Reforestation: A science-based argument

Submitted by AWL on 18 December, 2019 - 10:12 Author: Misha Zubrowski

The article below is a response to one written by Paul Vernadsky, linked. See here for the original article which Paul Vernadsky is responding to.

The insights from Paul Vernadsky’s discussion piece point towards an expansion of what we say on transitioning away from animal-based food production, not a deletion.

The piece also, I think, makes some spurious assertions or arguments.

A general argument and detailed backup from scientific literature demonstrate — contrary to Paul’s unsubstantiated assertion to the contrary — that an aim of “phasing out of almost all animal products” is based on serious climate science.

The relevant passage from my initial piece (Solidarity 522, 23 October) is, although this should be taken in context:

“Many changes to the food industry would reduce its negative environmental impact, while enabling nutritionally good, diverse and enjoyable diets. We support the application of science and technology to food production, and increased output per unit land and per unit human labour is, all else being equal, a good thing. […]

“Crucially, too, we advocate the phasing out of almost all animal products (with the added benefit of reducing the needless extreme suffering of billions of sentient beings). Animal based food production is more energy- and land-intensive and so has a higher environmental impact than directly plant-based food production, which would also free up substantial land for carbon sequestration through tree-planting.

“We advocate seriously funded research and development into substitute foods to facilitate a society-wide transition. Genetic engineering is in itself not problematic, and genetic engineering of low-emissions substitute foods is positive.”

This argument is entirely separate from arguments based on animal welfare and suffering. And it does not at all indicate phasing out animal products from medical testing.

Inefficiency of animal products

To first approximation, in broad brush strokes, the argument depends on how food chains work.

Plants take in carbon dioxide and water, and through photosynthesis convert it into sugar and oxygen. They use energy from sunlight for photosynthesis, and the sugar stores the energy within them — some is stored as fat or protein — with oxygen released.

Animals eat plants and breathe in oxygen, and through aerobic respiration they break down the sugars (and other stored energies) to release energy for their own use; creating carbon dioxide and water. This energy is used for movement and staying alive, heating the body in mammals, and for growth and repair of tissues.

Other animals can eat those animals — or their eggs or milk — and extract energy from their tissues through respiration. The process goes so on; naturally you have a balanced carbon cycle.

Ultimately all of this energy derives from the sun, but the further up the food chain, the less efficiently the energy has been transmitted. Animals, including humans, can only digest and extract energy from a proportion of the food they eat. The rest is lost with their excretion. Additionally, of the energy they take in, only that stored in tissues can be passed on, and most is used on heating, moving, thinking, and other processes.

As a result, the amount of energy that gets passed up each “trophic level” of the food chain is in the order of 10%. Put another way, suppose the food grown on one field is enough to feed ten humans — relying on that field alone — for a year. It is instead fed to animals, to rear them to make food. The meat (or milk or eggs) produced would be roughly enough over one year to feed one human relying on that alone. (See and

In itself, there’s nothing wrong with this inefficiency.

The first problem comes when the scale and methods of food production has serious harmful effects. Forests are cleared and soil is degraded, destroying natural carbon sinks and damaging biodiversity. Chemical fertilisers and pesticides are very energy-intensive to create, and damaging to surrounding ecosystems. There are further environmental repercussions.

Some places will more easily grow grass, for grazing by herbivores, than crops for direct human consumption. However, meat and milk production just in those places would produce a tiny proportion of the current quantities of animal products. Often, today, animals grazed in such places are given additional food as well the grass beneath their feet; land elsewhere being used to grow this.

To tackle environmental crises and create natural carbon sequestration, we should aim to dedicate an extremely large proportion of the world’s land surface to ecological restoration, rewilding, and mass tree-planting.

Exactly how large? We don’t know. We know, however, that as of now carbon emissions continue to increase, and the climate effects of the emissions have so far been at the upper rather than the lower end of previous estimates. We know that the land areas used for grazing are still increasing in large parts of the world, and in world total have decreased only very modestly since 2000. The climate emergency is such that we should aim for all the feasible emission-reduction policies. There isn’t time to try out just a few, then go on to adopt others if the first tranche isn’t enough.

That suggests aiming for over one trillion — that is, one million million — native saplings to be planted, covering over one tenth the world’s land area. Those trees could remove hundreds of billions of tonnes of CO2 from the atmosphere (see for example The trees will need land currently used for grazing herbivores for food production.

Cows, and to a lesser extent other animals, also produce very large quantities of methane through farting (though the quantities can be reduced by better diets). Methane is over seventy times more potent a greenhouse gas than carbon dioxide over a twenty year period.

Fish farms involve many of the same problems as discussed above, while overfishing and industrial fishing techniques have many damaging effects on the environment.

Detailed findings

“Transitioning toward more plant-based diets that are in line with standard dietary guidelines could reduce... food-related greenhouse gas emissions by 29–70% compared with a reference scenario in 2050”, according to one 2015 scientific research paper, The food system, the same study claims, is responsible for over one quarter of all greenhouse gasses.

A 2018 Oxford University meta-study — — into “[r]educing food’s environmental impacts”, the most comprehensive to date, found that “impacts of the lowest-impact animal products typically exceed those of vegetable substitutes, providing new evidence for the importance of dietary change.” They found “that meat, aquaculture, eggs, and dairy use about 83% of the world’s farmland and contribute 56-58% of food’s different emissions, despite providing only 37% of our protein and 18% of our calories.” It advocates “[m]oving from current diets to a diet that excludes animal products”.

As well as agreeing with the first cited study that food contributes over one quarter of GHG emissions, it noted that “food production creates about 32% of global terrestrial acidification and about 78% of eutrophication [excess nutrients].” Additionally: “Today’s agricultural system is also incredibly resource intensive, covering about 43% of the world’s ice- and desert-free land.”

“Causes of Deforestation of the Brazilian Amazon” a 2004 extensive study by the World Bank — — found that 91% of areas of Amazonian rainforest cleared since 1971 had “been converted to cattle ranching.” They additionally state that “available data strongly suggest that, in terms of the growth and spread of deforestation, cattle ranching is definitely the main economic activity associated with deforestation and that agriculture per se appears to have very little impact on deforestation.”

A 2019 Harvard University study — — argues that “The most readily deployable CDR [carbon dioxide removal] option at scale in the UK is the restoration of its native forests. Reforestation could provide the CDR needed to help meet the UK’s current climate change commitments, and beyond that, to staying within the 1.5°C budget. Animal agriculture is the biggest land user in the UK. Due to its relatively low food output to land use ratio, animal agriculture currently occupies 48% of all UK land.”

“Assessing the Environmental Impacts of Consumption and Production”, a 2010 United Nations report,, stated that “Impacts from agriculture are expected to increase substantially due to population growth, increasing consumption of animal products. Unlike fossil fuels, it is difficult to look for alternatives: people have to eat. A substantial reduction of impacts would only be possible with a substantial worldwide diet change, away from animal products."

A 2010 scientific meta-study — — “yielded a consistent ranging of results for use of land and energy, and for climate change… [p]roduction of 1 kg of beef used most land and energy, and had highest global warming potential (GWP), followed by production of 1 kg of pork, chicken, eggs, and milk.”

“The impact of production of 1 kg of meat (pork, chicken, beef) was high compared with production of 1kg of milk and eggs because of the relatively high water content of milk and eggs.

“According to the Food and Agriculture Organization, for example, the world’s livestock sector is responsible for 18% of the global emission of greenhouse gases. This contribution of 18% was explained by emission of carbon dioxide from fossil fuel combustion and deforestation, emission of methane from manure and enteric fermentation by ruminants, and emission of nitrous oxide from application of fertilizer during cultivation (Steinfeld et al., 2006).

“In addition to changes in production practices, eating less or no livestock products, such as meat, is seen often as a possible solution to reduce the environmental impact of the livestock sector (Carlsson-Kanyama, 1998; Pimentel and Pimentel, 2003; Reijnders and Soret, 2003; Baroni et al., 2007). Indeed, a balanced plant-based diet can provide us with all the nutrients required for a healthy life (Appleby et al., 1999).

“Eating meat, however, is not only a reflection of nutritional needs, but it is also determined by taste, odour, and texture, as well as by geographical area, culture, ethics and wealth (Richardson et al., 1993).

“In member countries of the Organization for Economic Cooperation and Development (OECD), more than one-quarter of the energy content of an average diet still consists of animal products (FAOSTAT, 2009). A massive number of people in developing countries... are turning to this kind of diet (FAO, 2002).”

A “lifestyle change” towards meat-eating is underway. It can be stalled and reversed, not by preaching individual dietary choices, but by social measures: buying or expropriating land for reforestation, and thus increasing relative prices for meat and other animal products compared to plant products; research into and subsidies for plant-based foods; public measures to require availability of plant-based foods in nurseries, schools, canteens, shops, etc.

Meat grown in a lab could facilitate a transition. One 2011 study — — into the environmental impact of such “cultured meat” found that “[i]n comparison to conventionally produced European meat, cultured meat involves approximately 7–45% lower energy use (only poultry has lower energy use), 78–96% lower GHG emissions, 99% lower land use, and 82–96% lower water use depending on the product compared.

“Despite high uncertainty, it is concluded that the overall environmental impacts of cultured meat production are substantially lower than those of conventionally produced meat.”

A 2017 environmental research paper — — found that different sources of beef and fish are worse or better for the environment, but also that “for all environmental indicators and nutritional units examined, plant-based foods have the lowest environmental impacts; eggs, dairy, pork, poultry, non-trawling fisheries, and non-recirculating aquaculture have intermediate impacts; and ruminant meat [cattle, sheep, goats] has impacts about 100 times those of plant-based foods” (see graph below).

Graph: Environmental impacts of broad groups of foods per kilocalorie (available to the human consumer).

Environmental impacts of broad groups of foods per kilocalorie (available to the human consumer). Fig. 8, The environmental indicators are greenhouse gas emissions, land use, energy use, acidification potential and eutrophication potential. Bars show means and standard errors. Plant-based foods are in green; dairy and eggs are in grey; meats are in red; and seafood is in blue. Data from foods grown in greenhouses are not included when plotting this figure. Trawl Fishery = bottom-trawling fisheries; NT Fishery = all other fisheries (e.g. line, purse net, seine net, etc); Recirc Aqua = recirculating important too. Green-aquaculture; NR Aqua = non-recirculating aquaculture (e.g. pond, net pen, flow-through, etc).

Paul's citations support my case

Paul writes: “There is a large literature on food and climate change. Over the last year, a number of significant (and overlapping) reports have been published… [some listed]... None of these reports advocate the phasing out of almost all animal products.”

The IPCC report writes (with secondary citations) that “a vegan diet without animal-sourced foods... defines the upper bound of the technical mitigation potential of demand side measures.” (

Springmann et al 2018 — – found:

“Following environmental objectives by replacing animal-source foods with plant-based ones was particularly effective in high-income countries for improving nutrient levels, lowering premature mortality (reduction of up to 12% [95% CI 10-13] with complete replacement), and reducing some environmental impacts, in particular greenhouse gas emissions (reductions of up to 84%). However, it also increased freshwater use (increases of up to 16%) and had little effectiveness in countries with low or moderate consumption of animal-source foods”.

“A public health strategy focused on improving energy balance and dietary changes towards predominantly plant-based diets that are in line with evidence on healthy eating is a suitable approach for sustainable diets.”

Godfray – – wrote:

“Although meat is a concentrated source of nutrients for low-income families, it also enhances the risks of chronic ill health, such as from colorectal cancer and cardiovascular disease.

“Meat produces more emissions per unit of energy compared with that of plant-based foods because energy is lost at each trophic level... Meat production is the single most important source of methane”.

And Poore – – is clear: “Most strikingly, impacts of the lowest-impact animal products typically exceed those of vegetable substitutes, providing new evidence for the importance of dietary change.”

Official reports, by their nature, tend to make their assumptions as conservative as possible. They do not explicitly, and in as many words, advocate the phasing out of almost all animal products. But they do indicate that would be the most environmentally positive course of action.


Different reports call for different levels of reduction of animal products: but they all call for serious reduction.

Some animal products are much worse, environmentally, than others. There is likewise variation between plant-based products. Perhaps these sections of my previous article should be expanded to make explicit this extra detail, but there is no case for rejecting the sections.

The variations highlight the areas which should be focused on first, and which offer the greatest and easiest emissions reductions. Other changes than shifts from animal products to plant-based products are important too. Greenhouses can be heated from combined heat-and-power stations, or using renewable energy; methods of growing rice, and flooding or otherwise can be changed ( to reduce methane and nitrous oxide emissions; the diets of ruminant animals can be improved very rapidly to reduce farting.

None of those things changes the overall lack of reliable evidence that the climate emergency can be fixed without a drastic increase in reforestation and decrease in use of animal products.

As with many environmental aims with numbers attached — such as 1.5°C warming, or a 2050 global net zero target — the quantity of meat reduction to be advocated cannot be exactly estimated in advance, and to a large extent reflects belief in the political possibilities.

Advocating that the food industry reduce its share of animal products by only 50% or 75%, rather than say 95%, has no precise scientific mandate. We don’t know whether it might be enough to keep climate change manageable. We do know that the climate emergency is deep enough to mandate pressure on all fronts.

This is not about individual or consumer choices — the natural go-to of many liberal environmentalists.

Nor is it about “tak[ing]the focus away from tackling fossil fuel capital”. That charge is sound against liberal vegans, or liberal air-plane boycotters. But my original text, overall, focuses squarely on the fossil-fuel industry. The text does not even mention the animal-products issue, directly or indirectly, in the discussion of the components of the immediate programme to agitate around.

With food as with flying, I focus not on individual behaviour but collective solutions. Of the two, flight reduction would have a bigger negative impact on the lives, well-being, and positive social development of the working class. We seek to achieve it not by preaching individual choices, but by blocking the building of new airports, reversing the tax advantages of air travel (no tax on aviation fuel), developing better rail links, etc.

“Vegan capital”?

My argument is no more soft on or bolstering “vegan capital” than our arguments about public transport are “soft” on bus or rail capital, or our arguments about electricity generation “soft” on wind-turbine or solar-power capital.

We want to rapidly socialise, reconstitute and transform all major corporations; and make a wide variety of good quality foods available at low cost, or free. This not only would tackle food poverty, but enhance human flourishing and freedom.

A transition away from animal products does not imply a lower quality of life. In developed countries today, plant-based diets are generally healthier and more diverse than those involving more animal-based foods. Additionally, one study – – “investigat[ing] in-the-moment eating happiness” found that “of 14 different main food categories, vegetables consumption contributed the largest share to eating happiness measured across eight days.”

Investment in GM research and development could make available lab-grown substitutes to animal products which could be indistinguishable but environmentally better.

Changes on the scale of the food industry as a whole need not even have large impacts on individuals’ eating habits. It would mean, at some point in the future, that if an individual desires to carry on eating many “beef burgers”, they should, probably, content themselves with lab-grown “beef”, or plant-based alternatives.


As with energy, workers made redundant in a transitioning food industry should receive jobs guarantees and retraining. For many, rewilding and reforesting would be an obvious offer.

Our tradition does not look primarily to a state as the agent of change, as the exclusive force in tackling climate change, or to enforcing market forces through taxation. We look to the working-class, organising industrially. We seek to rapidly socialise and transform the commanding heights of the economy.

Not, that is, to expropriate or outlaw the petty bourgeoisie; small-shop owners or farmers; individuals who look after chickens and eat or even sell their eggs; combustion engine hobbyists; or Inuit communities who rely on hunting.

There is nothing totalitarian about a transformation of the food industry, if pursued in a socialist way. And of course some aspects of a socialist environmentalist programme would take longer than others to win the case for. The change I propose would not outlaw animal products. It wouldn’t introduce a “vegan gestapo”. It would instead transform the “commanding heights” of the food industry.

Add new comment

This website uses cookies, you can find out more and set your preferences here.
By continuing to use this website, you agree to our Privacy Policy and Terms & Conditions.