Stefan Wirsenius

Agricultural intensification in Brazil and its effects on land-use patterns: an analysis of the 1975–2006 period

Does agricultural intensification reduce the area used for agricultural production in Brazil? Census and other data for time periods 1975-1996 and 1996-2006 were processed and analyzed using Geographic Information System and statistical tools to investigate whether and if so, how, changes in yield and stocking rate coincide with changes in cropland and pasture area. Complementary medium-resolution data on total farmland area changes were used in a spatially explicit assessment of the land-use transitions that occurred in Brazil during 1960-2006. The analyses show that in agriculturally consolidated areas (mainly southern and southeastern Brazil), land-use intensification (both on cropland and pastures) coincided with either contraction of both cropland and pasture areas, or cropland expansion at the expense of pastures, both cases resulting in farmland stability or contraction. In contrast, in agricultural frontier areas (i.e., the deforestation zones in central and northern Brazil), land-use intensification coincided with expansion of agricultural lands. These observations provide support for the thesis that (i) technological improvements create incentives for expansion in agricultural frontier areas; and (ii) farmers are likely to reduce their managed acreage only if land becomes a scarce resource. The spatially explicit examination of land-use transitions since 1960 reveals an expansion and gradual movement of the agricultural frontier toward the interior (center-western Cerrado) of Brazil. It also indicates a possible initiation of a reversed trend in line with the forest transition theory, i.e., agricultural contraction and recurring forests in marginally suitable areas in southeastern Brazil, mainly within the Atlantic Forest biome. The significant reduction in deforestation that has taken place in recent years, despite rising food commodity prices, indicates that policies put in place to curb conversion of native vegetation to agriculture land might be effective. This can improve the prospects for protecting native vegetation by investing in agricultural intensification.

The Biomass Metabolism of the Food System: A Model‐Based Survey of the Global and Regional Turnover of Food Biomass

The food and agriculture system is among the largest anthropogenic activities in terms of appropriation of land and biological primary production, as well as alteration of the grand biogeochemical cycles of carbon, water, and nitrogen. Despite its importance in these respects, physically coherent descriptions and analyses of the food and agriculture system regarding the total turnover of fundamental flows (such as biomass) and resource use and efficiency of critical processes (such as animal food production) are relatively scarce. This article presents a survey of the current flows of biomass in the food and agriculture system. The survey gives a mass‐ and energy‐balanced description of biomass from its production on cropland and grassland through its transformations into animal and vegetable food products to its final conversion into respiratory heat, feces, and other residues. This assessment was carried out by means of a physical model that, for eight world regions, calculates the necessary production of crops and other phytomass (plant biomass) from a prescribed end use of food, efficiency in food production and processing, and use of system‐internal by‐products and residues as feed, feedstock, and food. The global appropriation of terrestrial phytomass production by the food system was estimated to be some 13 Pg (1.43 × 1010 short tons) dry matter, or 230 EJ (2.18 × 1017 Btu) gross energy (higher heating value), per year in 1992‐1994. Of this phytomass, about 8% ended up in food commodities eaten. Animal food systems accounted for roughly two‐thirds of the total appropriation of phytomass, whereas their contribution to the human diet was about 13% (both on a gross energy basis). The ruminant meat systems were found to have a far greater influence than any other subsystem on the food systems biomass metabolism, primarily because of the lower feed‐conversion efficiency (calculated as carcass produced by total feed intake, including pasture and other human‐inedible feedstuffs) of those systems.

Efficiencies and biomass appropriation of food commodities on global and regional levels

Abstract In examining the global food supply and demand, the balance of research has favored analysis of the prospects for increased crop production, at the expense of examination of the potential for reducing the production requirements by increases in efficiency and productivity, or by shifts in diets. This has implied that there is a lack of coherent evaluations of efficiency and diet as options for keeping down the long-term production requirements for crops and other food phytomass. This paper presents estimates of current efficiency and phytomass appropriation of major food commodities, performed by modeling all principal flows of biomass in the food system. Estimated overall efficiencies varied from 0.35% for beef cattle meat, to 31% for starchy root tubers (global averages, gross energy basis). The results indicate that there is a most substantial potential for efficiency improvements within the animal food sector, particularly for ruminant systems in non-industrialized regions. It is also concluded that a considerable reduction of the phytomass production might be achieved by shifts in diet, even if assuming no changes with respect to the total share of meat in the diet.

Trends in greenhouse gas emissions from consumption and production of animal food products - implications for long-term climate targets

To analyse trends in greenhouse gas (GHG) emissions from production and consumption of animal products in Sweden, life cycle emissions were calculated for the average production of pork, chicken meat, beef, dairy and eggs in 1990 and 2005. The calculated average emissions were used together with food consumption statistics and literature data on imported products to estimate trends in per capita emissions from animal food consumption. Total life cycle emissions from the Swedish livestock production were around 8.5 Mt carbon dioxide equivalents (CO2e) in 1990 and emissions decreased to 7.3 Mt CO2e in 2005 (14% reduction). Around two-thirds of the emission cut was explained by more efficient production (less GHG emission per product unit) and one-third was due to a reduced animal production. The average GHG emissions per product unit until the farm-gate were reduced by 20% for dairy, 15% for pork and 23% for chicken meat, unchanged for eggs and increased by 10% for beef. A larger share of the average beef was produced from suckler cows in cow-calf systems in 2005 due to the decreasing dairy cow herd, which explains the increased emissions for the average beef in 2005. The overall emission cuts from the livestock sector were a result of several measures taken in farm production, for example increased milk yield per cow, lowered use of synthetic nitrogen fertilisers in grasslands, reduced losses of ammonia from manure and a switch to biofuels for heating in chicken houses. In contrast to production, total GHG emissions from the Swedish consumption of animal products increased by around 22% between 1990 and 2005. This was explained by strong growth in meat consumption based mainly on imports, where growth in beef consumption especially was responsible for most emission increase over the 15-year period. Swedish GHG emissions caused by consumption of animal products reached around 1.1 t CO2e per capita in 2005. The emission cuts necessary for meeting a global temperature-increase target of 2° might imply a severe constraint on the long-term global consumption of animal food. Due to the relatively limited potential for reducing food-related emissions by higher productivity and technological means, structural changes in food consumption towards less emission-intensive food might be required for meeting the 2° target.

Localising livestock protein feed production and the impact on land use and greenhouse gas emissions.

Livestock farmers in Sweden usually grow feed grains for livestock but import protein feed from outside Sweden. Aside from the economic implications, some environmental issues are associated with this practice. We used life cycle assessment to evaluate the impact of local protein feed production on land use and greenhouse gas emissions, compared with the use of imported protein feed, for pig meat and dairy milk produced in Sweden. Our results showed that local production reduced greenhouse gas emissions by 4.5% and 12%, respectively, for pigs and dairy cows. Land use for feed production in Sweden increased by 11% for pigs and 25% for dairy cows, but total land use decreased for pig production and increased for dairy milk production. Increased protein feed cultivation in Sweden decreased inputs needed for animal production and improved some ecological processes (e.g. nutrient recycling) of the farm systems. However, the differences in results between scenarios are relatively small and influenced to an extent by methodological choices such as co-product allocation. Moreover, it was difficult to assess the contribution of greenhouse emissions from land use change. The available accounting methods we applied did not adequately account for the potential land use changes and in some cases provided conflicting results. We conclude that local protein feed production presents an opportunity to reduce greenhouse gas emissions but at a cost of increasing land occupation in Sweden for feed production.

Biomass for energy, food and materials in an industrial society of 10 billion people

In this paper we analyse the requirements of bioproductive land in a future industrial society of 10 billion people, with an average per capita economic standard comparable to that of the industrialized countries of today. Despite significantly more efficient technology, lowering demand for both energy and material per service delivered, requirement for food and material alone will call for a heavily increased demand for bioproductive land for use in agriculture and forestry. Large areas of short rotation energy plantations may be biophysically possible, but will clearly compete for available bioproductive land with agriculture and silviculture, as well as with preservation of the worlds biodiversity. Therefore, the notion that there exists large areas of surplus or degraded land, which, without coming in conflict with food production and preservation of biodiversity, can be used for large energy plantations has not fully taken into account possible increased demand for bioproductive land from global industrialization and the raising of the global average economic standard.

Quantification of uncertainties in global grazing systems assessment

Livestock systems play a key role in global sustainability challenges like food security and climate change, yet, many unknowns and large uncertainties prevail. We present a systematic, spatially explicit assessment of uncertainties related to grazing intensity (GI), a key metric for assessing ecological impacts of grazing, by combining existing datasets on a) grazing feed intake, b) the spatial distribution of livestock, c) the extent of grazing land, and d) its net primary productivity (NPP). An analysis of the resulting 96 maps implies that on average 15% of the grazing land NPP is consumed by livestock. GI is low in most of worlds grazing lands but hotspots of very high GI prevail in 1% of the total grazing area. The agreement between GI maps is good on one fifth of the worlds grazing area, while on the remainder it is low to very low. Largest uncertainties are found in global drylands and where grazing land bears trees (e.g., the Amazon basin or the Taiga belt). In some regions like India or Western Europe massive uncertainties even result in GI > 100% estimates. Our sensitivity analysis indicates that the input-data for NPP, animal distribution and grazing area contribute about equally to the total variability in GI maps, while grazing feed intake is a less critical variable. We argue that a general improvement in quality of the available global level datasets is a precondition for improving the understanding of the role of livestock systems in the context of global environmental change or food security.

Policy Strategies for a Sustainable Food System: Options for Protecting the Climate

How to raise livestock--and how not to / Colin Tudge -- The water footprint of animal products / Arjen Hoekstra -- Livestock and climate change / Tara Garnett -- Industrial livestock production and biodiversity / Susanne Gura -- Does organic farming offer a solution? / Richard Young -- Food from the dairy--husbandry regained? / John Webster -- Cracking the egg / Ian Duncan -- Cheap as chicken / Andy Butterworth -- Sustainable pig production : finding solutions and making choices / Alistair Lawrence and Alistair Stott -- Industrial animal agricultures role in the emergence and spread of disease / Michael Greger -- Environmentally sustainable and equitable meat consumption in a climate change world / A.J. McMichael and Ainslie Butler -- How much meat and milk is optimal for health? / Mike Rayner and Peter Scarborough -- Developing ethical, sustainable and compassionate food policies / Kate Rawles -- Religion, culture and diet / Martin Palmer -- Policy strategies for a sustainable food system: options for protecting the climate / Stefan Wirsenius and Fredrik Hedenus -- Meat and policy : charting a course through the complexity / Tim Lang, Michelle Wu and Martin Caraher -- Confronting policy dilemmas / Jonathon Porritt.In this chapter we argue that in order to substantially reduce greenhouse gas (GHG) emissions from food production and to preserve natural and agricultural biodiversity, policies that separately address the demand and the supply sides of the food system will be required. Taxes on animal food, and other policies that shift consumption patterns towards less GHG intensive and land-demanding food, will be crucial for reducing agricultural GHG emissions as well as for mitigating biodiversity losses related to the expansion of agriculture into natural ecosystems. Demand-moderating policies are vital because of the overall low potential for reducing agricultural GHG emissions by technological means, and because of the inherently large land requirements of ruminant meat (beef and lamb) production. However, demand-side policies alone are far from enough. Comprehensive supply-side policies will also be required, especially for containing agricultural land expansion in order to protect biodiversity in tropical regions. Supply-side policies, such as direct subsidies, will also be fundamental for preserving agricultural-related biodiversity in Europe and other regions holding biodiversity-rich permanent pastures. The latter holds for Europe even if no policies that moderate the demand for ruminant meat are put in place, since the low-intensive land use characteristic of these areas in either case is not economically viable in the long run. Furthermore, the biodiversity rich areas represent a minor share of the total agricultural land in Europe. Therefore, the goal to preserve agricultural biodiversity in Europe should not be taken as a counter-argument against reducing global ruminant meat production by the implementation of demand-moderating policies.

An environmental tax-shift with indirect desirable effects

Imposing environmental taxation on external costs of energy will not only affect the environmental impact of the energy sector itself, but it will tend to decrease environmental damage from other sectors of the economy as well. We have assessed the effects of a shift of taxation from taxing labour to taxation of external costs caused in the energy sector. Several examples give results compatible with the hypothesis that the changing price relation between labour and energy resulting from such a tax shift will make re-use, repairs and recycling increasingly competitive and thus tend to decrease mining as well as waste production. Likewise, less energy-intensive commodities and services in general would become increasingly competitive, and would tend to decrease the environmental load further. These environmentally desirable effects are beyond the taxed external effects of the energy sector itself and occur as an indirect effect of the increased relative price of energy.

A regionalized biophysically based model for the turnover of biomass and enteric methane emissions in the global food system

We have developed an extensive model for the turnover of biomass in the global food system. The turnover is driven by the (human) food intake and the necessary primary production above ground of major crops from arable land and pasture is calculated by an extensive physical modelling from harvest to food (energy and materials turnover). The model will be used to calculate the global emissions of methane from enteric fermentation, today, as well as under various possible scenarios for the agricultural sector. A preliminary estimate of the global methane emissions from enteric fermentation in domestic animals for the years 1992–94 is 110 Tg/y.