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  • richardmitnick 2:08 pm on April 25, 2016 Permalink | Reply
    Tags: , Carbon studies, ,   

    From The Conversation: “Has China’s coal use peaked? Here’s how to read the tea leaves” 

    Conversation
    The Conversation

    April 12, 2016
    Valerie J. Karplus

    As the largest emitter of carbon dioxide in the world, how much coal China is burning is of global interest.

    In March, the country’s National Bureau of Statistics said the tonnage of coal has fallen for the second year in the row. Indeed, there are reports that China will stop construction of new plants, as the country grapples with overcapacity, and efforts to phase out inefficient and outdated coal plants are expected to continue.

    A sustained reduction in coal, the main fuel used to generate electricity in China, will be good news for the local environment and global climate. But it also raises questions: what is driving the drop? And can we expect this nascent trend to continue?

    It appears many of the forces that led coal use to slow down in recent years are here to stay. Nevertheless, uncertainties abound.

    The future of coal in China will depend on economic factors, including whether alternatives are cheaper and whether a return to high oil prices will encourage production of liquid fuels from coal. Also crucial to coal’s future trajectory are the pace of China’s economic growth and the country’s national climate and air pollution policies.

    Overcapacity

    First, let’s consider how certain we are that the rise in China’s coal use has reversed course. Unpacking that requires understanding the context in which the data is produced.

    China’s national energy statistics are subject to ongoing adjustments. The most recent one, in 2014, revised China’s energy use upward, mainly as a result of adjustments to coal use. The revisions follow the Third National Economic Census, which involved a comprehensive survey of energy use and economic activity that better represent the energy use of small- and medium-sized enterprises.

    There is good reason to believe these revised figures better reflect reality, because they help to explain a well-recognized gap between previously published national totals and the sum of provincial energy statistics, and because these regular revisions capture more sources of energy consumption.

    In short, the latest numbers show China is using more coal and energy than previously thought, but the last two years of data suggest China’s coal use may be peaking earlier than expected.

    1
    China’s latest available energy statistics, based on a more thorough accounting of energy use in China, has the country’s coal use, measured in energy terms, plateauing and declining over the past two years. Valerie Karplus. Data: China Statistical Yearbook 2015 and 2014., Author provided.

    Working from the revised numbers, the observed leveling off of China’s coal use may be both real and sustainable. Efforts to eliminate overcapacity of coal and raise energy efficiency in electric power and heavy industries are biting: in 2014, coal use in electric power fell by 7.8 percent year-on-year, while annual growth in coal consumption in manufacturing fell to 1.6 percent from 4 percent in the previous year, according to data from CEIC.

    The drop in coal use is partly due to structural shifts and partly to good fortune. In electric power, a shift to larger, more efficient power plants and industrial boilers, as well as a reduction in operating hours, has reduced overall coal use.

    The contribution of hydro, wind, solar, nuclear and natural gas in the power generation mix also continues to expand. Abundant rainfall in 2014 allowed the contribution of hydroelectric power to total generation to increase significantly as well.

    Also, the government-led war on air pollution is giving new impetus to clean up or shut down the oldest, dirtiest plants, and bring online new plants with air pollution controls in place.

    These trends, as well as slower economic growth that increasingly driven more by domestic consumption and less by expansion of heavy industry, suggest that coal demand is likely to continue leveling off. This is true even though prices for coal are falling because of overcapacity.

    The impending launch of a national carbon market in 2017 will further penalize coal in several sectors that use it intensively. The carbon market will require heavy emitters to either reduce carbon dioxide emissions by using less coal or purchase credits for emissions reductions from other market participants.

    In this scenario, China’s coal is likely to instead be increasingly exported to other energy-hungry nations less focused on air quality and climate concerns.

    A role for oil prices and air pollution policy

    However, there is at least one scenario in which coal use could easily reverse its downward trend: a return to high oil and natural gas prices.

    Globally, oil prices have plummeted in the past two years, while natural gas prices in China are relatively low for domestic users. High prices for oil and natural gas would make it attractive to convert coal into products that can be used in place of oil, natural gas or chemicals.

    China already has facilities for producing these products, often referred to as synthetic fuels. Plans to substantially expand these activities have been postponed or scuttled due to the lack of an economic rationale.

    But a return to high oil and gas prices would give new life to these projects, which even with a modest price on carbon emissions are likely to be economically viable. The scale of existing synthetic fuels capacity is sufficient to reverse the downward trend in coal use, should it become economic to bring it online.

    2
    Solar, wind and hydro are making a bigger contribution to China’s power generation mix but given the country’s huge energy needs, it is too early to say the country’s carbon emissions are going down. Jason Lee/Reuters

    Meanwhile, China’s carbon and air pollution rules are starting to have an impact on coal use, although the ultimate size of any reduction will depend on resources and incentives to implement policies at the local level.

    Under the National Air Pollution Action Plan, three major urban regions on China’s populous east coast face significant pressure to reduce the concentration of ambient particulate matter pollution by 20-25 percent before 2017, while a 10 percent reduction target is set for the nation as a whole. Cleaning up the air will involve mobilizing an enormous number of local actors on the ground, financing technology upgrades, and introducing policies to reduce pollution-intensive fuels through efficiency and substitution.

    Yet coal use reductions are unlikely to follow in lock step with air pollution reductions. Slower economic growth would be expected to reduce energy demand. But reducing the energy intensity of growth – the amount of energy needed to produce a unit of GDP – will likely become harder over time.

    As economic growth slows, localities will be under pressure to expand opportunities for existing businesses and create new ones. If this pressure leads local officials to resort to expanding energy-intensive activities, such as iron and steel, cement, and heavy manufacturing, to boost local GDP, it will become more difficult to continue reducing China’s coal use per unit of economic output.

    Carbon market in 2017

    Whether coal use continues to decline or goes back up has implications for the timing of China’s emissions peak. At the Paris Climate Summit, China pledged to peak its emissions at latest by 2030, meaning emissions of carbon dioxide would start to fall in absolute terms.

    While it is too early to say that China’s carbon dioxide emissions will continue to fall, it is unlikely that they will rise much further even if the country’s economic aspirations are realized.

    The expansion of hydro and other forms of low or zero carbon energy will help. If the challenges of integrating the energy generated from solar and wind – less predictable sources of energy compared to dispatchable sources such as coal and gas – can be solved, renewable energy that is already installed has the potential to displace significant additional coal use as well, while contributing the reduction in air pollution and carbon dioxide emissions.

    So the answer to the question of whether or not China’s coal use has peaked is: perhaps. China’s coal cap of 4.2 billion tons in 2020 is set roughly 7% higher than the 2013 peak, suggesting that even if the decline reverses course, at least use will not rise much higher. (Note that China’s coal cap sets a limit on coal use on a mass basis, while the above figure reports coal use on an energy basis, and is therefore not directly comparable.)

    This is good news because China’s carbon dioxide emissions have already reached levels in line with previously projected peak levels for 2030, prior to the data revisions. So earlier peaks in both coal use and carbon dioxide emissions now look not only desirable, but possible.

    Sustaining a commitment in China to cultivating cleaner forms of energy production and use will be challenging in the current economic headwinds, but the potential benefits to human health are great, especially in the medium to longer term.

    The country’s national carbon market, planned to launch in 2017, is an important step in the right direction. A sufficiently high and stable carbon price could form the cornerstone of a sustained transition away from coal in favor of clean and renewable energy, developments that would be consistent with existing targets and air quality goals.

    Any transition away from coal in China has the potential to help the world curb its carbon dioxide emissions and to improve domestic air quality – something that will allow us all to breathe a little easier.

    See the full article here .

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    The Conversation US launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 9:11 am on April 21, 2016 Permalink | Reply
    Tags: , , Carbon studies,   

    From BBC: “Pressure grows for price on carbon ahead of UN signing” 

    BBC
    BBC

    4.21.16
    Matt McGrath

    1
    India is calling for a tax on coal to help adaptation to climate change

    A group of world leaders and international finance chiefs has urged the world to rapidly expand the pricing of carbon pollution.

    They argue that more than half of emissions of CO2 should be covered by a carbon price within a decade.

    India has also called on rich countries to put a tax on coal to help poorer nations adapt to climate change.

    These calls came ahead of a UN ceremony where some 155 countries are expected to sign the Paris Climate Agreement.

    Race to ratify the Paris climate deal

    Putting an effective price on carbon has long been the favourite method of most economists in dealing with climate change.

    In 2006 Sir Nicholas Stern’s landmark review of the costs of climate change found that establishing a carbon price was essential to dealing effectively with the problem.

    Cap, trade or tax

    Since then attempts have been made, with mixed success. These have included cap and trade schemes in many parts of the world, where a limit on emissions is established by governments and permits are issued to heavy carbon users. If they cut back on their emissions they can trade the permits on the market.

    Schemes like this have been criticised for being too generous to polluters, often issuing them with free permits. The European Union’s flagship Emissions Trading Scheme almost collapsed because of this practice in recent years.

    Other countries have adopted a more straightforward carbon tax as a means of getting polluters to cut back.

    2

    So far around 12% of the world’s emissions are covered by such schemes. This new coalition of political leaders and financiers says that has to improve significantly if the world is to keep global temperature rises below 2 degrees.

    The group includes the Prime Ministers of Canada and Ethiopia, the Presidents of Chile, France and Mexico, the Chancellor of Germany and the head of the IMF and World Bank.

    They believe that the world can achieve 25% of emissions covered by carbon pricing by 2020 while half the world’s output could be covered by 2025.

    “There is a growing sense of inevitability about putting a price on carbon pollution,” said World Bank President Jim Yong Kim in a statement.

    “Prices for producing renewable energy are falling fast, and putting a price on carbon has the potential to make them even cheaper than fuels that pollute our planet.”

    Without giving too many details, the leaders believe that carbon pricing can be expanded in three ways – by increasing the number of governments putting a price on carbon, by deepening existing carbon pricing programs, and by promoting global cooperation.

    “We should now follow up the Paris Agreement with adequate actions, national policies, investment schemes and regional and international initiatives and partnerships, said Ethiopia’s Prime Minister Dessalegn.

    “I iterate Ethiopia’s commitment to the global efforts to overcome dangerous climate change and ensure sustainable development. We will use every policy instrument, including carbon pricing, which is found to be effective, efficient and fair.”
    Global coal tax?

    India was also keen to promote the idea of carbon pricing before the UN signing ceremony here in New York . They are promoting the idea of a tax on coal.

    The country recently increased its tax on mined coal to $6 a tonne, a significant increase from $1. India’s environment minister Prakasj Javadekar believes the world, especially the wealthier countries, should now follow suit.

    “If they follow India and levy a tax of $5-$6 a tonne on coal production, $100 billion can easily be mobilised,” he said, speaking to news agencies.

    Mr Javadekar said this would be a highly effective way of funding climate adaption in poor countries around the world while incentivising a transition to greener energy sources.

    See the full article here .

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  • richardmitnick 1:28 pm on February 8, 2016 Permalink | Reply
    Tags: , Carbon studies, , , Sea level rise and global warming   

    From LLNL: “Consequences of today’s carbon emissions will linger for thousands of years, study finds” 


    Lawrence Livermore National Laboratory

    Feb. 8, 2016
    Anne M Stark
    stark8@llnl.gov
    925-422-9799

    Carbon emissions
    Carbon emissions in carbon dioxide

    The Earth may suffer irreversible damage that could last tens of thousands of years because of the rate humans are emitting carbon into the atmosphere.

    In a new study in Nature Climate Change, researchers at Oregon State University, Lawrence Livermore National Laboratory and collaborating institutions found that the longer-term impacts of climate change go well past the 21st century.

    “Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years — and some of it will be there for more than 100,000 years,” said Peter Clark, an Oregon State University paleoclimatologist and lead author on the article. “People need to understand that the effects of climate change on the planet won’t go away, at least not for thousands of generations.”

    LLNL’s Benjamin Santer said the focus on climate change at the end of the 21st century needs to be shifted toward a much longer-term perspective.

    “Our greenhouse gas emissions today produce climate-change commitments for many centuries to come,” Santer said. “Today’s actions — or inaction — will have long-term climate consequences for generations of our descendants.”

    “The long-term view sends the chilling message what the real risks and consequences are of the fossil fuel era,” said Thomas Stocker of the University of Bern in Switzerland, who is past co-chair of the Intergovernmental Panel on Climate Change’s (IPCC) Working Group I. “It will commit us to massive adaptation efforts so that for many, dislocation and migration becomes the only option.”

    Sea level rise is one of the most noticeable impacts of global warming, yet its effects are just starting to be seen, according to the article. The latest IPCC report calls for sea level rise of one meter by the year 2100. In the new study, however, the authors look at four different sea level-rise scenarios based on different rates of warming, from a low rate that could only be reached with massive efforts to eliminate fossil fuel use over the next few decades, to a higher rate based on the consumption of half the remaining fossil fuels over the next few centuries.

    With just two degrees (Celsius) warming in the low-end scenario, sea levels are predicted to eventually rise by about 25 meters. With seven degrees warming at the high-end scenario, the rise is estimated at 50 meters, although over a period of several centuries to millennia.

    “It takes sea level rise a very long time to react — on the order of centuries,” Clark said. “It’s like heating a pot of water on the stove; it doesn’t boil for quite a while after the heat is turned on — but then it will continue to boil as long as the heat persists. Once carbon is in the atmosphere, it will stay there for tens or hundreds of thousands of years, and the warming, as well as the higher seas, will remain.”

    For the low-end scenario, an estimated 122 countries have at least 10 percent of their population in areas that will be directly affected by rising sea levels, and some 1.3 billion people — or 20 percent of the global population — may be directly affected. The impacts become greater as the warming and sea level rise increases.

    The new paper makes the fundamental point that considering the long time scales of the carbon cycle and of climate change means that reducing emissions slightly or even significantly is not sufficient. “To spare future generations from the worst impacts of climate change, the target must be zero — or even negative carbon emissions — as soon as possible,” Clark said.

    The researchers’ work was supported by the U.S. National Science Foundation, the U.S. Department of Energy, the Natural Sciences and Engineering Research Council of Canada, the German Science Foundation and the Swiss National Science Foundation.

    See the full article here .

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  • richardmitnick 11:50 am on January 8, 2016 Permalink | Reply
    Tags: , Carbon studies, , Rain forest research   

    From Princeton: “In rainforests, battle for sunlight shapes forest structure” 

    Princeton University
    Princeton University

    January 8, 2016
    Catherine Zandonella, Office of the Dean for Research

    New finding helps explain rainforests’ influence on global climate

    1
    Rainforests around the globe have a remarkably consistent pattern of tree sizes. Now researchers have found that the reason for this structure has to do with the competition for sunlight after a large tree falls and leaves an opening in the canopy. Image credit: Caroline Farrior

    Despite their diversity, the structure of most tropical rainforests is highly predictable. Scientists have described the various sizes of the trees by a simple mathematical relationship called a power law.

    In a new study using data from a rainforest in Panama, researchers determined that competition for sunlight is the underlying cause of this common structure, which is observed in rainforests around the globe despite differences in plant species and geography. The new finding can be used in climate simulations to predict how rainforests absorb excess carbon dioxide from the atmosphere.

    The study, conducted by researchers at Princeton University, the National Institute for Mathematical and Biological Synthesis, the Smithsonian Tropical Research Institute and collaborating institutions, was published Jan. 8 in the journal Science. The investigation was supported in large part by the National Science Foundation.

    2
    After a large tree falls, many small individuals are able to grow due to an increase in available sunlight (T=1). Once they have grown to touch one another (T=2), they begin to overtop one another and leave individuals behind in the understory (T=3). Image courtesy of Caroline Farrior.

    The researchers found that the rainforest structure stems from what happens after a tall tree falls and creates a gap in the canopy. The gap enables sunlight to reach the forest floor and fuel the rapid growth of small trees. Over time, the trees’ crowns grow to fill the gap until the point where not all of the trees can fit in the sunlit patch. Some will be left behind in the shade of their competitors.

    “This process of moving from fast growth in the sun to slow growth in the shade sets up this characteristic size structure that is common across tropical rainforests, despite the differences in their environments,” said Caroline Farrior, first author of the study who is a postdoctoral fellow at the National Institute for Mathematical and Biological Synthesis and will soon be an assistant professor of integrative biology at the University of Texas-Austin.

    Farrior, who earned her Ph.D. in ecology and evolutionary biology from Princeton University in 2012, completed most of the work as a postdoctoral researcher in the Princeton Environmental Institute with co-author Stephen Pacala, Princeton’s Frederick D. Petrie Professor in Ecology and Evolutionary Biology.


    download mp4 video here.
    (View a video interview with Dr. Farrior courtesy of the National Institute for Mathematical and Biological Synthesis.)

    “Rainforests store about twice as much carbon as other forests,” Pacala said. “About half of that is due to huge trees, but the other half is all that stuff in the middle. It is not possible to build an accurate climate model without getting that right.”

    To gain an understanding of how rainforests grow, Farrior and colleagues analyzed decades of tree census data from a 50-hectare plot on Barro Colorado Island in the Panama Canal. From these data, they identified the mechanism most important in driving the observed size structure in tropical rainforests.

    “With this new understanding of tropical forests, we can go on to build better models, we can make more accurate estimates of the carbon storage that’s currently in tropical forests, and we can go on to more accurately predict the pace of climate change in the future,” Farrior said.

    The research included work by Stephanie Bohlman, an assistant professor at the University of Florida and a research associate at the Smithsonian Tropical Research Institute (STRI), and Stephen Hubbell, a staff scientist at STRI.

    The study was supported by Princeton’s Carbon Mitigation Initiative and the National Institute for Mathematical and Biological Synthesis (NSF grant no. DBI-1300426) at the University of Tennessee-Knoxville. The Barro Colorado Island forest dynamics research project was founded by Stephen Hubbell, Robin Foster and Richard Condit of STRI.

    The study, “Dominance of the suppressed: Power-law size structure in tropical forests,” by Caroline Farrior, Stephanie Bohlman, Stephen Hubbell and Stephen Pacala, appeared in the journal Science on Jan. 8, 2016.

    See the full article here .

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    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 12:21 pm on November 12, 2015 Permalink | Reply
    Tags: , Carbon studies, ,   

    From Goddard: “A Breathing Planet, Off Balance” 

    NASA Goddard Banner
    Goddard Space Flight Center

    Nov. 12, 2015
    Kate Ramsayer
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Carol Rasmussen
    NASA’s Earth Science News Team

    Earth’s oceans and land cover are doing us a favor. As people burn fossil fuels and clear forests, only half of the carbon dioxide released stays in the atmosphere, warming and altering Earth’s climate. The other half is removed from the air by the planet’s vegetation ecosystems and oceans.

    As carbon dioxide levels in the atmosphere continue their rapid, man-made rise past levels not seen for hundreds of thousands of years, NASA scientists and others are confronted with an important question for the future of our planet: How long can this balancing act continue? And if forests, other vegetation and the ocean cannot continue to absorb as much or more of our carbon emissions, what does that mean for the pace of climate change in the coming century?

    These questions are a major priority for NASA’s Earth science research program, and the agency is preparing to ramp up its field studies, satellite monitoring and computer modeling to help answer them. Carbon is a fundamental element of life on Earth, but the increasing amount of carbon in the atmosphere — in the form of carbon dioxide and methane molecules — is also the primary element driving our warming climate. Scientists are studying how carbon moves through Earth’s atmosphere, land and ocean with an array of tools, including a new dataset of the ebbs and flows of carbon in the air.

    “Today and for the past 50 to 100 years, the oceans and land biosphere have consistently taken up about half of human emissions,” said Dave Schimel of NASA’s Jet Propulsion Laboratory, Pasadena, California. “If that were to change, the effect of fossil emissions on climate would also change. We don’t understand that number, and we don’t know how it will change in the future.”


    Earth’s land and ocean currently absorb about half of all carbon dioxide emissions from the burning of fossil fuels, but it’s uncertain whether the planet can keep this up in the future. NASA’s Earth science program works to improve our understanding of how carbon absorption and emission processes work in nature and how they could change in a warming world with increasing levels of emissions from human activities.Credits: NASA’s Jet Propulsion Laboratory.
    download mp4 video here.

    So researchers at NASA are tackling the questions from a number of angles. They’re monitoring land, atmosphere and oceans with airborne and satellite sensors and digging into the first results from a new satellite observatory measuring carbon dioxide. And they’re pulling all the information we have into supercomputer simulations to understand how our Earth responds to changes in carbon emissions.

    “There are all these amazing data sets, but none of them quite give us the entire carbon story,” said Lesley Ott, an atmospheric scientist with the Global Modeling and Assimilation Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The models help us tie all the observations together to get at how atmospheric carbon is varying and changing, but we still have a lot of work left to do to understand how carbon moves among the land, oceans and atmosphere.”

    Carbon on the move

    Carbon naturally cycles through Earth’s environments. Trees and other plants take up carbon dioxide and turn it into the building blocks of roots, stems and leaves. Some of that carbon stays in the soil as the vegetation dies and gets buried. Some is released back into the atmosphere as carbon dioxide through plant respiration, and both carbon dioxide and methane — another potent, carbon-based greenhouse gas — can be released through decomposition, land clearing and wildfire. The ocean absorbs carbon dioxide from the atmosphere, and the tiny water-dwelling plants called phytoplankton take up the gas as well. Over many millennia, the pace of carbon cycling is governed by volcanic emissions and weathering of rocks.

    For most of human history, carbon has been in a more-or-less steady cycle. This cycle has been thrown off balance as people burn fossil fuels — carbon that has been long buried underground as oil, gas and coal — and as forests are cleared and soils are turned for agriculture. All of these contribute to increasing carbon emissions. While the amount of carbon dioxide emissions that ecosystems absorb from the atmosphere each year varies quite a bit, the fraction in the long run has averaged out to about half.

    More carbon dioxide and methane in the air means warmer global temperatures. Warmer temperatures can disrupt some ecosystems and impact their ability to absorb more and more carbon. An even more imbalanced carbon cycle will cause greater variability and consequences that are not yet fully understood.

    NASA’s newest tool in tackling the complex question of carbon ebbs and flows is the Orbiting Carbon Observatory-2, or OCO-2.

    NASA Orbiting Carbon Observatory 2
    OCO-2

    Launched in July 2014, the mission measures how much carbon dioxide is in the atmosphere near the planet’s surface. With that dataset, researchers can better begin to characterize where carbon is being emitted and absorbed and over what timescales. Mission scientists recently analyzed OCO-2’s first year of data, and saw the expected decreases in atmospheric carbon dioxide in the Northern Hemisphere’s summer, as plants undergo photosynthesis. They saw upticks in the greenhouse gas over power plants and megacities, and over areas where people clear forests for agricultural use.

    “The new, exciting thing from my perspective is we have more than 100,000 measurements each day of carbon dioxide in the atmosphere,” said Annmarie Eldering, OCO-2 deputy project scientist at JPL. “Not only do we have a lot of measurements, but they tell us a lot. We can see a change [in atmospheric carbon] of one-quarter of 1 percent from space. Armed now with this pile of data, we can start to investigate more fully this question of sources and sinks and how different parts of the world contribute to these processes.”


    The Orbiting Carbon Observatory-2 satellite is providing NASA’s first detailed, global measurements of carbon dioxide in the atmosphere at the Earth’s surface. OCO-2 recently released its first full year of data — critical to analyzing the annual cycle carbon dioxide concentrations in the atmosphere.Credits: NASA/JPL-Caltech
    download mp4 video here.

    Plants and ocean lend a hand

    Terrestrial plants — from towering Douglas firs to moss growing on rocks — take up carbon dioxide from the atmosphere during photosynthesis, processing it into carbon-containing leaves, stems, branches and more.

    “The land helps to mitigate something like a quarter of the carbon dioxide emissions,” said Jeffrey Masek, chief of the biospheric sciences laboratory at NASA Goddard. “The question is: What will happen in the future? Can we count on this to continue? Or are land processes going to saturate, in which case we’d see our atmospheric carbon dioxide concentration start to increase much more rapidly.”

    Monitoring photosynthesis is one way for scientists to study vegetation health and growth in an atmosphere with increasing carbon dioxide. Even though photosynthesis is a process occurring at the microscopic scale on the land and in the ocean, scientists have found the best way to monitor it globally is by satellite.

    “If it weren’t for satellites, we would have very little understanding of the biological activity of the entire Earth,” said Josh Fisher, a climate scientist at JPL. “We know from our field studies about how different ecosystems [vary], but we don’t know how robust or representative our studies are at the global scale.”

    The Landsat missions and the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua spacecraft allow researchers to study the greenness of vegetation as a proxy for photosynthesis, and therefore carbon dioxide uptake, across the globe.

    NASA Landsat 8
    Landsat 8

    NASA MODIS
    MODIS

    NASA Terra satellite
    Terra

    NASA Aqua satellite
    Aqua

    Scientists are also using OCO-2 to take a big-picture look at these small-scale processes, capturing the faint fluorescence given off by terrestrial plants during photosynthesis, Eldering said. With fluorescence, scientists have a new way to observe how active – or not – these green ecosystems are.


    Animation showing the 12-month cycle of all plant life on Earth — whether on land or in the ocean. Rather than showing a specific year, the animation shows an average yearly cycle by combining data from many satellite instruments and averaging them over multiple years. Credits: NASA’s Goddard Space Flight Center
    download mp4 video here.

    Forests are one of the major carbon sinks, which are areas that absorb large amounts of carbon dioxide from the atmosphere, storing it for decades in trunks and roots. Satellite observations have illustrated how green plants have expanded their territory in North America, as warmer temperatures allow them to grow farther north. Height-measuring instruments, like radars and lidars, add a third dimension to the land cover information, allowing researchers to estimate how much material — and therefore how much carbon — is stored in a forest. NASA has plans to launch satellites as well as put a sensor on the International Space Station (ISS) to measure this third dimension of forest structure and improve estimates of how much carbon is stored in large forests.

    NASA has targeted a variety of future field campaigns, satellites and ISS sensors to improve our understanding of how much carbon is being stored in terrestrial ecosystems and how this could change as patterns of drought, fire and forest structure itself shift in a changing climate.

    More carbon in the atmosphere can act as a fertilizer and give vegetation a boost, increasing the storage of the greenhouse gas at least temporarily. But any increased plant growth due to more carbon dioxide in the air can’t continue forever, researchers say. Eventually, the vegetation will run out of water or other nutrients necessary for enhanced growth, while changes in temperature and rainfall could also alter growing conditions. Without these essentials, vegetation can’t keep taking up increasing amounts of greenhouse gases from human-caused emissions.

    In some regions, forests are releasing more carbon than they’re storing. Satellite images have also documented the transition of green, healthy forests through land clearing and events like wildfires and insect infestations, which are increasing in drought-stressed environments. Droughts themselves slow down the growth of vegetation, slowing down the uptake of carbon in regions such as the Amazon. This can flip the balance for forests and other ecosystems – from an overall absorber of carbon to an overall emitter of the greenhouse gas. While natural climate variability may cause such year-to-year changes, scientists are concerned that climate change could turn forests into sources of carbon on a regular or even annual basis.

    Ocean scientists are facing similar questions about carbon. The ocean water itself absorbs carbon dioxide from fossil fuel emissions. Doing so, however, changes the chemistry of seawater. As surface water in the ocean continues to warm, uptake of carbon dioxide will slow down.

    Oceans also contain carbon in the form of plants and animals, including phytoplankton — microscopic plants that take up carbon dioxide through photosynthesis, just like their larger, land-based cousins. Phytoplankton form the base of the ocean food web, and those that survive being eaten by zooplankton will die, sinking to the bottom of the ocean — taking their carbon stores with them to be decomposed. Changes to ocean chemistry and circulation due to climate change may alter this biological carbon pump, potentially triggering a release of the carbon stored deep in ocean sediments.

    In the North Atlantic the distribution of phytoplankton species is changing due to warming waters, notes Carlos Del Castillo, ocean ecology laboratory chief at Goddard. A different mix of phytoplankton species will take up different amounts of carbon dioxide — which could result in even further changes to the ocean’s carbon cycle. “It’s a cycle, which we hope is not a vicious one,” Del Castillo said.

    Getting a global view

    To get a more complete picture of this global carbon cycle, NASA scientists are combining many different approaches to studying the land, ocean and atmosphere. They use NASA’s wealth of data on carbon dioxide in the atmosphere with weather and climate models to monitor every response of Earth processes to the increasing burden of carbon dioxide.


    Animation of carbon dioxide released from two different sources: fires (biomass burning) and massive urban centers known as megacities. The animation covers a five day period in June 2006. The model is based on real emission data and is then set to run so that scientists can observe how the greenhouse gas behaves once it has been emitted. Credits: Global Modeling and Assimilation Office, NASA’s Goddard Space Flight Center.
    download mp4 video here.

    “You’ve got all these little individual sources of change — the insects, the fire, agriculture expanding and other land use — all this stuff flickering around on the ground, varying from year to year, over decades. And then you’ve got these integrated observations of the atmosphere,” Masek said. “You need models that incorporate these processes — all of them. And then if that model is reasonable, we should be able to predict what the atmospheric carbon dioxide looks like. It’s a tough job.”

    With the supercomputers at NASA, scientists take in all the information they can — from all the Earth science fields they can. They program computer models to take all these inputs and try to determine whether the land and oceans will keep giving people an assist.

    “Ultimately the goal of all of this work is to be able to predict what’s going to happen with the carbon cycle,” Ott said. “How much carbon is going to be taken up by the land and ocean? We need to know how that’s going to change in the future.”

    By coming at the problem from multiple vantage points, using a range of measurements and tools, scientists are strengthening the models to give us a better picture of what our carbon-directed climate will look like in the coming years and beyond.

    See the full article here .

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

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  • richardmitnick 1:55 pm on October 1, 2015 Permalink | Reply
    Tags: , Carbon studies,   

    From New Scientist: “First digital map of ocean sediments reveals weaker carbon sink” 

    NewScientist

    New Scientist

    30 September 2015
    Michael Slezak

    1
    (Image: Adriana Dutkiewicz et al./University of Sydney)

    The first global digital map of the ocean floor sediments (shown above) shows we have little clue about how the world’s biggest carbon sink works.

    About half the carbon emitted into the atmosphere by human activity ends up in the ocean. It dissolves into the surface water, where it is taken up by phytoplankton during photosynthesis.

    “Once they die their remains sink to the bottom and they lock away the carbon,” says Adriana Dutkiewicz at the University of Sydney in Australia. Or at least, that’s what people thought.

    Dutkiewicz has now shown that this process seems to depend on water temperature ¬and salinity – something her team discovered when they digitally mapped the seafloor.

    Previous maps of seafloor sediments were drawn by hand, and the last one was completed in the 1970s. So Dutkiewicz and colleagues looked at sediment descriptions and samples taken by scientific cruises from as long ago as the 1950s. From more than 200,000 data points, they focused on the 15,000 highest quality ones, and used a computer model to turn them into a detailed map of the world’s ocean sediments.
    Blotchy sediment

    The map threw up surprises. It found there is 30 per cent more clay on the seafloor than previously thought, and 25 per cent less of a sediment called diatom ooze – the dead remains of a type of phytoplankton called diatoms.

    And what researchers thought were continuous belts of different sediment types turned out to be separate pockets, blotched around the ocean floor.

    Dutkiewicz then compared the map with data related to the temperature and salinity of the ocean surface, as well as regions with regular large blooms of diatoms – the most common type of phytoplankton.

    “The map demonstrates that the diatoms on the seafloor don’t correspond to seasonal blooms on the surface,” says Dutkiewicz. Instead, the amount that makes it to the bottom depends on the surface water having a low salinity and temperatures of between 0.9 and 5.7°C, but high concentrations of nutrients.

    Without these surface conditions, fewer diatoms make it to the bottom. “We know they come from the surface, but they suffer some sort of fate before they get to the seafloor. They are not preserved,” she says. “They get recycled in the upper surface somewhere.”

    And that means that rather than being locked away on the ocean floor for millennia, the carbon re-enters the atmosphere sooner. But exactly how long before it makes it back into the atmosphere is unknown.
    Puzzle piece

    “It’s one piece of the puzzle,” says Philip Boyd at the University of Tasmania. “It’s possible that there’s a large proportion of material that could sink below 300 or 400 metres and that would take the carbon out of circulation for decades or centuries.”

    Next, Dutkiewicz plans to look at the relationship between temperature and diatom accumulation over tens of millions of years by drilling cores of ocean sediment.

    But the fact that what makes it to the bottom seems to depend on temperature is a worry in the face of soaring temperatures, says Dutkiewicz.

    In the longer term, things are even grimmer since diatoms only live in cold water. “With warming, the diatoms will be replaced with small phytoplankton that produce less oxygen and have less mass so deposit less carbon on the seafloor,” she says.

    Journal reference: Geology, DOI: 10.1130/G36883.1

    See the full article here .

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  • richardmitnick 7:40 pm on September 6, 2015 Permalink | Reply
    Tags: , Carbon studies,   

    From Princeton: “How to Curb Emissions? Put a Price on Carbon” 

    Princeton University
    Princeton University

    Princeton Woodrow Wilson School

    Sep 3, 2015
    B. Rose Huber | 609-258-0157

    1
    Literally putting a price on carbon pollution and other greenhouse gasses is the best approach for nurturing the rapid growth of renewable energy and reducing emissions, according to an article published in Nature. (Photo credit: Environmental Defense Fund)

    Literally putting a price on carbon pollution and other greenhouse gasses is the best approach for nurturing the rapid growth of renewable energy and reducing emissions.

    While prospects for a comprehensive carbon price are dim, especially in the U.S., many other policy approaches can spur the renewables revolution, according to a new policy article published in Nature.

    The current price of carbon – which is below zero, once fossil-fuel subsidies are taken into account – is far too low given the hidden environmental, health and societal costs of burning coal and oil.

    The authors – which include Princeton University’s Michael Oppenheimer, Albert G. Milbank Professor of Geosciences and International Affairs at the Woodrow Wilson School of Public and International Affairs – urge policymakers to implement a range of policies until the time that a carbon price becomes politically realistic.

    The article, whose lead author is Gernot Wagner, senior economist at the Environmental Defense Fund, urges modernizing and opening up access to power grids for renewable sources like solar and wind energy (similar to the access fossil fuel sources enjoy), and subsidizing key technologies, particularly for energy storage. Additionally, investments must be made that support research and development related to low-carbon energy technologies.

    “The current inadequacy of carbon pricing stems from a catch-22,” the authors write. “Policymakers are more likely to price carbon appropriately if it is cheaper to move onto a low-carbon path. But reducing the cost of renewable energies requires investment, and thus a carbon price.”

    While some obstacles regarding low-carbon energy are technological, many are policy-driven, the authors write. Current policies were set with the fossil-fuel industry in mind, but the same principle could apply with the emerging renewable energy technologies as well.

    The authors point toward Germany and China as examples. Germany’s Renewable Energy Sources Act guaranteed 20 years of grid access and fixed prices for solar- and wind-power producers. Meanwhile, in China, climate, energy and industrial policies have boosted the manufacturing scale of renewable technologies.

    But despite these efforts, many countries still use coal and natural gas as their main source of electricity. Likewise, many forms of bioenergy actually increase net emissions rather than reduce them.

    To this end, the authors suggest the following for policymakers and governments:

    Check that all climate-change interventions pass a benefit-cost test (taking environmental, health and societal costs into account);
    Ensure policies related to renewable energy ease the way toward a national carbon cap or tax;
    Open up access to electricity grids for renewables and break up any non-competitive arrangements;
    Support the modernization of power grids to facilitate adoption of new renewable energy sources; and
    View the energy sector in its entirety since transportation may become increasingly dependent on electricity.

    “Ambitious renewables policies should be followed by strengthened climate policies,” the authors conclude. “These are the sorts of pieces that need to come together to deepen solar and wind penetration levels and achieve the ‘holy grail’ of climate policy: an effective carbon price.”

    Co-authors include Tomas Kaberger, professor of industrial energy policy at Chalmers University of Technology in Gothenburg, Sweden; Susanna Olai, an environmental economist at the University of Gothenburg, Sweden; Katherine Rittenhouse, an economic analyst at the Environmental Defense Fund in Boston, Massachusetts; and Thomas Sterner, professor of environmental economics at the University of Gothenburg.

    The article, “Push renewables to spur carbon pricing,” was published in the Sept. 3, 2015, issue of Nature.

    See the full article here .

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    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 2:59 pm on September 3, 2015 Permalink | Reply
    Tags: , Carbon studies,   

    From SUNY Buffalo: “Filtering the carbon from coal” 

    SUNY Buffalo

    SUNY Buffalo

    UB-led team awarded $1.9 million federal grant to insert palladium nanoparticles into membrane that removes greenhouse gases from the fossil fuel

    1
    Credit: Petteri Sulonen via Wikipedia Commons.

    September 3, 2015
    Cory Nealon

    Despite gains by natural gas, wind and solar, coal remains the top electricity producer in the United States.

    Accordingly, interest is strong in developing technology that curbs unwanted effects, such as greenhouse gas emissions, that result from coal’s combustion.

    To address the matter, the U.S. Department of Energy has awarded a $1.9 million grant to a research team led by the University at Buffalo. The researchers will develop a membrane to remove carbon dioxide, which makes up the vast majority of greenhouse gas emissions, from gasified coal before its combustion.

    “The idea is to decarbonize coal before burning it,” said Haiqing Lin, PhD, the grant’s principal investigator and an assistant professor in the Department of Chemical and Biological Engineering at UB’s School of Engineering and Applied Sciences.

    2
    Haiqing Lin, assistant professor of chemical and biological engineering, University at Buffalo. No image credit.

    The grant is one of 16 announced last month by the energy department’s National Energy Testing Laboratory.

    Lin will work with UB Distinguished Professor Mark T. Swihart, PhD, who serves as executive director of the New York State Center of Excellence in Materials Informatics. Also working on the project are Helios-NRG, LLC of Amherst, New York; Membrane Technology and Research, Inc. of Newark, California; and the National Carbon Capture Center in Wilsonville, Alabama.

    “We are pleased to be working with UB on developing this exciting new technology which has the potential to make a step change in the economics of carbon capture from fossil-fueled power plants, thereby mitigating the nation’s emissions of greenhouse gases,” said Ravi Prasad, president at Helios, one of roughly two dozen high-tech startup companies in the UB Technology Incubator, which is administered by the university’s Office of Science, Technology Transfer and Economic Outreach (STOR).

    While coal accounted for 39 percent of the nation’s electricity in 2014, it contributed 77 percent of the electricity sector’s carbon dioxide emissions, according to U.S. Energy Information Administration data. Because of coal’s abundance in the U.S. and abroad, researchers are exploring ways to capture, utilize and sequester carbon dioxide from the fossil fuel, a concept more commonly known as “clean coal.”

    One way involves turning coal into a gas by reacting the fossil fuel at high temperatures with oxygen or steam. The result is a synthetic gas (syngas), containing mainly hydrogen and carbon dioxide, which can be used, among other things, to generate electricity.

    Technology exists to remove the majority of carbon dioxide from syngas; however, the process makes it expensive compared to electricity derived from natural gas and other sources. The idea of using a membrane is appealing, Lin said, because it’s passive, and potentially more energy-efficient and less costly compared to other technologies.

    The team will develop and test a polymer-based membrane outfitted with palladium-based nanoparticles. The polymers act as a filter, largely preventing the passage of carbon dioxide, while the palladium acts as a bridge that enables hydrogen gas to more easily pass through the membrane.

    Theoretically, the hydrogen gas would pass through the membrane and then be burned, which in turn would power turbines. Meantime, the carbon dioxide could be geologically sequestered, used to create chemicals or pumped underground for enhanced oil recovery.

    See the full article here.

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    SUNY Buffalo Campus

    UB is a premier, research-intensive public university and a member of the Association of American Universities. As the largest, most comprehensive institution in the 64-campus State University of New York system, our research, creative activity and people positively impact the world.

     
  • richardmitnick 2:52 pm on August 19, 2015 Permalink | Reply
    Tags: , Carbon studies, ,   

    From Nature: “China’s carbon emissions overestimated” 

    Nature Mag
    Nature

    19 August 2015
    Jeff Tollefson

    1
    China’s cement industry may produce less carbon than was thought. Xiezhengyi/Cpressphoto/Corbis

    China’s carbon emissions may be significantly lower than previously thought — about 14% less in 2013 than estimated by the Chinese government and others, according to research published this week in Nature (Z. Liu et al. Nature 524, 335–338; 2015). The analysis draws on data from more than 4,200 Chinese mines — including new measurements of the energy content of coal — among other sources.

    “At the beginning of the project we thought that the emissions might be higher” than existing estimates, says Zhu Liu, an ecologist at Harvard University in Cambridge, Massachusetts, and lead author of the study. “We were very surprised.”

    His team’s findings do not unseat China from its position as the world’s largest emitter of carbon dioxide. Even when the lower estimate is taken into account, China’s carbon output for 2013 is still more than two-thirds higher than that of the United States, the second-largest emitter. But the study underscores long-standing uncertainties in the methods with which scientists calculate the emissions of individual nations, and how much carbon cycles through the atmosphere and into oceans and ecosystems. For comparison, the cumulative reduction in Chinese emissions outlined in the study — roughly 2.9 billion tonnes from 2000 to 2013 — is larger than the estimated amount of carbon that the world’s forests pulled out of the atmosphere from 1990 to 2007.

    That presents a problem for researchers who study the carbon cycle. “We can easily go back and retroactively adjust Chinese carbon-emission estimates,” says Ashley Ballantyne, a climate scientist at the University of Montana in Missoula. “Unfortunately, we cannot go back and adjust all the previous studies on the global carbon cycle and their conclusions based on the previously biased emission estimates.”

    The Chinese government releases data on energy consumption and production at the provincial and national levels, but those statistics often conflict with each other, and are revised frequently. Liu and his team analysed government data on energy production and on exports and imports of coal, oil and gas. They found that China’s fossil-fuel use was 10% above the official government estimate, but that the country’s overall emissions were lower once China’s reliance on low-quality coal from domestic mines was taken into account. This is because lower-quality coal contains less carbon than higher-quality deposits, so burning it produces less energy and less heat-trapping CO2.

    The team says that its estimate for how much CO2 will be produced by burning Chinese coal is around 40% less per unit than the figures adopted by the Intergovernmental Panel on Climate Change. And the team calculates that emissions from cement production, a coal-fuelled process that is a major contributor to global emissions, are 45% below existing estimates.

    The coal measurements were collected from mine reports and from a project sponsored by the Chinese Academy of Sciences that assesses the country’s cumulative carbon emissions and carbon uptake by ecosystems across China. Liu says that the quality of Chinese coal is likely to be getting worse as the country burns through its best reserves.

    “This is probably the best available estimate of emissions from coal burning in China, and that is an important contribution,” says Gregg Marland, a geologist at Appalachian State University in Boone, North Carolina, and a co-author of the study. But he adds that the revised figure is within the range of uncertainty reported in existing inventories.

    And it may need to be increased as the Chinese government releases further energy data, says Glen Peters, a climate-policy researcher at the Center for International Climate and Environ­mental Research in Oslo. Although China said in February that its coal consumption had dropped between 2013 and 2014, he notes, the government has since increased its cumulative estimate of coal consumption over the past decade by 12–14%. Scientists are still waiting for the government to release revised estimates of energy production, including imports and exports, over the past decade. Liu says that his team’s estimates are unlikely to change when the latest data are released later this year, but Peters says that the figures may need to rise by as much as 7%.

    Such uncertainty arises in part from the many different ways to define and measure energy consumption; researchers do not know what kind of assumptions the Chinese government is making with its data. “If China reported their CO2 emissions, then we would know the assumptions that they want to make and many of these issues would then go away,” says Peters. The challenge, he adds, is unlikely to be resolved anytime soon.

    “With Chinese energy statistics,” he says, “there is always a ‘but’.”

    See the full article here.

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 2:08 pm on July 29, 2015 Permalink | Reply
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    From astrobio.net: “‘Carbon sink’ detected underneath world’s deserts” 

    Astrobiology Magazine

    Astrobiology Magazine

    Jul 29, 2015
    No Writer Credit

    1
    Scientists followed the journey of water through the Tarim Basin from the rivers at the edge of the valley to the desert aquifers under the basin. They found that as water moved through irrigated fields, the water gathered dissolved carbon and moved it deep underground. Credit: Yan Li

    The world’s deserts may be storing some of the climate-changing carbon dioxide emitted by human activities, a new study suggests. Massive aquifers underneath deserts could hold more carbon than all the plants on land, according to the new research.

    Humans add carbon dioxide to the atmosphere through fossil fuel combustion and deforestation. About 40 percent of this carbon stays in the atmosphere and roughly 30 percent enters the ocean, according to the University Corporation for Atmospheric Research. Scientists thought the remaining carbon was taken up by plants on land, but measurements show plants don’t absorb all of the leftover carbon. Scientists have been searching for a place on land where the additional carbon is being stored—the so-called “missing carbon sink.”

    The new study suggests some of this carbon may be disappearing underneath the world’s deserts – a process exacerbated by irrigation. Scientists examining the flow of water through a Chinese desert found that carbon from the atmosphere is being absorbed by crops, released into the soil and transported underground in groundwater—a process that picked up when farming entered the region 2,000 years ago.

    Underground aquifers store the dissolved carbon deep below the desert where it can’t escape back to the atmosphere, according to the new study.

    The new study estimates that because of agriculture roughly 14 times more carbon than previously thought could be entering these underground desert aquifers every year. These underground pools that taken together cover an area the size of North America may account for at least a portion of the “missing carbon sink” for which scientists have been searching.

    “The carbon is stored in these geological structures covered by thick layers of sand, and it may never return to the atmosphere,” said Yan Li, a desert biogeochemist with the Chinese Academy of Sciences in Urumqi, Xinjiang, and lead author of the study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “It is basically a one-way trip.”

    Knowing the locations of carbon sinks could improve models used to predict future climate change and enhance calculations of the Earth’s carbon budget, or the amount of fossil fuels humans can burn without causing major changes in the Earth’s temperature, according to the study’s authors.

    Although there are most likely many missing carbon sinks around the world, desert aquifers could be important ones, said Michael Allen, a soil ecologist from the Center for Conservation Biology at the University of California-Riverside who was not an author on the new study.

    If farmers and water managers understand the role heavily-irrigated inland deserts play in storing the world’s carbon, they may be able to alter how much carbon enters these underground reserves, he said.

    “This means [managers] can take practical steps that could play a role in addressing carbon budgets,” said Allen.

    2
    Researchers gathered groundwater flowing under the desert sands. The amount of carbon carried by this underground flow increased quickly when the Silk Road, which opened the region to farming, began 2,000 years ago. Credit: Yan Li

    Examining desert water

    To find out where deserts tucked away the extra carbon, Li and his colleagues analyzed water samples from the Tarim Basin, a Venezuela-sized valley in China’s Xinjiang region. Water draining from rivers in the surrounding mountains support farms that edge the desert in the center of the basin.

    The researchers measured the amount of carbon in each water sample and calculated the age of the carbon to figure out how long the water had been in the ground.

    The study shows the amount of carbon dioxide dissolved in the water doubles as it filters through irrigated fields. The scientists suggest carbon dioxide in the air is taken up by the desert crops. Some of this carbon is released into the soil through the plant’s roots. At the same time, microbes also add carbon dioxide to the soil when they break down sugars in the dirt. In a dry desert, this gas would work its way out of the soil into the air. But on arid farms, the carbon dioxide emitted by the roots and microbes is picked up by irrigation water, according to the new study.

    In these dry regions, where water is scarce, farmers over-irrigate their land to protect their crops from salts that are left behind when water used for farming evaporates. Over-irrigating washes these salts, along with carbon dioxide that is dissolved in the water, deeper into the earth, according to the new study.

    Although this process of carbon burial occurs naturally, the scientists estimate that the amount of carbon disappearing under the Tarim Desert each year is almost 12 times higher because of agriculture. They found that the amount of carbon entering the desert aquifer in the Tarim Desert jumped around the time the Silk Road, which opened the region to farming, begin to flourish.

    After the carbon-rich water flows down into the aquifer near the farms and rivers, it moves sideways toward the middle of the desert, a process that takes roughly 10,000 years.

    Any carbon dissolved in the water stays underground as it makes its way through the aquifer to the center of the desert, where it remains for thousands of years, according to the new study.

    Estimating carbon storage

    Based on the various rates that carbon entered the desert throughout history, the study’s authors estimate 20 billion metric tons (22 billion U.S. tons) of carbon is stored underneath the Tarim Basin desert, dissolved in an aquifer that contains roughly 10 times the amount of water held in the North American Great Lakes.

    The study’s authors approximate the world’s desert aquifers contain roughly 1 trillion metric tons (1 trillion U.S. tons) of carbon—about a quarter more than the amount stored in living plants on land.

    Li said more information about water movement patterns and carbon measurements from other desert basins are needed to improve the estimate of carbon stored underneath deserts around the globe.

    Allen said the new study is “an early foray” into this research area. “It is as much a call for further research as a definitive final answer,” he said.

    See the full article here.

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