Staff Journal

The Land Turned Upside-Down

What would Britain’s landscape look like in a zero carbon future? Peter Harper, CAT’s Head of Research and Innovation, explores the possibilities.

If the UK undertook to ‘decarbonise’ itself completely, what effect would this have on our land and landscape? The short answer is: a very big one. Let’s assume that all sectors of the economy had to go to zero. Let’s also assume this is to be done principally by market forces, guided by a fiscal framework set by the government, in accord with a binding international agreement. Most likely this would take the form of some kind of ‘carbon price’ applying to all greenhouse gas (GHG) emissions. Since the world economy is critically bound up with GHG emissions, the setting of a ‘carbon price’ high enough to drive decarbonisation would utterly transform the pattern of transactions in all sectors, generating a new economic framework that I shall call ‘carbonomics’.

Land use (including agriculture and forestry) accounts for between 10 per cent and 35 per cent of world GHGs, depending on how you do the sums. Its emissions are hard to measure accurately, but fortunately we are used to rough and ready conventions and estimates for the purposes of agricultural subsidies. Carbonomics would also generate subsidies, where a land-use process could demonstrate carbon-reductions or carbon sequestration. On the other hand it would impose financial penalties on GHG-emitting processes. It is the vast difference between carbonomic prices and present economic prices that would turn land-use upside-down. In particular it results in huge decreases of livestock.

In what follows I have tried to re-rank land-use priorities according to the new rules. It will be obvious that in many cases we really don’t know the answers. OK, so let’s get cracking on the research. If the research community cannot get to grips with this, one of the greatest challenges ever faced by humanity, what on earth is it for?

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Priority 1:

Conservation of forests and other natural reservoirs

The release of CO2 and other greenhouse gases (GHG) through processes such as clearing forests and disturbing peatlands accounts for up to a quarter of current world GHG emissions. In their intact state forests also have important value for biodiversity and might also be active sinks. Further, they play a large and incompletely-known role in local, and possibly global, climate regulation. It is imperative that these reservoirs are conserved, and incentives found for maintaining their integrity.

This is particularly true for the tropics, but temperate forests also have value as reservoirs. There are of course virtually no primary forests in the UK, but there are important areas of peat that need careful consideration.

Priority 2:

Production of low-emission raw materials for food

There is likely to be strongly increasing pressure on land, with consequent rises in food prices. Tropical systems and soils are often fragile and prone to disruption by extreme weather events. There will be a premium on robust temperate soils, and in the UK it would be as well to look after them. There probably will be risks to food security in the coming decades, and it would be a good idea for the UK to reduce its dependency on imported foods. In fact in some circumstances the UK might become a net exporter.

Animals are not low-emission sources of food, and neither do they use land efficiently, so ‘carbonomics’ will tend to drive them out of the system. Where might they survive? Here are some suggestions (not ranked):

• In situations where the release of CO2 from conversion of pasture to arable or other uses can be shown to outweigh the warming potential of continued grazing over a given time-scale.
• Where stock can be shown to improve overall performance of farms under carbonomic rules.
• Pigs and poultry are not high emitters of methane, although there is still a potential problem of manure management and nitrous oxide. If this latter problem can be solved there is scope for animal production from say press-cake, fermentation wastes, catering wastes and the like, to avoid these animals inefficiently competing with humans for grain and soymeal. A school for instance might have a pig, fed on animal-free food waste, consumed at one almighty annual feast. Backyard poultry might make a comeback.
• Managed grazing of habitats for conservation and other values. The local benefits and non-local disbenefits would have to evaluated in each case.
• In marginal areas, where absolutely nothing else is feasible. This might be thought to apply to upland sheep, but if (according to carbonomic rules) each livestock unit needs to be balanced by an active sink, even these might not be economically viable.
• As conserved populations of ‘rare breeds’, perhaps in ‘City Farms’, allowing more contact between people and farm animals.

A more food-self-reliant Britain would easily produce enough basic foodstuffs. Presently less than 25 per cent of UK agricultural land is devoted to crops, and of this some is forage for animals. The reduction of livestock would free large areas of land for other uses. In the UK, and the west generally, agriculture is dominated by grass and grazing, and these would be the areas most strongly affected by low-carbon drivers. Grasslands are often unsuitable for arable crops, but it does not follow that the ruminants will invariably survive high carbon-prices: there will always be a price at which it is more economic simply to leave the land unused, or (preferably) to manage it in some other (low-carbon) way.

Should low-carbon agriculture be organic? It is widely claimed (and assumed as a given in the movement itself) that organic production has lower GHG production than conventional farming. This is disputed, and it is difficult to disentangle the real evidence from the inevitable biases. Broadly, organic practice avoids the energy penalty, and some of the nitrous-oxide emissions, of the production of Haber-Bosch nitrogen, but has lower yields. Therefore although the inputs are lower, so are the outputs, and in consequence emissions per kg of useful product are often little better than conventional levels, and in some cases worse. This needs further study.

Priority 3:

Renewable production of carbon-sequestering raw materials

This has a high rank for land use because it can potentially displace high-carbon raw materials and lock up photosynthate in a stable solid form. The phrase ‘renewable’ is used to indicate a continuous process. Thus plant materials are grown, absorbing carbon dioxide, harvested and converted into some stable and useful form, then replaced by further crops on the same land. An obvious example is wood used in building and furniture, but many other fibrous materials can be envisaged such as hemp, cereal straw, oilseed rape straw and miscanthus. The new WISE building at CAT, for example, is built largely of timber and a hemp-lime composite, embodying hundreds of tonnes of CO2.

Priority 4:

Sequestration of carbon in soils

Sequestration is destined to be a crucial part of a low-carbon strategy. It is most commonly spoken of in the context of ‘Carbon Capture and Storage’ of CO2 from the combustion of fossil fuels. While this is a step in the right direction, it does no more than cancel out the emissions from the fossil fuels and might be termed ‘passive sequestration’. It does not actively withdraw CO2 from the atmosphere.

Various chemical options have been explored for active CO2 removal and conversion into stable solids, justifying continued and vigorous research. For the time being, however, the only practical technology we have is natural photosynthesis. This knits CO2 into larger carbon-rich molecules in various forms, some of which can be stored permanently, either through practical and industrial processes as discussed above, or in the biosphere itself in the form of standing biomass, litter, or resistant forms of carbon in the soil. A defining feature of organic practice is the addition of organic matter to the soil; if this results in a permanent increase in soil carbon, it should attract a carbonomic credit. In fact ‘farming for sequestration credits’ could become an important part of the agricultural economy. It could have further benefits in biodiversity, erosion-resistance, plant health and so on.

Strong interest has arisen recently in another resistant form of carbon, elemental carbon in the form of charcoal, sometimes known as ‘biochar’. This is produced in various ways from biomass or certain other waste materials, and can apparently be incorporated in large quantities into natural soils without damaging their fertility or other properties. In fact under some circumstances there might be improvements in soil fertility, and this might render the conversion of grazing land into arable a practical possibility.

Biochar is capable of adsorbing large quantities of other substances, and might be able subsequently to release them to plants. This suggests, for example, the use of biochar to absorb potentially polluting nitrogen compounds from sewage and industrial processes, later to provide slow-release nutrients for bioenergy crops while at the same time sequestering carbon.

Priority 5:

Low carbon fuel production

Production of low-carbon materials and energy is likely to focus on high cellulose crops (such as grasses, miscanthus, hemp, trees) used for heat or combined heat and power (CHP). Complementarily, the wet/biogas route deserves re-examination, using dedicated feedstocks such as fresh grasses harvested at different times of the year, as well as non-farm biological wastes. These technologies are twice to three times as efficient as liquid biofuel crops in terms of land take and offer much larger reductions in GHGs, including possible net sequestration. At the same time the ‘second generation’ technology of converting cellulose to sugar and thence alcohols will offer a modest but disproportionately useful source of liquid fuels.

Priority 6:

Protection of biodiversity

This would be possible, with careful design. In the UK wildlife has always had to fit in where it can, so not much change under carbonomic rules! There might well be positive synergies between biodiversity and lowcarbon desiderata if we work at them. If biodiversity is recognised as important it should attract financial support and become another income stream for farmers and local communities. A lot of diligent research work of a generic kind is urgently needed here, because a rapid transition might not leave enough time for investigations in every specific case.

Priority 7:

Shifting aesthetics

Recreation and landscape values would have to change. The countryside would look different. There would be more trees, more crops, and relatively few animals. It would be less ‘open’. Many views would be cluttered. There would be energy processing going on, power lines, wind generators, chippers, biogas digesters, distilleries, more tanks and silos, and so on. The change of aesthetic required is similar to that which obtained in wartime, when it was considered bad form to complain about airfields on farmland or barbed wire on beaches. And anyway, under the carbonomic rules, fuel for your SUV might cost £50 a litre while wind-generated electricity might be the only kind available. We might even see erstwhile NIMBYs begging for more windfarms so they can charge up the electric Mercedes and take little Samantha to her ballet class…