Sanderine Nonhebel

Global changes in diets and the consequences for land requirements for food

Provision of food is a prerequisite for the functioning of human society. Cropland where food and feed are grown is the central, limiting resource for food production. The amount of cropland needed depends on population numbers, average food consumption patterns, and output per unit of land. Around the globe, these factors show large differences. We use data from the Food and Agriculture Organization to consistently assess subcontinental dynamics of how much land was needed to supply the prevailing diets during a span of 46 y, from 1961 to 2007. We find that, in most regions, diets became richer while the land needed to feed one person decreased. A decomposition approach is used to quantify the contributions of the main drivers of cropland requirements for food: changes in population, agricultural technology, and diet. We compare the impact of these drivers for different subcontinents and find that potential land savings through yield increases were offset by a combination of population growth and dietary change. The dynamics of the three factors were the largest in developing regions and emerging economies. The results indicate an inverse relationship between the two main drivers behind increased land requirements for food: with socioeconomic development, population growth decreases and, at the same time, diets become richer. In many regions, dietary change may override population growth as major driver behind land requirements for food in the near future.

Consumption patterns and their effects on land required for food

Abstract Vast amounts of land are required for the production of food, but the area suitable for growing crops is limited. In this paper, attention is paid to the relationship between food consumption patterns and agricultural land requirements. Land requirements per food item that were determined in a previous study are combined with data on the per capita food consumption of various food packages, varying from subsistence to affluent, leading to information on land requirements for food. Large differences could be shown in per capita food consumption and related land requirements, while food consumption, expenditure, and the physical consumption of specific foods change rapidly over time. A difference of a factor of two was found between the requirements for existing European food patterns, while the land requirement for a hypothetical diet based on wheat was six times less than that for an existing affluent diet with meat. It is argued that in the near future changes in consumption patterns rather than population growth will form the most important variable for total land requirements for food. Trends towards the consumption of foods associated with affluent lifestyles will bring with them a need for more land. Lifestyle changes, changes in consumer behavior on a household level, can be considered as powerful options to reduce the use of natural resources such as agricultural land.

Greenhouse gas emissions related to Dutch food consumption

The consumption of food products involves emissions of greenhouse gases. Emissions occur in the various stages of the life cycle of food products. In this paper we discuss the greenhouse gas emissions, CO2, CH4, and N2O, related to Dutch household food consumption. Combinations of greenhouse gas intensities (per Dfl) with annual household expenditures results in the greenhouse gas emissions from annual food consumption. An energy analysis methodology is elaborated with greenhouse gas emissions to calculate greenhouse gas intensities. The CO2 emission pattern resembles closely the household expenditure pattern. Emission patterns of CH4 and N2O differ strongly from the expenditure pattern. Food products from cattle farming determine the CH4 emissions, while food products from agriculture determine the N2O emissions. The non-CO2 greenhouse gases contribute 25% to the total emissions of CO2 equivalents from Dutch household food consumption, significantly above their share in the total Dutch emission of greenhouse gases. For food product life cycles it is very important to include the non-CO2 greenhouse gases. The analyses show differences in greenhouse gas intensities within food product categories and between food product categories. These differences offer possibilities for reduction options.

Total greenhouse gas emissions related to the Dutch crop production system

Abstract This article discusses the greenhouse gas emissions (CO2, CH4, N2O) related to Dutch agricultural crop production. Emissions occur during agricultural processes (direct emissions) as well as in the life cycle of the required inputs (indirect emissions). An integrated approach assesses the total greenhouse gas emissions related to Dutch agricultural crop production. The results show differences in total greenhouse gas emissions among agricultural crops and in the contribution of separate greenhouse gases to the total emissions.

Food consumption patterns and economic growth. Increasing affluence and the use of natural resources.

This study analyzes relationships between food supply, consumption and income, taking supply, meat and dairy, and consumption composition (in macronutrients) as indicators, with annual per capita GDP as indicator for income. It compares food consumption patterns for 57 countries (2001) and gives time trends for western and southern Europe. Cross-sectional and time series relationships show similar patterns of change. For low income countries, GDP increase is accompanied by changes towards food consumption patterns with large gaps between supply and actual consumption. Total supply differs by a factor of two between low and high income countries. People in low income countries derive nutritional energy mainly from carbohydrates; the contribution of fats is small, that of protein the same as for high income countries and that of meat and dairy negligible. People in high income countries derive nutritional energy mainly from carbohydrates and fat, with substantial contribution of meat and dairy. Whenever and wherever economic growth occurs, food consumption shows similar change in direction. The European nutrition transition happened gradually, enabling agriculture and trade to keep pace with demand growth. Continuation of present economic trends might cause significant pressure on natural resources, because changes in food demand occur much faster than in the past, especially in Asia.

The Effects of Use of Average Instead of Daily Weather Data in Crop Growth Simulation Models

Abstract Development and use of crop growth simulation models has increased in the last decades. Most crop growth models require daily weather data as input values. These data are not easy to obtain and therefore in many studies daily data are generated, or average values are used as input data for these models. In crop growth models non-linear relations often occur. Thus the simulation result with average data can be different from the average result with daily data. In this study the effects of using average weather data on simulated potential and water-limited yields were investigated with a spring wheat crop growth model. It was expected that deviation in simulation results was related to the variability of the weather. Therefore effects were studied for sites in three different climates: temperate maritime, mediterranean and humid tropical. Variability of the weather during the growing season on these sites was quantified. Intuitively the weather in the mediterranean and humid tropical climates is far more constant than the weather in the temperate maritime climates. However, for all locations the variability of the weather during the growing season was nearly the same. The explanation for this unexpected result was found in the fact that on all sites crops were grown in that part of the year in which it rains. The existence of dry and wet days during the growing season causes a large day-to-day variation in weather. For all sites an overestimation of the simulated potential yield of 5–15% was found as a result of using average weather data. For water-limited production the use of average data resulted in overestimation of yield in the wet conditions and underestimation of yield in dry conditions (up to 50%).

Energy yields in intensive and extensive biomass production systems

As for agricultural crops, biomass crops can be grown in intensive production systems (external inputs such as pesticides and artificial fertilisers) or extensive systems with few external inputs. The choice between an intensive or extensive production system has consequences for yields. A method is presented to estimate biomass yields in intensive and/or extensive production systems. This method is applied to a poplar coppice production system. Results of the method are used to evaluate several intensive and extensive production systems with respect to bioenergy yield and fossil fuel use efficiency. The energy yield (GJ/ha) of the intensive systems was highest, while the extensive systems show the better fossil fuel use efficiency (GJ output/GJ fossil energy input).

Effects of Temperature Rise and Increase in CO2 Concentration on Simulated Wheat Yields in Europe

A crop-growth-simulation model based on SUCROS87 was used to study effects of temperature rise and increase of atmospheric CO2 concentration on wheat yields in several regions in Europe. The model simulated potential and water-limited crop production (growth with ample supply of nutrients and in the absence of damage by pests, diseases and weeds). Historic daily weather data from 13 sites in Western Europe were used as starting point.For potential production (optimal water) a 3 °C temperature rise led to a yield decline due to a shortening of the growing period on all locations. Doubling of the CO2 concentration caused an increase in yield of 40% due to higher assimilation rates. It was found that effects of higher temperature and higher CO2 concentration were nearly additive and the combination of both led to a yield increase of 1–2 ton ha-1. A very small CO2-temperature interaction was found: the effect of doubled CO2 concentration on crop yield was larger at higher temperatures. The inter-annual yield variability was hardly affected.When water was limiting crop-production effects of temperature rise and higher CO2 levels were different than for the potential production. Rise in temperature led to a smaller yield reduction, doubled CO2 concentration to a larger yield increase and combination of both led to a large yield increase (3 ton ha-1) in comparison with yields simulated for the present situation. Both rise in temperature and increase in the CO2 concentration reduced water requirements of the crop. Water shortages became smaller, leading to a reduction in inter-annual variability. It is concluded that when no major changes in precipitation pattern occur a climate change will not affect wheat yields since negative effects of higher temperatures are compensated by positive effects of CO2 enrichment.

Replacement of meat and dairy by plant-derived foods: estimated effects on land use, iron and SFA intakes in young Dutch adult females

OBJECTIVE Reduction in the current high levels of meat and dairy consumption may contribute to environmental as well as human health. Since meat is a major source of Fe, effects on Fe intake need to be evaluated, especially in groups vulnerable to negative Fe status. In the present study we evaluated the effects of replacing meat and dairy foods with plant-based products on environmental sustainability (land requirement) and health (SFA and Fe intakes) in women. DESIGN Data on land requirements were derived from existing calculation methods. Food composition data were derived from the Dutch Food Composition Table 2006. Data were linked to the food consumption of young Dutch women. Land requirements and nutrient intakes were evaluated at baseline and in two scenarios in which 30% (Scenario_30%) or 100% (Scenario_100%) of the dairy and meat consumption was randomly replaced by the same amount of plant-based dairy- and meat-replacing foods. SETTING The Netherlands. SUBJECTS Three hundred and ninety-eight young Dutch females. RESULTS Replacement of meat and dairy by plant-based foods benefited the environment by decreasing land use. The intake of SFA decreased considerably compared with the baseline situation. On average, total Fe intake increased by 2.5 mg/d, although most of the Fe intake was from a less bioavailable source. CONCLUSIONS Replacement of meat and dairy foods by plant-based foods reduced land use for consumption and SFA intake of young Dutch females and did not compromise total Fe intake.

Effects of Changes in Temperature and CO2 Concentration on Simulated Spring Wheat Yields in The Netherlands

A crop growth simulation model based on SUCROS87 was constructed to study the effects of temperature rise and increase of the atmospheric CO2 concentration on spring wheat yields in The Netherlands. The model simulated potential production (limited by crop characteristics, temperature and radiation but without any stress from water or nutrient shortages or pests, diseases and weeds) and water-limited production in which growth is also limited by water shortage. The model was validated for the present climatic conditions. When daily weather data from a nearby station were used, the model was well able to simulate yields obtained in field experiments.Effects of several combinations of temperature rise and atmospheric CO2 concentration on simulated yields were studied. A temperature rise resulted in a reduction in simulated yield due to shortening of the growing period. Large variations existed in the magnitude of this reduction. Increases in atmospheric CO2 concentration led to yield increases due to higher assimilation rates and to increase of the water use efficiency. Combination of temperature rise and higher CO2 concentration resulted in small yield increases in years in which water was not limiting growth and large yield increases in dry years.Change of variety or of sowing date could not reduce the negative effects of temperature rise on simulated yields.