first generation biofuels. Most assessments also expect high­er energy prices. These higher prices (and possible changes in energy subsidies) are likely to encourage the use of more energy-efficient technologies in agricultural production as well as in processing and distributing food.

8. Existing assessments indicate that while agricul­ture is a major contributor to global environmental change—such as land degradation, nutrient pollution, biodiversity loss, decreasing surface and groundwa-ter availability and climate change—it will also have to adapt to these changes. Assessments indicate an in­creased demand for water from the non-agricultural sectors, which could further exacerbate water limitations already felt by developing country farmers. Increasing rates of land degradation in many regions may limit the ability of agricul­ture systems to provide food security. Business-as-usual sce­narios indicate a further increase in the already substantial negative contribution of agriculture in global environmental change. However, alternative scenarios highlight that there are also many opportunities for enhancing the positive role of agriculture in providing ecosystem services and minimiz­ing its environmental impacts.

9. Existing assessments expect agriculture to increas­ingly be affected by global warming and changes in climate variability. For agriculture, changes in seasonal variability and extreme events are even more important than changes in mean temperature and precipitation. Re­cent studies, such as presented in IPCC's Fourth Assessment Report, indicate that negative impacts on agriculture tend to concentrate in low income regions. In temperate regions impacts could result in net positive yields. Developments in AKST will determine the capacity of food systems to re­spond to the likely climate changes. Agriculture is also a source of greenhouse gas emissions and therefore agricul­ture can play a significant role in mitigation policies. In or­der to play this role, new AKST options for reducing net emissions of carbon dioxide, methane and nitrous oxide need to be developed.

10. Trends observed over the last decade, as described in existing assessments, show that the share of em­ployment in agriculture is declining and this emerging trend is expected to continue. The expected increase in urbanization and international labor migration as well as better working conditions in other sectors will catalyse a labor shift away from agriculture to other sectors. Agricul­tural labor productivity is expected to increase as a result of improved mechanisation and developments in AKST that are responsive to emerging agricultural and food systems.

11. There is a trend in many regions to reduce invest­ment in traditional agricultural disciplines in favor of emerging research areas such as plant and microbial molecular biology, information technology and nano-technology. Investment in AKST is increasingly less driven by the needs of agriculture per se, but is a spin-off of other research priorities such as human health and security. These investments mainly occur in industrialized countries and advanced developing countries and the products may not

be easily accessible and applicable to least developing coun­tries. To effectively apply advances in the emerging research areas to diverse agriculture systems requires knowledge gen­erated in the traditional agricultural disciplines. The effect of the shift in investments on AKST is not fully explored.

4.1 Driving Forces of Agricultural Change

Changes in agriculture are a result of the developments of a range of underlying driving forces—both direct and indi­rect—and their many interactions. Previous chapters have described past agricultural changes in general, and change in agricultural knowledge, science and technology (AKST) in particular, in their political, economic, social, cultural, environmental contexts  (Global Chapters  1-3). This as­sessment presents a conceptual framework to structure the analysis of agriculture and development towards reaching sustainability goals. This framework highlights that agricul­ture, although a central focus of this assessment, needs to be seen as part of a larger societal context and is dynamically linked to many other human activities. Changes in these activities can both directly and indirectly drive change in agriculture (Figure 4-1).
     Driving forces or drivers are those factors that directly or indirectly induce changes in the agricultural system. A direct driver unequivocally influences agricultural produc­tion and services and can therefore be identified and mea­sured with differing degrees of accuracy. An indirect driver operates more diffusely, often by altering one or more direct drivers, and its influence is established by understanding its effect on a direct driver. When assessing past developments and the prospects for future changes in agricultural systems and the role of AKST, it is crucial to understand the cur­rent trends in the driving forces that shape the agricultural system.
     This chapter gives an overview of current literature on how agriculture and its drivers may change in the future— thus setting the context for looking specifically at how fu­ture agricultural development can be influenced by AKST (Global chapters 5-9). By identifying plausible assumptions on future changes of drivers of agricultural systems, an idea of the most prominent challenges that agriculture might face over the next 50 years emerges, and based on this under­standing, key uncertainties can be distilled. Published out­looks, projections and scenario studies are presented here to give an overview of how some of the most important indi­rect drivers of agricultural changes are expected to unfold, based on current literature and recent international assess­ments—the main indirect drivers discussed in this chapter are:
1.    Demographic developments, including changes in pop­ulation size, age and gender structure, and spatial distri­bution (4.3.1);
2.    Economic and international trade developments, in­cluding changes in national and per capita income, macroeconomic policies, international trade, and capi­tal flows (4.3.2);
3.    Sociopolitical developments, including changes in de­mocratization and international dispute mechanisms (4.3.3);
4.    Scientific and technological developments,  including