World’s soils have lost 133 billion tonnes of carbon since the dawn of agriculture, study estimates

From The Independent

Amount of carbon released from the Earth is about the same as released by deforestation


Concern has been growing over a ‘soil fertility crisis’, a problem that can be masked by the use of artificial fertilisers Tina Reynolds/Flickr

The degradation of the Earth’s soil by humans has been an environmental catastrophe on a similar scale to the deforestation of much of the planet, a new study suggests.

Experts estimated that 133 billion tonnes of carbon has been removed from the top two metres of soil since farming began some 12,000 years ago, about the same as the total amount lost from vegetation.

However the figure is still dwarfed by the 450 billion tonnes of carbon emitted since the Industrial Revolution began and humans started burning fossil fuels on an unprecedented scale.

Soil is obviously vitally important for the growth of crops that feed humans and livestock. Concern has been growing what some refer to as the “soil fertility crisis”, a problem that can be masked by the use of artificial fertilisers.

Carbon released from the soil also contributes to global warming.

But the researchers suggested the figures showed the potential for soil to absorb carbon, something that could be used to reduce the level of the greenhouse gas in the atmosphere by using different agricultural techniques.

Writing in the journal Proceedings of the National Academy of Sciences, they said: “The incredible rise of human civilizations and the continuing sustainability of current and future human societies are inextricably linked to soils and the wide array of services soils provide.

“Human population and economic growth has led to an exponential rise in use of soil resources.

“The consequences of human domination of soil resources are far ranging: accelerated erosion, desertification, salinization, acidification, compaction, biodiversity loss, nutrient depletion, and loss of soil organic matter.

“Of these soil threats, loss of soil organic matter has received the most attention, due to the critical role [it] plays in the contemporary carbon cycle and as a key component of sustaining food production.”

The total figure for the lost carbon was estimated at 133 billion tonnes, saying: “These soil-organic-carbon losses are on par with estimates of carbon lost from living vegetation primarily due to deforestation.”

The researchers found the UK, northern and central Europe, parts of China and the US corn belt were particular hotspots.

This is partly because of the high levels of carbon that would have originally been in the soil in these areas, but also the type of farming typically practised there.

Unsurprisingly, losses from cropland were significantly higher than from land used for grazing animals. But arid grasslands were also vulnerable if they were over-grazed, leading to significant erosion.

One of the researchers, Dr Jonathan Sanderman, of the Woods Hole Research Centre in Massachusetts, told the website Carbon Brief: “Considering humans have emitted about 450 billion tonnes of carbon since the industrial revolution, soil carbon losses to the atmosphere may represent 10 to 20 per cent of this number.

Read the rest of the story here.



77 thoughts on “World’s soils have lost 133 billion tonnes of carbon since the dawn of agriculture, study estimates

  1. Makes you want to scream….don’t it?

    Here a catastrophe…there a catastrophe….everywhere a catastrophe

      • Oooh, I missed it;

        Experts estimated that 133 billion tonnes of carbon has been removed from the top two metres of soil since farming began some 12,000 years ago

        That is only 11 million tonnes a year – less than people breath out every year (today). It did sound scary though. Catastrophe averted, NEXT…..

      • 133 billion tonnes is carbon. Your computation is carbon dioxide. Their 11 Million tonnes a year is miniscule compared to 121 Billion tonnes a year absorbed by soil in the natural carbon cycle. Nature won’t even notice agriculture’s impact on the carbon cycle

      • There can’t be many places where the topsoil is 2 metres deep. In the UK, I think the average is about 60 cm.

      • Oh.
        And . .
        133billion tonnes of carbon [no mention of manure, I guess].
        Over 60 plus million square miles – so about 2,200 tonnes per square mile.
        2560000 square metres in a square mile [roughly].
        So a bit less than one kilo of carbon lost, per square metre, over a period [and I note that human agriculture doesn’t use every square metre of the land masses, even today. Certainly Heathrow produces no crop.] of
        “since the dawn of agriculture”

        The Earth is pretty big.
        Her oceans, and her land masses are pretty big.
        I once flew over the ‘ears of the rabbit’ crossing Queensland, Australia.
        That took two hours by 747.


    • “The degradation of the Earth’s soil by humans”

      That first line tells us all we need to know about the mind set of the author and likely those who did the study. There is a prevalent belief that humans are a pest on planet Earth and that anyhing we do to improve our lot in life must be harmful to nature in some way. And yet a close look at reality
      would show them that crop productivity has done nothing but increase over time, the planet is greening, forrests are regrowing faster, much of what was endangered in ocean life is increasing and if CO2 continues to rise in the atmosphere we can anticipate a much greener and diverse biosphere in the future.

      • Spot on, Andy patullo. The proof of the pudding is in the eating (in this case even literally!) Our good, competent farmers’ soil improves every year – every year is a record harvest – so why worry?

  2. Seems like the numbers are based upon estimates, not actual measurements. Where has all the carbon gone (cue Pete Seeger). It hasn’t left the planet. Perhaps it was processed through several energy cycles and converted to man-made fertilizers which cannot possibly replenish the soil. [sarc]

  3. This is silly. 133 GT of carbon from 149 Million square kilometers of land surface (I assume that is what they speak about), is about one kilo (2.2 pounds) per two cubic meters of soil. Check me please. Of course, this is microscopic and of course it was not removed, it was moved or altered.

  4. oh…. over 12000 years. So 1 kilo/12000 is … oh bother .08 grams per year per 2 cubic meters. right? Call me in say 50000 years please.

  5. The soil loses carbon the same way an obese person loses weight. They lose same 5 pounds over and over again. The carbon just keeps coming back like the unwanted cat.

    • Good point. The organic soil content is important for three reasons. 1. Retains moisture. 2. Helps earthworms maintain aeration, which in turn helps moisture retention by providing percolation channels . 3. ‘Feeds’ the bacterial microbiome, a very important aid (symbiosis, other) for roots to uptake micronutrient minerals. For intensive cultivation, the three most important elements are nitrogen (only fixed by legume symbionts), phosphorus, and potassium. Those do get depleted, hence NPK fertilizer, with ratios depending on soil and crop. Nitrogen can be replenished by legume rotation, P and K only a little by manuring. Fertilizer has nothing directly to do with soil organic (carbon) content.

    • It is important to realize that with or without farming (man’s intervention) carbon moves into and out of the soil constantly. Example, an untouched forest stores a lot of carbon in the wood. As the trees die naturally and are replaced by others the wood debris falls to the forest floor, rots, and is absorbed into the soil. When there the soil bacteria complete the cycle of oxidizing the carbon to CO2 where it escapes into the air to feed more plants.
      If carbon is in the soil it will eventually return to the air where it came from courtesy the soil bacteria. No human intervention required. Now, is there a difference in RATE if a farmer or logger is involved – perhaps – but that question was neither studied or reported.

  6. Yawn…
    Anymore when I see “Carbon…,” I reach for my pistol. Paraphrasing Bismarck, or one of them fellers.

    Belongs in my “Peak Science” file.

  7. “We developed a model’. They should have asked the farmers who work their soil for a living instead. I lived in Europe for several years and visited a relatives hog farm, one of the 25 largest in Germany at the time. Feed mostly grown on the farm. Soy, corn, oats, canola,… Farmed since about 1400 when main stone buildings were built as a monastery farm. 100 year lease from Catholic church. Soil was in great shape. Manure and stubble plowed in, regular fallowing plan. My Wisconsin dairy farm has been worked since ~1880. Only soil problem is minor hilly erosion, mostly solved by contouring. We use minimum till except on Crop rotation, and all the dairy bedding and manure goes back on the fields to build annual soil organic content. The only places where organic soil content loss is a real problem is the tropics (think Amazon forest fringes) where slash and burn is practiced, or for example Indonesia where tropical rain forest over peat bog is burned to plant oil palm for biodiesel to solve CAGW. Lunacy.

    • Ristvan, so you are saying the only carbon/nutrients to leave the farm is produce/livestock to feed people, no wonder the greens don’t like farmers.

      In all seriousness, I have hiked/canoed a many lake/forests. If you stop to listen, in many mature forest there is no sound, no movement. Go to a farm, there are birds, insects, rodents, mammals (deer, gofers, etc.) all moving around. I question, done selectively and correctly farms are good for diversity. Keep it up! My two cents.

      • Just to make my point, my latest hike this weekend, edging a farmers field for a few minutes the Cicada’s and other bugs were all jumping in front of me. Entering the forest, absolutely nothing but a few mosquitoes. I did see an owl, very rare, he was sitting in a tree, flew away with my noise but on the edge of an old farmers field (in disuse for decades).

      • Duncan, my farm has three large (>40 acre) woodlots. All have been selectively logged, most recently 30 years ago. So pretty dense and mature. One of my many ‘magic moments was stalking a doe whitetail way down in a woodlot ravine (I was disinclined to shoot given the extraction pain and that had already taken a big buck that year), looked up at an overarching oak and there was a resting great horned owl. Now you know that owl wanted me to take the doe so it could feed on the offal for days. Result, happy deer, disappointed owl, thrilled me. Nature is wonderful. We interact with it. But when you love nature, the interaction is responsible and sustainable.

      • I am mostly a city dweller myself but dabble all the time with nature/farms, much more so in my youth. If I was to make an observation, it is those “deplorable’s” that interact with nature the most that actually have the most respect for it. It is this oxymoron that the ivory tower preachers have failed to grasp, in the context of CO2, their naivety, we might be better for it (maybe not). At least a well kept secret….

      • Ristvan owls rarely if ever eat offal. Bubo owls will catch and eat almost anything that moves mammals, birds, snakes, frogs, fish, crayfish, crabs, scorpions(!), even each other, but not offal. But you disappointed a lot of other creature, even those cute little tits are extremely fond of offal.

        About the relative scarcity of wildlife in large blocks of old mature forest. Remember that this is a very unnatural habitat. Under normal conditions wildfire and large animals (mammoths, mastodons, gompotheres, hippopotami, rhinoceros) would ensure a mosaic habitat. And even so there is actually more wildlife than you would think, but most of it is nocturnal or way up in the treetops.

  8. Plants need more CO2. Why would we worry about more CO2 in the atmosphere, right where it is needed.
    They should stop playing with their models and get back to realwork.

  9. Crop yields per acre are progressively increasing and have been for decades, yet we are depleting the soil via farming. Kinda counter to the concept of diminishing returns.

  10. The typos and grammar problems are abundant in this one. There’s also this…

    “…what some refer to as the “soil fertility crisis”, a problem that can be masked by the use of artificial fertilisers.”

    Change “masked” to “solved” and it becomes an accurate statement.

  11. This one is rich too…

    “The degradation of the Earth’s soil by humans has been an environmental catastrophe on a similar scale to the deforestation of much of the planet, a new study suggests.”

    I guess they are talking about that “environmental catastrophe” that resulted in improving agricultural yields by an order of magnitude.

  12. Carbon..
    And then there is Carcon Dioxide..
    Happily mixed in one story.
    Organic matter in soils, likely complex molecules containing carbon, just like wooden furniture or wooden houses. Carbon Dioxide in the atmosphere is something completely different. When is this Carbon thing going to stop? People are built from complex carbon molecules; that is probably where all that missing soil carbon went to..

    • This is interesting too. The thread began with an estimate of the annual Carbon exhaled by humans. Even when corrected for the masses of CO2 vs Carbon, the result is ~3/4 of a Gt. This is 8% of the reputed 9 Gt we produce annually. Small, but not insignificant.

      Humans are about 20% Carbon. Average wt 60 Kg *.2=12 kilos per capita *6.6G people gives a startling 79Gt of walking, talking Carbon.

  13. When I was a boy back on the dairy farm I must have shovelled at least ten million tons of cow dung. I assume I’m not the only one who put ‘carbon’ back into the soil!
    Isn’t it amazing the way these clowns can turn on a dime…one minute farm ‘waste’ is a nightmarish environment killer…the next we’re depleting it! (Where do greenies think the animal manure goes anyway?)

  14. So here we have people interested in the quality of the world’s soils. It may come as a surprise to them that the people most interested in soil quality are those who make their living by long term agriculture. It might also surprise them that rainforest soils are pretty thin in organic content.

    It’s a bad thing for soil to lose its organic quality. But instead of looking at the important issue of soil quality they wander off into the weeds by following only one element (both puns intended).

  15. Link brings up author refering to 10,000 B.C. “… a world without hunan footprint.” If we peg northern glaciers as retreating at 10,000 B.C. another perspective comes into view.

    It was not until around 6,000 B.C. those previosly glacial covered lands built up enough carbon to reach the level of 1,000 grams carbon/square meter. And it took until around 3,000 B.C. for the carbon content to reach a very good level.

    See Fig.4 of Daves, et al. (2016) “Longterm weathering and recent N deposition control contemporary plant-soil C, N, and P”; free full text available on-line.

    Since phosphorus is integral to plants I’ll highlight authors’ observation that post-glacial weathering of rocks took until 4,000 B.C. to get lots of phosphorus available. Fig. 6 shows
    a phosphorus peak around 3,000 B.C. that was already going down by 1,000 B.C.

  16. In this study, a machine learning-based model was fitted using a global compilation of SOC data and the History Database of the Global Environment (HYDE) land use data in combination with climatic, landform and lithology covariates.

    Oh boy, here we go. A global-warming alarmist with “machine learning-based model”. Time to fasten your scientific seat belts.

  17. I live in Manassas, Virginia, the virtual centroid of the Civil War. Every once in a while, I run across internet pages that show pictures of “then and now.” A few times, recently, I came across pictures of Civil War battlefields then and now. What struck me immediately is the fact that “then” (in the 1860s), the landscape was almost completely devoid of vegetation. Today, it is covered with thick forest. I live on a 5 acre plot which is mostly woods, much of it ancient beech trees. But much of it is also new. I find it difficult to believe that the last century saw anything except a strong resurgence of plant life in America.

  18. So…degradation of soils leads to increased Earth greening and higher productivity, since that is indeed the real observation. Okee dokee!

  19. Finally, an article on the real problem. It is hardly a catastrophe that we have to solve within 5 years or we’re all going to die. But when we work on it, we improve soil fertility and increase the nutrient content of foods.

    However, there is so much lying in anything touching on “climate” or “carbon” that I question the ratios given. They could be truthful, but they are just as likely to be distorted in favor of the attack on fossil fuels.

  20. 133 billion tonnes, huh? How do they know it wasn’t 132 billion tonnes or 134 billion tonnes?

  21. Around 10 billion people owe their lives to agriculture. That works out to 13 tons of Carbon (or is it CO2) per person. You need much more to cook over your lifetime.

  22. 1. Carbon in the soil is in no way necessary for farming, it is just a convenience since it (usually) makes soil more easy to work. Many of the World’s best agricultural soils are virtually carbon-free.
    2. Farming by definition means removing nutrients from the soil. These must therefore be replaced, at least in the long term, by weathering, manuring, artificial fertilizers and/or growing nitrogen-fixing crops.
    3. The areas mentioned in the press release “UK, northern and central Europe, parts of China…” are arguably the very areas where farming has been practised for the longest time (4000-6000 years) without any serious decline in fertility.

  23. An inconvenient fact is that organic farming/vegetarianism can end up depleting the carbon content of soil. An acre of topsoil weighs about 1000 tons, and has an organic matter of between 3 and 5 percent.
    Organic farming prohibits the use of herbicides, so requires more cultivation to kill weeds as well as preparing seedbeds. Every time soil is moved the aeration results in bacteria breaking down organic matter thus releasing carbon dioxide to the atmosphere. The organic soils of the fenlands in East Anglia have shrunk due to oxidation following cultivation by 10 feet and more in the past 150 years.
    Vegetarianism/veganism has no use for animals in the farming system, so there is no manure produced to replace organic matter in the soil. Fertility building crops, as they call them, reduce the efficiency of utilisation of land for crop production.
    There also remain the vast areas of grassland in dry and hilly areas unsuited to crop cultivation that would also go to waste.
    Everything is a lot more complicated and interrelated than some would have us believe. The one fact that is indisputable is that we will have 10bn people on the planet to feed.

    • Unfortunately “fertility building crops” only replace nitrogen, not phosphorus, potassium or calcium. These are usually replenished by manure or offal. Try that without any animals….
      On second thought it might not be a problem. If all farming goes organic there will be lots of dead bodies available rather quickly.

    • StephenP,

      As I was an organic gardner for over 25 years in my own (small) garden, what you write doesn’t make sense. Organic gardners use any kind of organics, like peat and cut grasses from lawns to spread between crops, so that little to no tilt is needed and that gives a much better water management, both for too much and to low water. Organic farmed soils should have increased organic content, far more than soils only fertilized by minerals and synthetic nitrogen.

      Further, raw phosphate and Ca/Mg carbonates (often from seaweed) are used, as that is used by the plants only if needed and not much is wasted by leaching into groundwater from soluble monophosphates. Seaweed carbonates also contain a lot of trace elements. Raw phosphate also uranium, but for organic farming, low-uranium ore is used. For monophosphates, uranium and other heavy metals are removed in the process.

      Real vegan would give problems over long periods as that doesn’t return enough nitrogen, although crop rotation with nitrogen fixators as fertilizers may help somewhat. Vegetarians do use milk and cheese, these animals do give a lot of nitrogen, but that never may be applied directly on any organic soil: only after mixing in with other organics and complete composting…

      I don’t think that organic alone can feed the world, as the average yield of organic is about 20% lower than of “classic” agriculture and more expensive as it is more labor intensive.

  24. As a matter of fact in Northern Europe accumulation of carbon in the soil is a serious problem for forestry. Before planting trees it is often necessary to dig or plow through the accumulated layers of forest litter to expose the (carbon-free) mineral soil the tree-plants need to take root.
    And there is literally millions of square kilometers of peat bogs in North America and Eurasia. Almost all of that peat (=carbon) has accumulated since the end of the last glaciation. 133 billion tons of carbon is small change in comparison. In Sweden alone the growth of peat is estimated at 20 million cubic meters per year, multiply that by Russia and Canada….

  25. From the linked article.

    “What we did was develop a model that could explain the current distribution of soil carbon across the globe as a function of climate, topography, geology and land use,” Dr Sanderman said.”

    Why didn’t they say they just made it up? I am sure the funding would still be there.

  26. There is a secret inter-dimensional tunnel and the carbon is sneaking over to Venus. Yeah, that’s it. Must be.

  27. Who is this guy Dr Jonathan Sanderman? He works for Woods Hole Research Centre in Massachusetts. Woods Hole Research Centre? Sounds to me they needed the government funding or go broke.

    • Woods Hole Research Centre has relation to the reputed Woods Hole Oceanographic Institution and has nothing to do with “Research”, much less science.
      It’s an activist group specializing in fear mongering. Hence their latest Nintendo-science garbage.
      Even their name is a fraud.

  28. I think, generally, this concept is correct. Some soils in some places around the world have lost Carbon since agriculture began.

    But, on average, soils are now absorbing a net 2 billion tons of Carbon per year. That is what the Carbon Cylce numbers say.

    Some was lost in the areas which were the early adopters of agriculture – the Fertile Crescent Iran, Iraq, Turkey, Lebanon, extending to Greece and Italy. Some more was lost in the US and Russia in the early 1900s and dustbowl years.

    But that is over now. The soils are now adding back Carbon, partly as a result of the extra CO2 in the atmosphere and partly due to farming practices improving.

  29. “World’s soils have lost 133 billion tonnes of carbon since the dawn of agriculture” Good!

    [Why? You could put some content into your posts and try and add to what we know . . . mod]

    • Hopefully into the atmosphere. Hate to think of it bumbling around South Beach in miss matched bermuda shorts and hawaiian shirt, wearing black socks and sandals. Thats just disturbing.

  30. Funny how no one sees the irony in this. The Romans ran a huge deforestation program, and so did the Chinese. Keep in mind, that agriculture was inefficient by modern standards, so they had to use extensive areas.
    Over a couple of centuries, they easily released like 200-300Gt of CO2, equivalent to about 30ppm. Yet we do not see any antique CO2 peak.
    Next to this, with the end of the ice age, the forestation of the northern hemisphere only started, going along with elevating(!!!) CO2 levels.
    All that will not make a lot of sense, unless you accept the fact, that CO2 is very short lived. CO2 sinks take away about 2% of elevated CO2 levels every single year. Actually CO2 sinks scale perfectly with modern CO2 elevations, as my chart shows.

    With a half life period of only 35 years (which is consistent with the 2% figure), earlier civilizations simple could not enrich the atmosphere with CO2. And our modern civilization will not be able to read levels higher than ~520ppm with current output.
    That reality of course, stands in strong contradiction to the claim, “our” CO2 emissions would stick around for centuries. Nothing could be further from the truth.

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