that algae is sucking up climate-warming carbon dioxide from the atmosphere and sinking it to the bottom of the ocean.  And for that, we can thank one other thing people dislike: viruses.

Viruses infecting those algae are driving the life-and-death dynamics of the algae's blooms, even when all else stays essentially the same. According to results reported in Current Biology, a single North Atlantic algal bloom, about 30 kilometers in radius, converted 24,000 tons of carbon dioxide from the atmosphere into organic carbon - a process known as carbon fixation.

Two-thirds of that carbon turned over within a week as that bloom grew at a very rapid rate and then quickly met its demise. A closer look at those algae revealed high levels of specific viruses infecting their cells. To put that in context, Assaf Vardi of the Weizmann Institute of Science in Israel says that this patch of ocean fixes about as much carbon as an equivalent patch of rainforest and then almost immediately turns much of it over.

"This is, of course, only one patch out of numerous co-occurring patches in other parts of the Atlantic Ocean," adds Ilan Koren, also of the Weizmann Institute, not to mention those algal blooms that appear in other seasons and ecosystems. "While the impact that viruses have on the entire ecosystem was previously estimated to be very large, we provide the first approach to quantify their immense impact on open ocean blooms."

Important questions remain about the ultimate fate of all that carbon taken in by algal blooms, the researchers say. Much of it is probably recycled back to the atmosphere by bacteria. But it's also possible that the virus-infected algae release sticky sugars and lipids, leading their cells and the carbon within them to sink faster to the ocean floor. "If the latter scenario is true, it will have a profound impact [on] the efficiency of carbon dioxide 'pumping' from the atmosphere to the deep ocean," Vardi says. "This carbon will then have a better chance [of being] buried in the ocean sediment."...

An algal bloom off the Volga delta in the Caspian Sea, shot by NASA

OCO-2 Lifts off on carbon-counting mission

Steven Siceloff at NASA: A Delta II rocket blazed off the launch pad at Vandenberg Air Force Base in California early Wednesday morning to begin a landmark mission to survey carbon dioxide gas in Earth's atmosphere.

NASA's Orbiting Carbon Observatory-2, or OCO-2, is expected to provide insight into how the planet adjusts to the increased production of carbon dioxide from a vantage point in orbit that will allow it to take readings on a scale never achieved before.

While ground stations have been monitoring carbon dioxide concentrations, OCO-2 will be the first spacecraft to conduct a global-scale reading over several seasons. The spacecraft is expected to produce detailed readings to provide regional sources of carbon dioxide as well as sinks for the greenhouse gas.

"There's quite a lot of urgency to see what we can get from a satellite like OCO-2," said David Crisp, the science team lead for the mission.

...The mission is the first of its kind in the agency's extensive history of Earth-observing spacecraft. The spacecraft was launched to replace the first OCO that did not make it into orbit due to an anomaly in February 2009. The spacecraft carries one instrument and its sole focus is detecting carbon dioxide and watching from space as the Earth "breathes" to see what becomes of the gas.

The instrument is precise enough that researchers will be able to count the number of carbon dioxide molecules in the layers of the atmosphere and use the data to draw conclusions about how the increasing amount of gas will affect things like the global temperature. OCO-2's mission is to last at least two years....

OCO-2's liftoff from Vandenberg Air Force Base, image by NASA

Tropical trees absorb 2 billion tons of carbon yearly

Futurity via the University of Leeds (posted by Sarah Reed): Reducing deforestation in the tropics would significantly cut the amount of carbon dioxide emitted into the atmosphere by as much as one-fifth, research shows. In the first study of its kind, scientists have calculated the amount of carbon absorbed by the world’s tropical forests and the amounts of greenhouse gas emissions created by loss of trees, as a result of human activity.

Scientists analyzed data from previous studies, including satellite studies, to determine the amount of carbon absorbed and emitted by the world’s tropical forests in South and Central America, equatorial Africa, and Asia.

“Forest census data from an Amazon-wide network of forest plots, maintained by the Universities of Leeds and Oxford, played a critical part in the analysis,” says Professor Emanuel Gloor, a coauthor of the study from the School of Geography at the University of Leeds. The research appears in Global Change Biology.

The researchers found that tropical forests absorb almost two billion tons of carbon each year, equivalent to one-fifth of the world’s carbon emissions, by storing it in their bark, leaves, and soil.

However, an equivalent amount is lost through logging, clearing of land for grazing, and growing biofuel crops such as palm oil, soy beans, and sugar. Peat fires in forests add significantly to the greenhouse gas emissions. Researchers say emissions from tropical forests will increase as the climate warms, as rising temperatures accelerate the decay of dead plants and trees, giving off more carbon dioxide.

...“If we limit human activity in the tropical forests of the world, this could play a valuable role in helping to curb the rise in carbon dioxide in the atmosphere. Preventing further losses of carbon from our tropical forests must remain a high priority,” says Professor John Grace of the University of Edinburgh’s School of GeoSciences, who led the study....

Deforestation in Kalimantan, Indonesia, shot by Josh Estey of AusAID, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license

Deep-buried carbon may pose climate risk

Terra Daily via AFP: Stocks of organic carbon buried deep underground could pose a global warming threat if disturbed by erosion, farming, deforestation, mining or road-building, a study warned Sunday Scientists from the United States and Germany discovered one such reserve in Nebraska, up to 6.5 metres (21 feet) under the surface, composed mainly of vast quantities of burnt plant material.

"We found almost comparable amounts of carbon stored in this deep soil layer than we would in the top one metre of soil under a grassland vegetation," study co-author Erika Marin-Spiotta of the University of Wisconsin-Madison told AFP. The find suggested "that we are potentially grossly underestimating how much carbon is stored belowground in our global inventories."

Such ancient fossil soils are found all over the world under river, volcano and other sediments, said Marin-Spiotta. Most will remain buried, but some will be exposed over time. Carbon in soil can be released as Earth-warming carbon dioxide into the atmosphere through microbial decomposition, which is more common closer to the Earth surface than deep down.

"Only recently have scientists become more concerned about deep soil carbon as we are finding it is more reactive than we ever imagined," said Marin-Spiotta. Most research is done in the top 30 centimetres of soil. "Our study shows that burial over time can lead to very high amounts of carbon in depths beyond those inventoried," she added....

Graphite, image by Jurii, Wikimedia Commons, under the Creative Commons 3.0 license

Dryland ecosystems emerge as driver in global carbon cycle

University of Montana News Service: Dryland ecosystems, which include deserts to dry-shrublands, play a more important role in the global carbon cycle than previously thought. In fact, they have emerged as one of its drivers, says Montana State University faculty member Ben Poulter.

Surprised by the discovery, Poulter and his collaborators explained their findings in Nature. At the same time, they urged global ecologists to include the emerging role of dryland ecosystems in their research. Nature is a weekly international journal that publishes peer-reviewed research in all fields of science and technology.

"Our study found that natural events in Australia were largely responsible for this anomaly," Poulter said. "La Nina-driven rainfall during 2010 and 2011, as well as the 30-year greening up of its deserts and other drylands contributed to significant changes across the globe.”

...He realized ... that the world’s land carbon sink in 2011 seemed to be absorbing an unusually large amount of carbon, Poulter said. Carbon dioxide moves constantly between land, oceans, vegetation and the atmosphere. When one of those absorbs more carbon dioxide than it releases, it’s referred to as a carbon sink.

Poulter and his collaborators investigated the phenomena with a variety of data sets and modeling approaches. They eventually discovered surprising interactions between climate extremes and desert greening that increased in importance over the past 30 years.  Further study showed that the dryland systems in the Southern Hemisphere, specifically Australia, had particularly high productivity in response to increased La Nina-phase rainfall.

“What surprised us was that no analogous biosphere response to similar climatic extremes existed in the past 30 years, prompting us to explore whether documented dryland-greening trends were responsible for changes in the carbon cycle dynamics,” said Philippe Ciais, co-author and senior scientist at LSCE.

...“Dryland systems have high rates of carbon turnover compared to other biomes,” Ciais said. “We can expect the carbon to be quickly respired or consumed in wildfires, already partly reflected by the high atmospheric carbon dioxide growth rate in 2012.”...

A kangaroo warning sign on Stuart Highway in Northern Territory, Australia, shot by Jpp, Wikimedia Commons, under Creative Commons 3.0 license

Researchers question published no-till soil organic carbon sequestration rates

A press release from the University of Illinois: For the past 20 years, researchers have published soil organic carbon sequestration rates.  Many of the research findings have suggested that soil organic carbon can be sequestered by simply switching from moldboard or conventional tillage systems to no-till systems. However, there is a growing body of research with evidence that no-till systems in corn and soybean rotations without cover crops, small grains, and forages may not be increasing soil organic carbon stocks at the published rates.

“Some studies have shown that both moldboard and no-till systems are actually losing soil organic carbon stocks over time,” said University of Illinois soil scientist Ken Olson who led the review.

The review was conducted by a team of senior researchers from universities in Illinois, Wisconsin, Iowa, and Ohio who studied the published soil science and tillage literature related to soil organic carbon sequestration, storage, retention, and loss. After examining hundreds of original research and summary papers, 120 papers on all sides of the soil organic carbon sequestration, storage, retention, and loss issue were selected for review and analysis.

Olson explained that the difference between the no-till and moldboard plots at the end of a long-term study is only a measure of net soil organic carbon storage difference between treatments and does not support soil organic carbon sequestration claims. No-till systems on sloping and eroding sites retain more soil organic carbon in the surface from 0 to 15 centimeters when compared to moldboard as a result of less disturbance and less soil erosion and transport of soil organic carbon-rich sediment off the plots....

Arid areas absorb unexpected amounts of carbon

Eric Sorensen in the WSU News: Researchers led by a Washington State University biologist have found that arid areas, among the biggest ecosystems on the planet, take up an unexpectedly large amount of carbon as levels of carbon dioxide increase in the atmosphere. The findings give scientists a better handle on the earth’s carbon budget – how much carbon remains in the atmosphere as CO2, contributing to global warming, and how much gets stored in the land or ocean in other carbon-containing forms.

“It has pointed out the importance of these arid ecosystems,” said R. Dave Evans, a WSU professor of biological sciences specializing in ecology and global change. “They are a major sink for atmospheric carbon dioxide, so as CO2 levels go up, they’ll increase their uptake of CO2 from the atmosphere. They’ll help take up some of that excess CO2 going into the atmosphere. They can’t take it all up, but they’ll help.”

The findings, published in the journal Nature Climate Change, come after a novel 10-year experiment in which researchers exposed plots in the Mojave Desert to elevated carbon-dioxide levels similar to those expected in 2050. The researchers then removed soil and plants down to a meter deep and measured how much carbon was absorbed. “We just dug up the whole site and measured everything,” said Evans.

...The work addresses one of the big unknowns of global warming: the degree to which land-based ecosystems absorb or release carbon dioxide as it increases in the atmosphere. ...Overall, said Evans, rising CO2 levels may increase the uptake by arid lands enough to account for 4 to 8 percent of current emissions....

The Cima Dome landscape in the Mojave National Preserve in California, shot by Stan Shebs, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license

Ocean food web key in global carbon cycle

Julie Cohen in the UC Santa Barbara Current: Nothing dies of old age in the ocean. Everything gets eaten and all that remains of anything is waste. But that waste is pure gold to oceanographer David Siegel, director of the Earth Research Institute at UC Santa Barbara.

In a study of the ocean’s role in the global carbon cycle, Siegel and his colleagues used those nuggets to their advantage. They incorporated the lifecycle of phytoplankton and zooplankton — small, often microscopic animals at the bottom of the food chain — into a novel mechanistic model for assessing the global ocean carbon export. Their findings appear online in the journal Global Biogeochemical Cycles.

The researchers used satellite observations including determinations of net primary production (NPP) — the net production of organic matter from aqueous carbon dioxide (CO2) by phytoplankton — to drive their food-web-based model. The scientists focused on the ocean’s biological pump, which exports organic carbon from the euphotic zone — the well-lit, upper ocean — through sinking particulate matter, largely from zooplankton feces and aggregates of algae. Once these leave the euphotic zone, sinking into the ocean depths, the carbon can be sequestered for a season or for centuries.

“What we’ve done here is create the first step toward monitoring the strength and efficiency of the biological pump using satellite observations,” said Siegel, who is also a professor of marine science in UCSB’s Department of Geography. “The approach is unique in that previous ways have been empirical without considering the dynamics of the ocean food web.” The space/time patterns created by those empirical approaches are inconsistent with how oceanographers think the oceans should work, he noted.

...“Quantifying this carbon flux is critical for predicting the atmosphere’s response to changing climates,” Siegel said. “By analyzing the scattering signals that we got from satellite measurements of the ocean’s color, we were able to develop techniques to calculate how much of the biomass occurs in very large or very small particles.”

...The researchers are taking their model one step further by planning a major field program designed to better understand the states in which the biological pump operates. “Understanding the biological pump is critical,” Siegel concluded. “We need to understand where carbon goes, how much of it goes into the organic matter, how that affects the air-sea exchanges of CO2 and what happens to fossil fuel we have emitted from our tailpipes.”...

Shown are the links among the ocean’s biological pump and pelagic food web. Light blue waters are the euphotic zone, while the darker blue waters represent the twilight zone. Photo Credit: Courtesy of the U.S. Joint Global Ocean Flux Study

Drought, fires affect the ability of Amazon to hold carbon dioxide

PhysOrg: Fires in the Amazon could jeopardize the forest's ability to soak up carbon dioxide emissions even as deforestation there slows down, according to a Penn State geographer.

In an invited commentary in the Feb. 6 edition of Nature, Jennifer Balch, assistant professor of geography, noted that dry weather conditions, coupled with fires, may mean that over time the Amazon forest will lose its ability to take in more carbon dioxide than it releases—going from being a carbon sink to a source.

"Aircraft have just recently captured the 'breath' of the entire Amazon forest," Balch said. "This is really important work that represents the first time that carbon fluxes from the Amazon basin have been obtained in this way."

Her commentary follows the work of researchers (whose findings are published in that edition of Nature) who used aircraft to profile how much carbon the forests are releasing. During drought conditions, the forests took up less of the carbon dioxide that comes with fires. That, coupled with a slowdown in photosynthesis, saw an upswing in carbon dioxide emissions from the forest dome.

An important next step, Balch wrote, is determining what types of fires—wildfires or those used for agriculture, for example—are behind the large amount of land that is burned every year. That information could help direct fire prevention and management in the future. Since the year 2000, 85,000 square kilometers of understory forests burned in the Amazon....

Viewed from space, fires and deforestation near Rondonia, Brazil. Image from NASA

Converting land to agriculture reduces carbon uptake

A press release from the University of Montana: University of Montana researchers examined the impact that converting natural land to cropland has on global vegetation growth, as measured by satellite-derived net primary production, or NPP. They found that measures of terrestrial vegetation growth actually decrease with agricultural conversion, which has important implications for terrestrial carbon storage.

Postdoctoral researcher Bill Smith and UM faculty members Steve Running and Cory Cleveland, along with a former UM postdoctoral researcher and current USGS scientist Sasha Reed, used estimates of agricultural NPP and satellite-derived estimates of natural NPP to evaluate the impact of expanding agricultural land to meet needs for food and fiber. Terrestrial NPP represents the total annual Agricultural lands in Minas Gerais, Brazil. growth of vegetation on the land, which is a critical factor that helps determine how much carbon can be absorbed and stored from the atmosphere.

Their results show that agricultural conversion has reduced that productivity by approximately 7 percent. A small percentage of intensively managed, irrigated or fertilized agricultural land shows an increase in productivity. However, productivity is reduced in 88 percent of agricultural lands globally, with the largest reductions in former tropical forests and savannas.

 “Current forecasts suggest that global food demand will likely double by 2050,” Smith said. “We hope that this research will help to identify strategies that, from a carbon balance perspective, should be avoided due to the potential for severe degradation of global vegetation growth and carbon storage.”...

NASA image of farmland in Minas Gerais, Brazil

Tree roots in the mountains 'acted like a thermostat' for millions of years

EurekAlert via the University of Oxford: For the first time, scientists have discovered how tree roots in the mountains may play an important role in controlling long-term global temperatures. Researchers from Oxford and Sheffield Universities have found that temperatures affect the thickness of the leaf litter and organic soil layers, as well as the rate at which the tree roots grow. In a warmer world, this means that tree roots are more likely to grow into the mineral layer of the soil, breaking down rock into component parts which will eventually combine with carbon dioxide. This process, called weathering, draws carbon dioxide out of the atmosphere and cools the planet. The researchers say this theory suggests that mountainous ecosystems have acted like the Earth's thermostat, addressing the risk of 'catastrophic' overheating or cooling over millions of years.

In their research paper published online in Geophysical Research Letters, the researchers carried out studies in tropical rain forests in Peru, measuring tree roots across different sites of varying altitude – from the warm Amazonian Lowlands to the cooler mountain ranges of the Andes. They measured the growth of the tree roots to 30 cm beneath the surface, every three months over several years. At each of the sites, they also measured the thickness of the organic layer above the soil. This information was then combined with existing data of monthly temperature, humidity, rainfall, and soil moisture in order to calculate the likely breakdown process of the basalt and granite rocks found in the mountain ranges of Peru.

Using this model, based on field data in Peru, the scientists were able to scale up in order to calculate the likely contribution of mountain forests worldwide to global weathering rates. The researchers then calculated the likely amount of carbon to be pulled out of the atmosphere through weathering when the Earth became very hot. They looked at the volcanic eruptions in India 65 million years ago (known as the Deccan traps). The model also allowed them to calculate the weathering process and carbon feedback after the Earth's cooling 45 million years ago, when great mountain ranges like the Andes and the Himalayas were first formed.

The paper suggests that mountainous regions may play a particularly important role in drawing carbon out of the atmosphere because they have abundant volcanic rock which is highly reactive to weathering when it disintegrates...

A 1924 photograph by Eugene Atget of tree roots in St. Cloud