A1 Storyline and Scenario Family
The A1 storyline is a case of rapid and successful economic development, in which regional averages of income per capita converge: current distinctions between "poor" and "rich" countries eventually dissolve. The primary dynamics are a strong commitment to market-based solutions; high savings and commitment to education at the household level; high rates of investment and innovation in education, technology and institutions at the national and international level; and international mobility of people, ideas and technology. The transition to economic convergence results from advances in transport and communication technology, shifts in national policies on immigration and education, and international cooperation in the development of national and international institutions that enhance productivity growth and technology diffusion
In this scenario, demographic and economic trends are closely linked, as affluence is correlated with long life and small families (low mortality and low fertility). Global population grows to some nine billion by 2050 and declines to about seven billion by 2100. Average age increases, with the needs of retired people met mainly through their accumulated savings in private pension systems.
The global economy expands at an average annual rate of about three percent to 2100. This is approximately the same as average global growth since 1850, although the conditions that lead to a global economic in productivity and per capita incomes are unparalleled in history. Income per capita reaches about US$21,000 by 2050. While the high average level of income per capita contributes to a great improvement in the overall health and social conditions of the majority of people, this world is not without its problems. In particular, many communities could face some of the problems of social exclusion encountered by the wealthiest countries in the 20th century and in many places income growth could come with increased pressure on the global commons.
Energy and mineral resources are abundant in this scenario family because of rapid technical progress, which both reduce the resources need to produce a given level of output and increases the economically recoverable reserves. Final energy intensity (energy use per unit of GDP) decreases at an average annual rate of 1.3 percent.
Several variant scenarios have been considered in A1 scenario family reflecting the uncertainty in development of energy sources and conversion technologies in this rapidly changing world. Near-term investment decisions may introduce long-term irreversibilities into the market, with lock-in to one technological configuration or another. The A1 marker scenario is based on a balanced mix of energy sources and has an intermediate level of CO2 emissions, but depending on the energy sources developed, emissions in the variants cover a very wide range. In the fossil-fuel intensive variants, emissions approach those of the A2 scenarios; conversely in variants with low labor productivity or of rapid progress in "post-fossil" energy technologies, emissions are intermediate between those of B1 and B2. These variants are not presented separately on the Open Process web site but will be described in the SRES final report. It should be noted that similar variants could equally have applied to other storylines. They have been introduced into the A1 storyline because of its "high growth with high tech" nature, where differences in alternative technology developments translate into large differences in future GHG emission levels
Ecological resilience is assumed to be high in this storyline. Environmental amenities are viewed in a utilitarian way, based on their influence on the formal economy. The concept of environmental quality might change in this storyline from "conservation" of nature to active "management" – and marketing – of natural and environmental services.
With the rapid increase in income, dietary patterns shift initially significantly towards increased consumption of meat and dairy products, but may decrease subsequently with increasing emphasis on health of an aging society. High incomes also translate into high car ownership, sprawling suburbanization and dense transport networks, nationally and internationally. Land prices increase faster than income per capita. These factors along with high wages result in a considerable intensification of agriculture (see also A1 marker scenario description).
A2 Storyline and Scenario Family
In this world the main emphasis is on a strengthening of regional and local culture, with a "return to family values" in many regions. The A2 world "consolidates" into a series of roughly continental economic regions, emphasizing local cultural roots. In some regions, increased religious participation leads many to reject a materialist path and to focus attention on contributing to the local community. Elsewhere, the trend is towards increased investment in education and science and growth in economic productivity. Social and political structures diversify, with some regions moving towards stronger welfare systems and reduced income inequality, while others move towards "lean" government. Environmental concerns are relatively weak, although some attention is paid to bringing local pollution under control and maintaining local environmental amenities.
The A2 world sees more international tensions and less cooperation than in A1 or B1. People, ideas and capital are less mobile so that technology diffuses slowly. International disparities in productivity, and hence income per capita, are maintained or increased. With the emphasis on family and community life, fertility rates decline only slowly, although they vary among regions. Hence, this scenario family has high population growth (to 15 billion by 2100) with comparatively low incomes per capita relative to the A1 and B1 worlds, at US$7,000 in 2050.
Technological change is rapid in some regions and slow in others as industry adjusts to local resource endowments, culture, and education levels. Regions with abundant energy and mineral resources evolve more resource intensive economies, while those poor in resources place very high priority on minimizing import dependence through technological innovation to improve resource efficiency and make use of substitute inputs. The fuel mix in different regions is determined primarily by resource availability. And divisions among regions persist in terms of their mix of technologies, with high-income but resource-poor regions shifting toward advanced post fossil technologies (renewables in regions of large land availability, nuclear in densely populated, resource poor regions) and low-income resource-rich regions generally relying on older fossil technologies.
With substantial food requirements, agricultural productivity is one of the main focus areas for innovation and RD&D efforts in this future. Initially high levels of soil erosion and water pollution are eventually eased through the local development of more sustainable high-yield agriculture.
Although attention is given to potential local and regional environmental damage, it is not uniform across regions. For example, sulfur and particulate emissions are reduced in Asia due to impacts on human health and agricultural production but increase in Africa as a result of the intensified exploitation of coal and other mineral resources. The A2 world sees high energy and carbon intensity, and correspondingly high GHG emissions. Its CO2 emissions are the highest of all four scenario families.
The regionally diverse nature of the A2 scenario family means that many more variants are possible than in A1 or B1. However, this diversity is extremely difficult to capture in global energy, economic and climate models which would need to be specified in great detail at the regional level. Hence, no scenario variants have been proposed for this storyline (see also A2 marker scenario description).
B1 Storyline and Scenario Family
The central elements of this future are a high level of environmental and social consciousness combined with a globally coherent approach to sustainable development with particular emphasis on managing the global commons, apart from climate. Heightened environmental consciousness might be brought about by clear evidence that impacts of natural resource use such as deforestation, soil depletion, overfishing, and global and regional pollution pose a serious threat to the continuation of human life on Earth.
Economic development is balanced, and efforts to achieve equitable income distribution are effective. Like A1, the B1 storyline describes a fast-changing and convergent world, but the priorities differ. Where the A1 world invests its gains from increased productivity and know-how primarily in further economic growth, the B1 world's invests a large part of its gains in improved efficiency of resource use ("dematerialization"), equity, social institutions, and environmental protection.
A strong welfare net prevents social exclusion on the basis of poverty. However, countercurrents may develop and in some places people may not conform to the main social and environmental intentions of the mainstream in this scenario family.
Particular effort is devoted to increasing resource efficiency. Comprehensive incentive systems, combined with advances in international institutions, permit the rapid diffusion of cleaner technology. RD&D to this end is also enhanced together with education and capacity building for clean and equitable development. Organizational measures are adopted to reduce material wastage, maximizing reuse and recycling. The combination of technical and organizational change yields high levels of material and energy saving as well as reductions in pollution. Labor productivity also improves as a byproduct of these efforts. Variants considered within the B1 family of scenarios include different rates of GDP growth and dematerialization (e.g., energy intensity declines).
The demographic transition to low mortality and fertility occurs at the same rate as in A1 but for slightly different reasons, motivated partly by social and environmental concerns. Global population reaches nine billion by 2050 and declines to about seven billion by 2100. This is a world with high levels of economic activity and significant and deliberate progress toward international and national income equality. Global income per capita in 2050 averages US$13,000; somewhat lower than in A1. A higher proportion of this income is spent on services rather than on material goods, and on quality rather than quantity, because of less emphasis on material goods and also higher resource prices.
The B1 storyline sees a relatively smooth transition to alternative energy systems as conventional oil resources decline. There is extensive use of conventional and unconventional gas as the cleanest fossil resource during the transition, but the major push is towards post fossil technologies driven in large part by environmental concerns.
Given the high environmental consciousness and institutional effectiveness in the B1 storyline, environmental quality is high, as most potentially negative environmental aspects of rapid development are anticipated and dealt with effectively locally, nationally, and internationally. For example, transboundary air pollution (acid rain) is basically eliminated in the long-term. Land-use is carefully managed to counteract the impacts of activities potentially damaging to the environment. Cities are compact and designed for public and non-motorized transport, with suburban developments tightly controlled. Strong incentives for low-input, low-impact agriculture along with maintenance of large areas of wilderness contribute to high food prices with much lower levels of meat consumption than those in A1. These proactive local and regional environmental measures and policies also lead to relatively low GHG emissions even in the absence of explicit interventions directed at mitigating climate change (see also B1 marker scenario description).
B2 Storyline and Scenario Family
Like B1, theB2 world is one of increased concern for environmental and social sustainability, but the character of this world differs substantially. Government policies and business strategies at the national and local level are increasingly influenced by environmentally aware citizens, with a trend towards local self-reliance and stronger communities. International institutions decline in importance with the shift towards local decision-making structures and institutions. Human welfare, equality, and environmental protection all have high priority, and they are addressed through community-based, social solutions in addition to technical solutions, albeit implementation rates vary across regions
Education and welfare programs are widely pursued leading to reductions in mortality and, to a lesser extent, fertility. The population reaches about 10 billion people by 2100, consistent with both the United Nations and IIASA median projections. Income per capita grows at an intermediary rate to reach about US$12,000 by 2050. International income differences decrease, although not as rapidly as in scenarios of higher global convergence (A1, B1). Local inequity is reduced considerably through the development of stronger community support networks.
Generally high educational levels promote both development and environmental protection. Indeed, environmental protection is one of the few remaining truly international priorities. However, strategies to address global environmental challenges are less successful than in B1, as governments have difficulty designing and implementing agreements that combine environmental protection with mutual economic benefits.
The B2 storyline presents a particularly favorable climate for community initiative and social innovation, especially in view of high educational levels. Technological frontiers are pushed less than in A1 and B1 and innovations are also regionally more heterogeneous. Globally investment in RD&D continues its current declining trend, and mechanisms for international diffusion of technology and know-how remain weaker than in scenarios A1 and B1 (but higher than in scenario A2). Some regions with rapid economic development and limited natural resources place particular emphasis on technology development and bilateral co-operation. Technical change is therefore uneven. The primary energy intensity of GWP declines at about one percent per year, in line with the average historical experience of the last two centuries.
Land-use management becomes better integrated at the local level in the B2 world. Urban and transport infrastructure is a particular focus of community innovation, contributing to a low level of car dependence and less urban sprawl. An emphasis on food self-reliance contributes to a shift in dietary patterns towards local products, with reduced meat consumption in countries with high population densities.
Energy systems differ from region to region, depending on the availability of natural resources. The need to use energy and other resources more efficiently spurs the development of less carbon-intensive technology in some regions. Environment policy cooperation at the regional level leads to success in the management of some transboundary environmental problems, such as acidification due to SOx, especially to sustain regional self-reliance in agricultural production. Regional cooperation also results in lower emissions of NOx and VOCs, reducing the incidence of elevated tropospheric ozone levels. Although globally the energy system remains predominantly hydrocarbon-based to 2100, there is a gradual transition away from the current share of fossil resources in world energy supply, with a corresponding reduction in carbon intensity (see also B2 marker scenario description).