Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Tag Archive: carbon

  1. Managing grazing lands to improve soils and promote climate change adaptation and mitigation: a global synthesis

    Leave a Comment
    • Findings reveal that a variety of management strategies have the potential to improve soil water infiltration rates, with possible benefits for soil carbon as well.
    • Researchers identified a shortage of well-replicated and detailed experiments in all grazing management categories, and call for additional research of both soil water and soil carbon properties for these critical agroecosystems

    DeLonge, M. and Basche, A., 2017. Managing grazing lands to improve soils and promote climate change adaptation and mitigation: a global synthesis. Renewable Agriculture and Food Systems, pp.1-12.

    Abstract

    The potential to improve soils to help farmers and ranchers adapt to and mitigate climate change has generated significant enthusiasm. Within this discussion, grasslands have surfaced as being particularly important, due to their geographic range, their capacity to store substantial quantities of carbon relative to cultivated croplands and their potential role in mitigating droughts and floods. However, leveraging grasslands for climate change mitigation and adaptation will require a better understanding of how farmers and ranchers who rely on them for their livelihoods can improve management and related outcomes.

    To investigate opportunities for such improvements, we conducted a meta-analysis of field experiments that investigated how soil water infiltration rates are affected by a range of management options: adding complexity to grazing patterns, reducing stocking rates or extended rest from grazing. Further, to explore the relationships between observed changes in soil water infiltration and soil carbon, we identified papers that reported data on both metrics. We found that in 81.9% of all cases, responses of infiltration rates to identified management treatments (response ratios) were above zero, with infiltration rates increasing by 59.3 ± 7.3%. Mean response ratios from unique management categories were not significantly different, although the effect of extended rest (67.9 ± 8.5%, n = 140 from 31 experiments) was slightly higher than from reducing stocking rates (42.0 ± 10.8%; n = 63 from 17 experiments) or adding complexity (34.0 ± 14.1%, n =17 from 11 experiments). We did not find a significant effect of several other variables, including treatment duration, mean annual precipitation or soil texture; however, analysis of aridity indices suggested that grazing management may have a slightly larger effect in more humid environments. Within our database, we found that 42% of complexity studies, 41% of stocking rate studies and 29% of extended rest studies also reported at least some measure of soil carbon. Within the subset of cases where both infiltration rates and carbon were reported, response ratios were largely positive for both variables (at least 64% of cases had positive mean response ratios in all management categories).

    Overall, our findings reveal that a variety of management strategies have the potential to improve soil water infiltration rates, with possible benefits for soil carbon as well. However, we identified a shortage of well-replicated and detailed experiments in all grazing management categories, and call for additional research of both soil water and soil carbon properties for these critical agroecosystems.

  2. 20 percent more trees in megacities would mean cleaner air and water, lower carbon and energy use

    Leave a Comment

    18 Jan 2018   read full ScienceDaily article here

    Planting 20 percent more trees in our megacities would double the benefits of urban forests, like pollution reduction, carbon sequestration and energy reduction. The authors of the study say city planners, residents and other stakeholders should start looking within cities for natural resources and conserve the nature in our urban areas by planting more trees….

    T. Endreny, R. Santagata, A. Perna, C. De Stefano, R.F. Rallo, S. Ulgiati. Implementing and managing urban forests: A much needed conservation strategy to increase ecosystem services and urban wellbeing. Ecological Modelling, 2017; 360: 328 DOI: 10.1016/j.ecolmodel.2017.07.016

  3. New estimate of how much humans have transformed the planet; habitat restoration of degraded lands is key to sequestering carbon and reversing climate change

    Leave a Comment
    • Current human use of land is responsible for ~halving the potential storage of carbon by that land. 
    • Through large-scale grazing and other uses of grasslands, as well as forest “management,” humans have subtracted from Earth’s potential carbon sequestration in vegetation an amount equal to deforestation.
    • Earth’s vegetation currently stores around 450 petagrams of carbon [450 billion tons (or gigatons Gt) of carbon or 1665 Gt of CO2e] and in a hypothetical without land use changes, potential vegetation would store around 916 petagrams of carbon, under current climate conditions.
    • Avoiding deforestation is necessary but not enough to reverse climate change.
    • Scenarios that limit global warming to 1.5 or 2 degrees [Celsius] require not only rapid cessation of greenhouse gas emissions but also removal of somewhere between about 100 and 300 billion tons of carbon [or 370 to 1110 billion tons (Gt) of CO2e] from the atmosphere; restoring vegetation is key contribution to controlling climate change
    by Chris Moony Dec 20 2017  see full Washington Post article

    In this age of climate change, we naturally train our attention on all the fossil fuels being combusted for human use — but scientists have long known that what’s happening is also all about the land.

    Just as buried fossil fuels are filled with carbon from ancient plant and animal life, so too are living trees and vegetation on Earth’s surface today. Razing forests or plowing grasslands puts carbon in the atmosphere just like burning fossil fuels does.

    Now, new research provides a surprisingly large estimate of just how consequential our treatment of land surfaces and vegetation has been for the planet and its atmosphere. If true, it’s a finding that could shape not only our response to climate change, but our understanding of ourselves as agents of planetary transformation….

    ….Using a series of detailed maps derived from satellite information and other types of ecological measurements, Erb and his colleagues estimated how much carbon is contained in Earth’s current vegetation. The number is massive: 450 billion tons of carbon, which, if it were to somehow arrive in the atmosphere as carbon dioxide, would amount to over a trillion tons of the gas. (The mass is greater due to the addition of oxygen molecules.)

    But the study also presented an even larger and perhaps more consequential number: 916 billion tons. That’s the amount of carbon, the research calculated, that could reside in the world’s vegetation — so not in the atmosphere — if humans somehow entirely ceased all uses of land and allowed it to return to its natural state. The inference is that current human use of land is responsible for roughly halving the potential storage of carbon by that land….

    …the impact calculation is so large because humans have done far more than just bring about deforestation, which Erb said accounts for about half of the loss of potential vegetation. … “But the other half, in most studies, is completely missing.”…

    …The study found that there are two far-less-recognized components of how humans have subtracted from Earth’s potential vegetation — and that in combination they are just as substantial as deforestation. Those are large-scale grazing and other uses of grasslands, as well as forest “management.” With the latter, many trees and other types of vegetation are subtracted from forests — often the larger and older trees due to logging — but the forests as a whole don’t disappear. They’re just highly thinned out.

    “This effect is quite massive, more massive than we expected actually,” Erb said….

    ….The research means that so-called degraded land — not fully deforested but not “natural” or whole, either — is a phenomenon to be reckoned with.

    “It suggests that the amount of carbon released to the atmosphere from land use is approximately equal to the amount still retained,” said Tom Lovejoy, an ecologist at George Mason University who was not involved in the work. “That means the restoration agenda is even more important than previously thought and highlights the enormous amount of degraded land in the world.”…

    ….“Scenarios that limit global warming to 1.5 or 2 degrees [Celsius] require not only rapid cessation of greenhouse gas emissions but also removal of somewhere between about 100 and 300 billion tons of carbon [or 370 to 1110 billion tons (Gt) of CO2e] from the atmosphere,” Phil Duffy, president of the Woods Hole Research Center, said in an email.

    This paper suggests that restoring vegetation around the world could in principle achieve that,” Duffy continued, noting that if all the potential vegetation were restored it would offset some 50 years of global carbon emissions. While “the full theoretical potential will never be realized in practice … this paper indicates that restoring vegetation could make an extremely important contribution to controlling global climate change.”

    Karl-Heinz Erb et al. Unexpectedly large impact of forest management and grazing on global vegetation biomass. Nature  Dec 2017 doi:10.1038/nature25138
     
     Abstract: Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of
    carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53–58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42–47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.
  4. Healthy soils can play big role in avoiding climate catastrophe- NY Times Op-Ed

    Leave a Comment
    • Regenerative agriculture will be a key part of solving the climate crisis

    DEC. 2, 2017 Read NYTimes article here

    The last great hope of avoiding catastrophic climate change may lie in a substance so commonplace that we typically ignore it or else walk all over it: the soil beneath our feet.

    The earth possesses five major pools of carbon. Of those pools, the atmosphere is already overloaded with the stuff; the oceans are turning acidic as they become saturated with it; the forests are diminishing; and underground fossil fuel reserves are being emptied. That leaves soil as the most likely repository for immense quantities of carbon.

    Now scientists are documenting how sequestering carbon in soil can produce a double dividend: It reduces climate change by extracting carbon from the atmosphere, and it restores the health of degraded soil and increases agricultural yields. Many scientists and farmers believe the emerging understanding of soil’s role in climate stability and agricultural productivity will prompt a paradigm shift in agriculture, triggering the abandonment of conventional practices like tillage, crop residue removal, mono-cropping, excessive grazing and blanket use of chemical fertilizer and pesticide. Even cattle, usually considered climate change culprits because they belch at least 25 gallons of methane a day, are being studied as a potential part of the climate change solution because of their role in naturally fertilizing soil and cycling nutrients.

    The climate change crisis is so far advanced that even drastically cutting greenhouse gas emissions won’t prevent a convulsive future by itself — the amount of greenhouse gases already in the atmosphere ensures dire trouble ahead. The most plausible way out is to combine emission cuts with “negative-emission” or “drawdown” technologies, which pull greenhouse gases out of the atmosphere and into the other pools. Most of these proposed technologies are forms of geoengineering, dubious bets on huge climate manipulations with a high likelihood of disastrous unintended consequences.

    On the other hand, carbon sequestration in soil and vegetation is an effective way to pull carbon from the atmosphere that in some ways is the opposite of geoengineering. Instead of overcoming nature, it reinforces it, promoting the propagation of plant life to return carbon to the soil that was there in the first place — until destructive agricultural practices prompted its release into the atmosphere as carbon dioxide. That process started with the advent of agriculture about 10,000 years ago and accelerated over the last century as industrial farming and ranching rapidly expanded.

    Among the advocates of so-called regenerative agriculture is the climate scientist and activist James Hansen, lead author of a paper published in July that calls for the adoption of “steps to improve soil fertility and increase its carbon content” to ward off “deleterious climate impacts.

    Rattan Lal, the director of the Carbon Management and Sequestration Center at Ohio State, estimates that soil has the potential to sequester carbon at a rate of between 0.9 and 2.6 gigatons per year. That’s a small part of the 10 gigatons a year of current carbon emissions, but it’s still significant. Somewhat reassuringly, some scientists believe the estimate is low.

    ….The techniques that regenerative farmers use vary with soil, climate and crop. They start from the understanding that healthy soil teems with more than a billion microorganisms per teaspoon and the behavior of those organisms facilitates hardy plant life. To fertilize their fields, regenerative farmers use nutrient-rich manure or compost, avoiding as much as possible chemical fertilizers and pesticides, which can kill huge quantities of organic matter and reduce plants’ resilience. They don’t like to till the soil, since tillage increases carbon emissions into the atmosphere. Some farmers combine livestock, cover crops and row crops sequentially on the same field, or plant perennials, shrubs and even trees along with row crops. Leaving soil bare during off-seasons is taboo, since barren soil easily erodes, depleting more carbon from the soil; regenerative farmers instead plant cover crops to capture more carbon and nitrogen from the atmosphere….

    …California began an initiative in 2015 to incorporate soil health into the state’s farm and ranch operations. Some of the pioneering studies showing regenerative agriculture’s benefits have been carried out at the Marin Carbon Project, on a self-proclaimed carbon-farming ranch in the pastoral reaches of Marin County 30 miles northwest of San Francisco. A four-year study there showed that a one-time application of compost caused an increase in plant productivity that has continued ever since, and that the soil’s carbon content grew year after year, at a rate equivalent to the removal from the atmosphere of 1.5 metric tons of carbon dioxide per acre annually.

    Whendee Silver, an ecosystem ecologist at the University of California at Berkeley who is the project’s lead scientist, calculated along with a colleague that if as little as 5 percent of California’s rangelands was coated with one-quarter to one-half inch of compost, the resulting carbon sequestration would be the equivalent of the annual greenhouse emissions of nine million cars. The diversion of green waste from the state’s overcrowded landfills would also prevent it from generating methane, another potent greenhouse gas.

    Some scientists remain skeptical of regenerative agriculture, arguing that its impact will be small or will work only with certain soils. It also faces significant obstacles, such as a scarcity of research funding and the requirements of federal crop insurance, which frequently disqualifies farmers who plant cover crops….

    …. In a region [TX and OK] where rainfall is usually precious, some conventional soil has become so lifeless that it absorbs as little as half an inch of water per hour, Mr. Durham said, while regenerative fields can absorb more than eight inches an hour.

    Mr. Durham’s farmers are learning a lesson that resonates throughout human interactions with the natural world: People reap more benefit from nature when they give up trying to vanquish it and instead see it clearly, as a demanding but indispensable ally. Because of carbon’s climate change connection, we’ve been conditioned to think of it as the enemy, when in fact it’s as vital to life as water. The way to make amends is to put it back in the soil, where it belongs.

     

  5. Timing is key in keeping organic matter in wet cropland soils, new study finds

    Leave a Comment
    • Periodically flooded soils may actually lose organic matter at accelerated rate, a new report suggests.

    November 24, 2017 Iowa State University read full ScienceDaily article here

    ..The study found that timing plays a key role in how well wet soils retain organic matter. While soils with consistently high moisture content do retain organic matter over the long term, soils may actually lose organic matter during shorter spans of flooding. The findings have implications for agricultural fields that are poorly drained or flood for a few weeks of the year before drying out, Hall said. The study also shows that wetlands, thought of as a useful tool for conservation and carbon sequestration, may require consistent flooding to realize environmental benefits from organic matter accumulation….

    …”We found that periodically wet soils don’t necessarily protect organic matter from decomposition and may lead to losses, at least over a timescale of weeks to months,” he said.

    The study drew on research conducted in an ISU laboratory. The researchers took soil samples from a central Iowa cornfield and subjected the sample to various conditions before conducting chemical analyses.

    Hall said future research should widen in scope and include field experiments as well as laboratory-based work. He said he wants to test how various drainage techniques influence organic matter loss as well as pinpoint the length of time required for wet soil to realize environmental benefits….

    Wenjuan Huang, Steven J. Hall. Elevated moisture stimulates carbon loss from mineral soils by releasing protected organic matter. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-01998-z

  6. Deep ocean bacteria discovered to play large role in carbon capture

    Leave a Comment
    • Nitrite-oxidizing bacteria contribute to the capture of carbon dioxide in deep, unlit ocean waters
    November 27, 2017 Bigelow Laboratory for Ocean Sciences
    Marine bacteria that live in the dark depths of the ocean play a newly discovered and significant role in the global carbon cycle, according to a new study.
    The “dark ocean” — everything that lies below 200 meters — makes up 90 percent of the ocean. Very little is known about the microscopic life in this realm and its critical role in transforming carbon dioxide to cell material, proteins, carbohydrates and lipids. This freshly produced organic material can then be consumed by other marine organisms enhancing the productivity of the ocean…
    …”We experimentally demonstrated the major role of nitrite oxidizers in capturing carbon dioxide in the dark ocean and illuminated a group of microbes which has not yet received adequate attention for their impact in the oceanic carbon cycle.”

    Maria G. Pachiadaki, Eva Sintes, Kristin Bergauer, Julia M. Brown, Nicholas R. Record, Brandon K. Swan, Mary Elizabeth Mathyer, Steven J. Hallam, Purificacion Lopez-Garcia, Yoshihiro Takaki, Takuro Nunoura, Tanja Woyke, Gerhard J. Herndl, Ramunas Stepanauskas. Major role of nitrite-oxidizing bacteria in dark ocean carbon fixation. Science, 2017; 358 (6366): 1046 DOI: 10.1126/science.aan8260

  7. Carbon-Free City Handbook- 22 no-regrets actions with immediate results

    Leave a Comment
    • Includes 22 no-regrets actions that nearly every city should take to start the journey to becoming carbon-free. Disciplined application of four primary selection criteria helped cut through hundreds of possibilities to define a focused list for cities. The selected recommendations are:
      • Immediately Actionable: could be launched by city staff within one year
      • Achievable: recently proven and economically viable, with compelling examples of successful city implementation
      • Impactful: leading-edge solutions that either make immediate, significant impact or enable large, long-term carbon reductions
      • Broad Relevance: applicable for most cities globally (population: 100,000+
    • The end result of ambitious 100% goals paired with aggressive action is the same: transformational change mitigating climate impacts. It is about significant, rapid change on a short time frame, rather than slow, incremental change.

    November 11, 2017 Bonn, Germany  read full Rocky Mountain Institute article here

    The Carbon-Free City Handbook (pdf), launched at COP23 [at the UN 2017 climate conference in Bonn, Germany], helps city staff implement climate policies and actions that resolutely place their communities on an aggressive path toward sustainable, low-carbon economies.

    Cities are at the forefront of climate change risk and opportunity. Nearly 600 cities making climate commitments, but they will only get us so far and must be substantiated with on-the-ground solutions that enable cities to make rapid progress toward near-term decarbonization, and put them on a path to full climate-neutrality.

    https://www.rmi.org/wp-content/uploads/2017/11/the-Carbon-Free-City-Handbook-1.0.pdf

     

     

     

     

     

     

  8. Huge carbon sink in soil minerals: New avenue for offsetting rising greenhouse gases

    Leave a Comment

    November 8, 2017  Washington State University read full ScienceDaily article here

    Soil holds more than three times the carbon found in the atmosphere, yet its potential in reducing atmospheric carbon-dioxide levels and mitigating global warming is barely understood. A researcher has discovered that vast amounts of carbon can be stored by soil minerals more than a foot below the surface. The finding could help offset the rising greenhouse-gas emissions helping warm the Earth’s climate…

    …Findings in one of two related papers demonstrate how the right management practices can help trap much of the carbon dioxide that is rapidly warming the planet...

    …Almost three-fourths of all carbon sequestered in the top three feet of the soil is affected by agriculture, grazing or forest management, Kramer and his colleagues report in the Annual Review paper.

    Earlier research by Kramer found that certain farming practices can dramatically increase carbon in the soil. Writing in Nature Communications in 2015, Kramer documented how three farms converted to management-intensive grazing practices raised their carbon levels to those of native forest soils in just six years. While cultivation has decreased soil carbon levels by one-half to two-thirds, the soils he examined had a 75 percent increase in carbon.

    …Knowing more about how soil stores carbon can open the door to new techniques that will entrain carbon deep into the soil while continuing to produce food and fiber….

    1. Marc G. Kramer, Kate Lajtha, Anthony Audfenkampe. Depth trends of soil organic matter C:N and 15N natural abundance controlled by association with minerals. Biogeochemistry, 2017; DOI: 10.1007/s10533-017-0378-x
    2. Robert B. Jackson, Kate Lajtha, Susan E. Crow, Gustaf Hugelius, Marc G. Kramer, Gervasio Piñeiro. The Ecology of Soil Carbon: Pools, Vulnerabilities, and Biotic and Abiotic Controls. Annual Review of Ecology, Evolution, and Systematics, 2017; 48 (1): 419 DOI: 10.1146/annurev-ecolsys-112414-054234
  9. Identifying ‘green’ cattle with lower emissions promises more sustainable farming for multiple benefits

    Leave a Comment

    October 30, 2017 University of Bristol  read full ScienceDaily article here

    Implications of livestock farming on climate change should not be drawn from aggregate statistics, reveals a study based on a new method of carbon footprinting for pasture-based cattle production systems that can assess the impacts of individual animals.

    …The ability to identify “green” cattle within a herd — cattle that produce lower emissions per kilogram of liveweight gain — promises more sustainable farming, they report in the study published today in the Journal of Cleaner Production….

    ..”We agree with the FCRN report that ruminants cannot reverse climate change, even if they are grass-fed,” says Michael Lee, Head of North Wyke and Professor of Sustainable Livestock Systems at Bristol Veterinary School.

    “However, as we discussed in our 2014 article in Nature, pasture-based livestock production systems have a multifaceted role in society — the point acknowledged, but not actively addressed, by the FCRN report….

    G.A. McAuliffe, T. Takahashi, R.J. Orr, P. Harris, M.R.F. Lee. Distributions of emissions intensity for individual beef cattle reared on pasture-based production systems. Journal of Cleaner Production, 2017; DOI: 10.1016/j.jclepro.2017.10.113

  10. The fingerprints of coastal carbon sinks- new technique to measure carbon in coastal wetlands

    Leave a Comment
    • researchers found that using diffuse reflectance spectroscopy, or DRS, normally used on dry soils, may be a more accurate and efficient method compared to more conventional approaches to determine carbon levels in mangrove soils.

    November 1, 2017 American Society of Agronomy read full ScienceDaily article here

    A new study highlights a technique that could be used to accurately measure levels of soil carbon in coastal carbon sinks, such as mangrove forests…

    …In the past, researchers have used the technique — diffuse reflectance spectroscopy, or DRS — to measure carbon in dry soils. “Few studies have tested it in coastal wetland or mangrove soils” …

    …Nóbrega and his colleagues tested DRS on soil samples from three mangrove forests in northeastern Brazil. They found that DRS may be a more accurate and efficient method compared to more conventional approaches to determine carbon levels in mangrove soils.

    …Nóbrega hopes to build a library of soil reflectance fingerprints for mangrove soils throughout the world. He doesn’t want to stop with mangrove soils, though. “Ultimately, we want to expand to other coastal environments, such as saltmarshes, seagrasses, and tidal flats,” he says.

    Eventually, it might be possible to equip a drone with the required sensors. “Then we could obtain vital information without disturbing sensitive ecosystems,” says Nóbrega. “We could monitor carbon levels in large, inaccessible areas.”

    Danilo J. Romero, Gabriel N. Nóbrega, Xosé L. Otero, Tiago O. Ferreira. Diffuse Reflectance Spectroscopy (Vis-Nir-Swir) as a Promising Tool for Blue Carbon Quantification in Mangrove Soils: A Case of Study in Tropical Semiarid Climatic Conditions. Soil Science Society of America Journal, 2017; 0 (0): 0 DOI: 10.2136/sssaj2017.04.0135