Rising global temperatures will have little effect on boreal peatlands

Jeff Sternsland at the University of South Carolina:
To some scientists studying climate change, boreal peatlands are considered a potential ticking time bomb. With huge stores of carbon in peat, the fear is that rising global temperatures could cause the release of massive amounts of CO2 from the peatlands into the atmosphere—essentially creating a greenhouse gas feedback loop.

A new study by researchers at the University of South Carolina and University of California Los Angeles challenges that notion, and demonstrates that the effect of temperature increases on peat storage could be minor. Funded by the National Science Foundation (NSF) and published in “Global Biogeochemical Cycles,” the study instead points to the length of time peat is exposed to oxygen as a much more important factor in how it releases carbon into the atmosphere.

The researchers used the biochemical composition of a peat core collected from the James Bay Lowland in Canada to assess the historical relationship between climate and the extent of peat decomposition. The core is a record of peat accumulation over the last 7,500 years and contains two intervals (the Medieval Climate Anomaly and the Holocene Thermal Maximum) when temperatures were about 2°C warmer than normal, providing a natural analogue for modern warming.

However, peat formed during these warm intervals was not extensively decomposed compared to peat formed during cooler periods. Instead, the most extensive decomposition coincided with drier conditions and longer oxygen exposure time during peat formation. This indicates oxygen exposure time was the primary control on peat decomposition, while temperature was of secondary importance. This was supported by comparing the extent of decomposition along a climate transect in the West Siberian Lowland, Russia. Cores from the northern end of the transect, which experienced longer oxygen exposure times, were more decomposed than cores from the south, which formed under warmer temperatures...

Sunset on the tundra, shot by Paul Gierszewski, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Partially logged rainforests could be emitting more carbon than assumed

Hayley Dunning at Imperial College (London): Global carbon emissions from forests could have been underestimated because calculations have not fully accounted for the dead wood from logging.

Living trees take in carbon dioxide whereas dead and decaying ones release it. Understanding the proportion of both is important for determining whether a large area of forest is a source of carbon dioxide, or a ‘sink’ that helps to absorb carbon dioxide from the atmosphere.

Forestry, agriculture and land-use changes account for nearly 25 per cent of global greenhouse gas emissions, second only to the energy sector. New research led by Imperial College London on partially-logged tropical rainforests suggests that these forests are probably emitting more carbon than assumed, because they contain a high proportion of dead wood. The study, published in Environmental Research Letters, reveals that in these forests dead wood can make up to 64 per cent of the biomass, the biological material found above ground.

In untouched forests, dead wood is created through natural processes and makes up less than 20 per cent of the total aboveground biomass. Previously, when estimating the carbon emissions from logged tropical rainforests, researchers have assumed that when live trees are cut down and moved out of the forest, the amount of dead wood is reduced proportionately.

However, the new research paints a clearer picture of the situation in selectively-logged forests where only high-value trees are removed. It shows that because selective logging leaves behind significant damage and tree debris, dead wood actually accounts for up to 64 per cent of the total aboveground biomass.

“I was surprised by how much of the biomass dead wood accounted for in badly logged forests,” said lead author Dr Marion Pfeifer from the Department of Life Sciences at Imperial. “That such logged forests are not properly accounted for in carbon calculations is a significant factor. It means that a large proportion of forests worldwide are less of a sink and more of a source, especially immediately following logging, as carbon dioxide is released from the dead wood during decomposition.”....

Jami Dwyer took this shot of jungle burned for agriculture. Public domain

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 

Munching bugs thwart eager trees, reducing the carbon sink

University of Wisconsin-Madison News: In a high carbon dioxide world, the trees would come out ahead. Except for the munching bugs. A new study published today [Monday, March 2, 2015] in Nature Plants shows that hungry, plant-eating insects may limit the ability of forests to take up elevated levels of carbon dioxide in the atmosphere, reducing their capacity to slow human-driven climate change.

The finding is significant because climate change models typically fail to consider changes in the activities of insects in the ecosystem, says Richard Lindroth, a professor of ecology at the University of Wisconsin-Madison and the leader of the study. The research suggests it’s time to add insects to the models.

Carbon dioxide typically makes plants grow faster and makes them more efficient in how they use nutrients. But the amount of damage caused by leaf-munching bugs in the study nearly doubled under high carbon dioxide conditions, leading to an estimated 70g of carbon-sequestering biomass lost per meter squared per year.

“This is the first time, at this scale, that insects have been shown to compromise the ability of forests to take up carbon dioxide,” Lindroth says.

In addition, as feeding increased, more nutrients moved from the canopy to the forest floor in the form of insect fecal material and chewed-on leaf scraps, mixing into the soil and likely altering the nutrient profile of the forest....

Photo of a tent caterpillar by Mary A. Jamieson/UW-Madison Department of Entomology

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

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

Soil’s large carbon stores could be freed by increased CO2, plant growth

A press release from Princeton University: An increase in human-made carbon dioxide in the atmosphere could initiate a chain reaction between plants and microorganisms that would unsettle one of the largest carbon reservoirs on the planet — soil.

Researchers based at Princeton University report in the journal Nature Climate Change that the carbon in soil — which contains twice the amount of carbon in all plants and Earth’s atmosphere combined — could become increasin
gly volatile as people add more carbon dioxide to the atmosphere, largely because of increased plant growth. The researchers developed the first computer model to show at a global scale the complex interaction between carbon, plants and soil, which includes numerous bacteria, fungi, minerals and carbon compounds that respond in complex ways to temperature, moisture and the carbon that plants contribute to soil.

Although a greenhouse gas and pollutant, carbon dioxide also supports plant growth. As trees and other vegetation flourish in a carbon dioxide-rich future, their roots could stimulate microbial activity in soil that in turn accelerates the decomposition of soil carbon and its release into the atmosphere as carbon dioxide, the researchers found.

This effect counters current key projections regarding Earth’s future carbon cycle, particularly that greater plant growth could offset carbon dioxide emissions as flora take up more of the gas, said first author Benjamin Sulman, who conducted the modeling work as a postdoctoral researcher at the Princeton Environmental Institute. “You should not count on getting more carbon storage in the soil just because tree growth is increasing,” said Sulman, who is now a postdoctoral researcher at Indiana University.

On the other hand, microbial activity initiated by root growth could lock carbon onto mineral particles and protect it from decomposition, which would increase long-term storage of carbon in soils, the researchers report.

Whether carbon emissions from soil rise or fall, the researchers’ model depicts an intricate soil-carbon system that contrasts starkly with existing models that portray soil as a simple carbon repository, Sulman said. An oversimplified perception of the soil carbon cycle has left scientists with a glaring uncertainty as to whether soil would help mitigate future carbon dioxide levels — or make them worse, Sulman said....

The model projected changes (above) in global soil carbon as a result of root-soil interactions, with blue indicating a greater loss of soil carbon to the atmosphere. (Image by Benjamin Sulman, Princeton Environmental Institute)

NASA study shows 13-year record of drying Amazon caused vegetation declines

A press release from NASA:With global climate models projecting further drying over the Amazon in the future, the potential loss of vegetation and the associated loss of carbon storage may speed up global climate change.

The study was based on a new way to measure the “greenness” of plants and trees using satellites. While one NASA satellite measured up to 25 percent decline in rainfall across two thirds of the Amazon from 2000 to 2012, a set of different satellite instruments observed a 0.8 percent decline in greenness over the Amazon. The study was published on Nov. 11 in Proceedings of the National Academy of Sciences.

While the decline of green vegetation was small, the area affected was not: 2.1 million square miles (5.4 million square kilometers), equivalent to over half the area of the continental United States. The Amazon's tropical forests are one of the largest sinks for atmospheric carbon dioxide on the planet.

"In other words, if greenness declines, this is an indication that less carbon will be removed from the atmosphere. The carbon storage of the Amazon basin is huge, and losing the ability to take up as much carbon could have global implications for climate change," said lead author Thomas Hilker, remote sensing specialist at Oregon State University in Corvallis, Oregon. Plants absorb carbon dioxide as part of photosynthesis, the process by which green plants harvest sunlight. The healthier the plants, the greener the forest.

The Amazon basin stores an estimated 120 billion tons of Earth's carbon – that's about 3 times more carbon than humans release into the atmosphere each year. If vegetation becomes less green, it would absorb less of that carbon dioxide. As a result, more of human emissions would remain in the atmosphere, increasing the greenhouse effect that contributes to global warming and alters Earth's climate...

Popcorn clouds above the Amazon rainforest, August 19, 2009. This type of cloud forms during the dry season, likely from water vapor released by plants during transpiration. Image Credit: NASA's Earth Observatory

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

Arctic sea ice helps remove CO2 from the atmosphere

A press release from the University of Southern Denmark: Due to global warming, larger and larger areas of sea ice melt in the summer and when sea ice  freezes over in the winter it is thinner and more reduced. As the Arctic summers are getting warmer we may see an acceleration of global warming, because reduced sea ice in the Arctic will remove less CO2 from the atmosphere, Danish scientists report. "If our results are representative, then sea ice plays a greater role than expected, and we should take this into account in future global CO2 budgets", says Dorte Haubjerg Søgaard, PhD Fellow, Nordic Center for Earth Evolution, University of Southern Denmark and the Greenland Institute of Natural Resources, Nuuk.

Only recently scientists have realized that sea ice has an impact on the planet's CO2 balance.

"We have long known that the Earth's oceans are able to absorb huge amounts of CO2. But we also thought that this did not apply to ocean areas covered by ice, because the ice was considered impenetrable. However, this is not true: New research shows that sea ice in the Arctic draws large amounts of CO2 from the atmosphere into the ocean", says Dorte Haubjerg Søgaard.

Dorte Haubjerg Søgaard has just completed her studies of sea ice in Greenland. The studies show that sea ice may have a major impact on the global carbon cycle, and that chemical processes have a much greater impact on the sea ice's ability to remove CO2 than biological processes. The research is published as a series of articles in scientific journals.

"The chemical removal of CO2 in sea ice occurs in two phases. First crystals of calcium carbonate are formed in sea ice in winter. During this formation CO2 splits off and is dissolved in a heavy cold brine, which gets squeezed out of the ice and sinks into the deeper parts of the ocean. Calcium carbonate cannot move as freely as CO2 and therefore it stays in the sea ice. In summer, when the sea ice melts, calcium carbonate dissolves, and CO2 is needed for this process. Thus, CO2 gets drawn from the atmosphere into the ocean - and therefore CO2 gets removed from the atmosphere", explains Dorte Haubjerg Søgaard….

Dorte Haubjerg Søgaard from University of Denmark/Grønlands Naturinstitut studies how sea ice removes CO2 from the atmosphere. Photo: Søren Rysgaard, from the University's website 

The good and bad climate news from permafrost melt

John Upton in Climate Central: Carbon inside now-melting permafrost is oozing out, leaving scientists scrambling to figure out just how much of it is ending up in the atmosphere. Whether recent findings from research that attempted to help answer this question are good or bad climate news might depend on whether you see an Arctic river basin as half full of mud — or half empty.

...Frozen soils known as permafrosts can be found across the planet, and they’re concentrated heavily in the Arctic, which has been warming since the 1980s at twice the global rate. Taken together, permafrosts contain more carbon than is already in the atmosphere. Their warming-induced breakdown is helping to fill the atmosphere with greenhouse gases. In a self-feeding cycle, that's fueling the very climatic changes that are causing permafrost to waste away.

“What everyone’s really concerned about is how all this permafrost carbon is going to decompose,” said aquatic geochemist Rose Cory, an assistant professor at the University of Michigan. “If all of that gets turned into carbon dioxide, then we’ll more than double the amount of carbon dioxide in the atmosphere.”

A team of U.S. scientists led by Cory studied Arctic waterways and found that nearly half of the carbon that’s eroding from melting Arctic permafrost is flowing through rivers and lakes and ending up in the seas. Eventually, that sea-bound carbon is likely to be gobbled into aquatic food chains or to settle on ocean floors. The rest is being oxidized in waterways into carbon dioxide, floating into the skies instead of out to sea....

Polar photo ace Brocken Inaglory shot this great image of patterns in permafrost, Wikimedia Commons, under the Creative Commons 3.0 license

Carbon stored in the world’s soils more vulnerable to climate change than expected

A press release from the University of Exeter: The response of soil microbial communities to changes in temperature increases the potential for more carbon dioxide to be released from the world's soils as global temperatures rise, scientists have revealed.

The potential for global warming to stimulate decomposition rates in soils, and thus release large quantities of carbon dioxide to the atmosphere, has long been considered to be one of the potentially most important positive feedbacks to climate change.

However, the results from more recent studies have suggested that responses within microbial communities could greatly reduce, or even eliminate, the potential for soil carbon losses under global warming.

This key idea was tested using soils collected from a thermal gradient from the Arctic to the Amazon rainforest. The results, published in Nature, show that, contrary to expectations, microbial community responses resulted in an overall increase, rather than a decrease, in the effects of temperature on rates of carbon dioxide release from soils.

Dr Kristiina Karhu of the University of Helsinki, and lead author of the paper, said: “Because soils store more than twice as much carbon than the atmosphere, changes in rates of decomposition and carbon dioxide release from soil could be very important. Our findings suggest that warming will increase the activity of soil microbes to a greater extent than was previously expected, which could have implications for future rates of climate change.”...

Some soil in the Netherlands, shot by FotoDutch , Wikimedia Commons, under the Creative Commons 3.0 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

Report supports shutdown of all high seas fisheries

A press release from the University of British Columbia: Fish and aquatic life living in the high seas are more valuable as a carbon sink than as food and should be better protected, according to research from the University of British Columbia.

The study found fish and aquatic life remove 1.5 billion tonnes of carbon dioxide from the atmosphere every year, a service valued at about $148 billion US. This dwarfs the $16 billion US paid for 10 million tonnes of fish caught on the high seas annually.

“Countries around the world are struggling to find cost effective ways to reduce their carbon emissions,” says Rashid Sumaila, director of the UBC Fisheries Economics Research Unit. “We’ve found that the high seas are a natural system that is doing a good job of it for free.”

Sumaila helped calculate the economic value of the carbon stored by life in the high seas by applying prices—which include the benefits of mitigating the costs of climate change–to the annual quantity of carbon absorbed.

The report argues that the high seas—defined as an area more than 200 nautical miles from any coast and outside of national jurisdiction–should be closed to all fishing as only one per cent of fish caught annually are exclusively found there.

“Keeping fish in the high seas gives us more value than catching them,” says Sumaila. “If we lose the life in the high seas, we’ll have to find another way to reduce emissions at a much higher cost.”...

NOAA image of a trawler off the coast of Alaska

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

Vines choke a forest's ability to capture carbon

Terra Daily via SPX: Tropical forests are a sometimes-underappreciated asset in the battle against climate change. They cover seven percent of land surface yet hold more than 30 percent of Earth's terrestrial carbon.

As abandoned agricultural land in the tropics is taken over by forests, scientists expect these new forests to mop up industrial quantities of atmospheric carbon. New research by Smithsonian scientists shows increasingly abundant vines could hamper this potential and may even cause tropical forests to lose carbon.

In the first study to experimentally demonstrate that competition between plants can result in ecosystem-wide losses of forest carbon, scientists working in Panama showed that lianas, or woody vines, can reduce net forest biomass accumulation by nearly 20 percent. Researchers called this estimate "conservative" in findings published this month in Ecology.

"This paper represents the first experimental quantification of the effects of lianas on biomass," said lead author Stefan Schnitzer, a research associate at the Smithsonian Tropical Research Institute and professor at the University of Wisconsin-Milwaukee. "As lianas increase in tropical forests, they will lower the capacity for tropical forests to accumulate carbon."

Previous research by Schnitzer and others demonstrated that lianas are increasing in tropical forests around the globe. No one knows why. Decreased rainfall is one suspect, but lianas, which are generally more drought-tolerant than trees, are increasing in abundance even in rainforests that have not experienced apparent changes in weather patterns....

Lianas in a forest in Kerala, India, shot by Shyamal, public domain 

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

Devastating human impact on the Amazon rainforest revealed

A press release from Lancaster University: The human impact on the Amazon rainforest has been grossly underestimated according to an international team of researchers led by Lancaster University. They found that selective logging and surface wildfires can result in an annual loss of 54 billion tonnes of carbon from the Brazilian Amazon, increasing greenhouse gas emissions. This is equivalent to 40% of the yearly carbon loss from deforestation - when entire forests are chopped down.

This is the largest ever study estimating above and belowground carbon loss from selective logging and ground level forest fires in the tropics, based on data from 70,000 sampled trees and thousands of soil, litter and dead wood samples from 225 sites in the eastern Brazilian Amazon.

The forest degradation often starts with logging of prized trees such as mahogany and ipe. The felling and removal of these large trees often damages dozens of neighbouring trees. Once the forest has been logged, the many gaps in the canopy means it becomes much drier due to exposure to the wind and sun, increasing the risk of wildfires spreading inside the forest. The combination of selective logging and wildfires damages turns primary forests into a thick scrub full of smaller trees and vines, which stores 40% less carbon than undisturbed forests.

So far, climate change policies on the tropics have effectively been focusing on reducing carbon emissions from deforestation only, not accounting for emissions coming from forest degradation.

Lead researcher Dr Erika Berenguer from Lancaster University said: “The impacts of fire and logging in tropical forests have always been largely overlooked by both the scientific community and policy makers who are primarily concerned with deforestation. Yet our results show how these disturbances can severely degrade the forest, with huge amounts of carbon being transferred from plant matter straight into the atmosphere.”...

Logging in Amazonia, shot by Pediboi, Wikimedia Commons, under the Creative Commons 3.0 license