Climate blog - Reports and essays: May 2016 to November 2022
February 25th, 2021
Drawdown Impossible? | Why trees will compete with crops in the great mission to sink carbon.
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.
March 1st, 2020
The rising ocean is already a killer. Here’s why we must believe this counter-intuitive, slow-motion news story
Last August the geographically and numerically miniscule Pacific state of Tuvalu hosted the Pacific Islands Forum. Australian Prime Minister Scott Morrison on landing was greeted by a dramatization of sea level rise involving semi-submerged school children, flag waving and plenty of smiles. It was clearly intended to be educational rather than confrontational.
But Morrison appears to have gone to Tuvalu with a resolve to shift not an inch on coal or on climate change. A communique materialized which failed to mention coal at all. It was noted that except for Australia all of the countries present agreed to a call for a global ban on new coalmines and coal-fired power stations.
Later the forum’s chairperson and former Prime Minister of Tuvalu, Enele Sopoaga declared himself “stunned by the un-Pacific tenor and manner of the Australian prime minister… much against the concerns and the tears that were shed by the Pacific Island leaders.”
To be fair Australia had, ahead of Morrison’s arrival promised to redirect $500 million in aid funding over five years starting in 2020 to help Pacific nations invest in renewable energy and 'climate and disaster resilience'.
Meanwhile, New Zealand Prime Minister Jacinda Arden recently committed funds to assist Fiji in relocating communities already struggling with inundation from rising seas.
Calls from low lying states for the actual polluting nations to act on emissions have been largely ineffectual, while requests for the funds required for effective adaptation, particularly seawalls have had mixed results, such that increasingly, small Pacific nations are making the case for extraction of people as in a slow motion emergency.
The western half of the Pacific Ocean in general is the most threatened part of the world, with the Solomon Islands considered to be most at risk from rising seas along with parts of Papua New Guinea, the Philippines and even northern Australia, particularly the Torres Strait and the Gulf of Carpentaria.
This local concentration of sea level rise feels inexplicable when we imagine monolithic oceans rising and falling each day with the tides but otherwise evenly spaced out over the vastness. We tend to picture that water finding its natural level as surely as a swimming pool finds its level after a few minutes without occupants.
But there are some easily understood reasons why the ocean is getting deeper faster in some places than in others and is even falling in some areas.
All locations are already affected to some extent by ice loss and thermal expansion of water. While melting sea ice doesn’t add to the sea’s depth, melting land ice does. This includes montane and Arctic glaciers and the Greenland and Antarctic ice caps, all of which are melting at an accelerating rate.
The other primary cause of sea level rise has been the ocean expanding as it heats. Of course, since the tropics face the sun very directly, tropical seas accumulate heat faster than elsewhere so thermal expansion is greater.
The melting of earth’s great ice sheets has some surprising effects. Isostatic rebound is one – as an ice sheet melts, the landmass on which it sat is free to rise to its more natural altitude. This causes the nearby sea to effectively fall while causing distant seas to rise.
Plus, ice sheets have gravitational pull on all the world’s oceans such that when ice sheets fade, the sea slides away to where gravity now wants it to be – toward the tropics. And the melting of the ice caps is contributing to change in the earth’s spin axis, further shifting water toward, once again, the tropics.
Tectonics has a part to play – the 2004 Indian Ocean tsunami led to measurable, permanent changes in sea level over a vast area. Then there’s subsidence, both natural and manmade such as from ground water extraction, and differences in the width and slope of continental shelves.
If geophysical forces represent the plodding, relentless side of sea level rise, atmospheric forces are dramatic, destructive and in our face right now. Witness changes in ocean currents such as the warm, massive invisible river that runs north-south down Australia’s east coast. Most of these currents are speeding up due to faster winds. There are also currents called gyres which are like whirlpools the size of oceans and they pile up water in their centre, up to a metre more than on their outer edge.
The world is getting more rain, so more water exits river deltas, adding to sea level differentials. Winds are getting stronger, notably in the western tropical Pacific, pushing Pacific Ocean bulk broadly westwards.
Wave heights are increasing. In its 5th Assessment report the IPCC states that particularly large waves are becoming more common in the tropical South Pacific. Incrementally stronger winds, changing wind directions and higher waves all add to the sea level rise differential between regions.
The strongest cyclones are most likely getting stronger and in the South Pacific they’re occurring further south. These effects working together can result, at the very least, in increasingly destructive storms in certain regions compared to others with associated amplifying effects on sea level.
But the storminess story gets even more troubling. Several factors appear to be multiplying the destructiveness of storm surges in certain regions. Storm surge refers to the unusually high water level that causes so much destruction during wind storms.
But measurements have shown that mean sea level rise is statistically correlated to a rise in sea level extremes. In other words, sea level rise breeds more sea level rise. Compounding this, the faster the underlying rise is, the shorter the return period for extreme days.
A 2015 study in Nature Climate Change came to some astounding conclusions about the confluence of rising sea level and increasing storminess. A commentary on the study stated that “even the [authors’] reduced-emissions calculations suggest a 4- to 75-fold increase in the [coastal inundation] flood index—that is, the combined heights and durations of expected floods—across the locations. With business as usual, the flood index might go up 35 to 350 times.” This is the extraordinary degree to which the confluence of two factors can amplify effects.
In 2013 the strongest storm to ever make landfall anywhere on earth barrelled into an unfortunately warm, shallow, funnel shaped bay in the eastern Philippines. The city of Tacloban was devastated by a 5-7m surge and more than 6,000 people perished, most at the hand of the monstrous sea.
Yet an 1897 typhoon had struck the same bay with a surge only half as high at Tacloban, despite having been of similar height on the open Pacific coast. Why the height difference? It’s conceivable that in 2013 the magnifying effect of a higher mean sea level in tandem with increased storminess generated a freakily amplified wave set.
Our psyches have not evolved to deal with the concept of a rising ocean. The strange reality of big regional differences in the rate of the unfolding phenomenon is even less intuitive. So a little science can help us understand why Pacific peoples are reaching out with urgency. Let’s not assume they are exaggerating about what they see. They are not.
September 30, 2017
May 14th 2016