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Drawdown Impossible? | Why trees will compete with crops in the great mission to sink carbon.


25 February 2021 – by Roger Goodman


Three colossal claimants are gearing up for the monumental task of reversing climate

change while properly feeding everyone. There may not be room on earth for all three.


One such participant is the agricultural sector. Most people want not only sufficient healthy food but also meat, while room is needed for fibre crops like cotton, plus wool producing livestock. Another needful party is habitat for biodiversity. The other is tree plantations for carbon drawdown on account of the helpful penchant of trees to eat carbon dioxide.


Since the 1950s ‘intensive’ agricultural methods have led to spectacular gains in food production globally but have come at the expense of biodiverse habitats. As the global population has exploded, food production has broadly managed to keep pace due to the efficiency of intensive, high input farming methods which consume artificial fertilisers and pesticides and utilize genetically improved seedstock, as well as advances in mechanisation. The ready availability of new ground from the clearing of unprotected wild lands has facilitated this growth.


Ecologists have been pleading for increased protection of wildlands even as they become increasingly aware of not only the sheer number of species out there, but also of the interdependence of those myriad organisms, pointing out that whenever one more creature or plant is removed from the picture, the whole is ever so slightly less resilient to further shocks. Trees draw down carbon with great efficiency, but the more biodiverse, stable and intact an ecosystem is, the more perfectly it does it.


Scientists warn that simply reducing greenhouse gas emissions or even eliminating them is not enough to pull us back from a disastrous climate change trajectory. The world also needs, they say, to retrieve the accumulated carbon dioxide we’ve dumped into the sky. They call this process carbon sequestration, with ‘drawdown’ (the actual shrinkage of atmospheric CO2 concentrations) its ultimate aim.


Drawdown can utilise either machines or natural processes. The Direct Air Capture (DAC) process aims to filter carbon dioxide directly out of the atmosphere. A number of demonstration plants exist and two are operating commercially but to make the necessary impact the industry would have to be scaled epically. Further, DAC businesses would need either customers for ludicrous volumes of carbon dioxide, or much more help from governments.


In addition to mitigation (slowing emissions) and drawdown (negating existing concentrations), a third option exists encompassing a gaggle of theorized solar radiation (SR) technologies. The idea is to deploy large reflective surfaces to repel as much of the sun’s heat as possible. For example, fleets of ships have been proposed to spray seawater skywards to form reflective clouds, and some people hope we can place a giant mirror between the earth and the sun. Or inject calcium carbonate or sulphate particles into the atmosphere. Many scientists and climate campaigners oppose all or most such ‘geo-engineering’ ambitions.


Then there are the natural sinks. C02 is eaten alive by trees, of course. They love the stuff. This applies to all vegetation, which sequesters the carbon component and sheds the oxygen. Some of that carbon finds its way into the soil.


Like forests, farmland is a carbon sink. When a farmer ploughs a field, carbon escapes. Hence the more that her soil remains covered by grass or crop, the more carbon remains safely within it. And that carbon benefits her crops, which love the stuff of course. Farmers who intend sequestering carbon use various procedures such as using chemicals to kill grass instead of ploughing, or running pigs or chickens to distribute carbon-rich manure.


Natural sinks tend not to attract capital. Natural sinks are not sexy. They appear to be doing nothing (until you turn your back on them). And they can fail. Forests can burn, for one thing – an increasingly likely scenario. Also, we cannot know that a lovingly established plantation won’t be razed at some future point by profit hungry (or angry) locals even if formalised assurances are given in the present. And trees do suffer epidemics of parasites and disease.


Forests can reduce groundwater levels, they irritate some communities who value certain long established cultural markers such as livestock industries and grassy vistas and, with temperatures rising globally they may lose their status as carbon sink and instead become, awkwardly, carbon source.  And it may well be that the carbon sinking nature of trees may be negated by the fact that grass and crops, which tend to be light in colour, reflect more sunlight back to space than do trees, which tend to be dark.


Nevertheless since tree growing, and in particular the re-establishment of habitat for biodiversity – which on vast scales would mostly take the form of programmed abandonment of farmland – is cheap compared to other options, it would seem an obvious solution for the Drawdown.


But the globe’s population, despite the rate of growth dramatically slowing in recent decades, will creep towards 10.8 billion by 2100. Further, as people’s purchasing power climbs and parents seek healthy and abundant food for their children, farmers will be asked to churn out ever greater tonnage of grain in particular at an ever faster rate.


Intuition might tell us then that more land devoted to farmland will be required. Biodiverse habitat can be protected by decree of course, such that once the time comes that the biggest perpetrators of large scale deforestation have been reigned in, extant habitat could be regarded as confirmed long term carbon sink. But a surface appraisal does suggest that a clash for space must eventuate between agriculture and tree plantations for carbon sequestration.


Certain other land use contenders are lately approaching a critical mass of social unacceptability and are unlikely to proceed at scale. One such is cropping for biofuel. Another is forestry for power generation.


Tree enthusiasts would like 900 million hectares in order to plant enough trees to draw down 25 percent of the CO2 in the sky. Let’s ignore the mind-numbing thoughts you’re having right now such as how do you find landholders who actually want you to do that on their farmland and how do you even get to some of those interesting places with a truck load of trees? The main issue is that in planting trees we’re inhibiting some other kind of rural activity. Certainly agroforestry is a much loved supplement to farming but not everyone can or will take it up. Tree plantations and biodiverse habitat would therefore steal space from livestock in particular, while cropping will continue to dominate arable country.


Some demand for tree space might be filled by compensating rangeland owners but there would surely be a concomitant spill-over of grazing into arable land where wheat, maize, rice and soybeans are currently produced for the world’s plates and bowls. In other words, cows will be employed to chomp grass where corn now soars and goats will be called in to waste their rock climbing talents on the fertile flatlands. Cultures built around livestock and meat are deeply embedded and enduring.



There won’t be enough space on the earth. Will there?


Well here’s a funny thing. There are two competing strands of thought in regard to generating enough calories for the world that’s coming, each worldview denouncing the other as adorably antiquated. One of these two comprises that subset of dirt-love that incorporates everything from subsistence farming to organic farming, silvopasturing, permaculture and biodynamics. Let’s use the term agroecology for simplicity’s sake.


Agroecology has so much going for it. It’s friendlier to biodiversity, doesn’t use chemicals much, leads to quieter and more fulfilling lives (it is said), steadily enriches the soil and reduces greenhouse emissions by 40%. Though with tweaking, agroecology can be amply productive, for now the main contender is at least empirically unassailable: High Input Agriculture.


High input farming may also be called intensive agriculture, industrial ag, commercial ag or (disparagingly) chemical farming or monoculture. Both extensive (spread out) and intensive (concentrated) enterprises can be regarded as high input if they are predicated on the liberal consumption of manufactured consumables, which include artificial fertilizers, chemical pesticides and herbicides and advanced crop and animal strains, as well as (often) irrigation regimes and the turnover of advanced equipment. 


High input farming has been the default paradigm for profit-motivated farmers in the global north since the early twentieth century and for similarly ambitious men and women in the global south for less time. Without a doubt this framework offers at least the promise of profit, expansion, and modernity in the countryside. But it has been criticized for its resultant externalities including soil degradation, contamination of streams and groundwater with fertilizer and pesticides, the loss of insects and birds, the clearing of biodiverse habitat for expansion, and high greenhouse gas emissions.


High input farming has been evolving in some places to be more sustainable. Terms such as conservation ag, regenerative ag and sustainable ag are used by broadscale farmers utilizing impressive machinery that conserves moisture, soil structure and carbon by reducing tillage, among other processes.



We’re going to need more food, aren’t we? And we need lots of space for trees, don’t we? So we’re at an impasse, right?


Not so, say proponents of a newly theorized variation on high input agriculture. They refer to their direction as Sustainable Intensification (SI). Here’s how it is said to work. The output of high input farming (vis a vis traditional ag) is so impressive that under an all-SI scenario land usage could actually fall by almost 40 %, and some of the abandoned land could be repurposed as wildlife habitat.


To help the world’s traditional farmers to convert to SI, whole new logistical systems would kick in so that the most efficient inputs, equipment and practices could be injected into isolated hinterlands. Everyone, say the SI folks, would have access to patented seedstock, targeted chemicals and micro-irrigation, almost everyone would be producing mostly one of the four main plant crops (wheat, rice, maize, soybean), markets would welcome all output, and transportation systems would be finetuned. In other words, the intense nature of high input agriculture would be scaled up globally in an epic project to feed the world without further harming biodiversity, and maybe even saving some space for carbon-sinking trees. Intensification then, would be intensified.


The proponents of SI are passionate and seem confident, but the champions of traditional ag are equally adamant, and eloquent. They opine that making organic fertilizers and locally suitable crop varieties more widely available will adequately support farmers in the global north and south to produce good yields without “chemical-soaked monocultures” and without the intense confinement of animals.


Crucial issues for humanity are at stake then in an apparent impasse over available land. Firstly, biodiverse habitat is a perennial and necessary claimant. Throughout the twentieth century a global norm developed: that biodiverse spaces should be retained. Hence, pressure on retrograde leaders like Brazil’s Jair Bolsonaro and the forestry and oil palm majors, plus incentives to protect forest and peatlands in the Congo basin and elsewhere may be all that is needed to broadly stabilize tropical zone habitat loss.


The tree plantation concept needs a lot more consideration. Since trees are some super-efficient, super cheap and rather pretty DAC machines that also do other great things, it would be tempting to prescribe them as The One drawdown solution. Even taking into account their unfortunate traits such as light absorption and a tendency to burn or lay down, if suitable land and capital was limitless it would seem like a beautiful and touching thing to blanket the world in trees in order to save it.


But land is not limitless and since there is no vacant space out there to which no one or nothing has not already laid claim, tree plantations will be in competition with a growing and necessary demand for biodiverse habitat and cropland even if the SI proponents are correct when they project that their methods will minimise the need for arable land. And that’s without counting sheep, cows, and goats.


It seems that hopes of tree plantations blanketing a hypothetical tract the size of Brazil will have to be curtailed. Meanwhile, DAC research is progressing, and while its imagined scaleup leaves eyes watering, the nascent technology has a chance of success.


Most congenial of all though, would be for the fortunate of the world to avail themselves of that tried and true technology that should be the easiest of all to deploy – to simply use less energy.

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