text: Ecosystem Change: 5. How might ecosystems and their services change in the future under various plausible scenarios?
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  Four plausible scenarios explore the future of ecosystems and human well-being for the next 50 years and beyond. The scenarios consider two possible paths of world development: increasing globalization or increasing regionalization. They also consider two different approaches to ecosystem management: in one approach, actions are reactive and address problems only after they become obvious, in the other approach, ecosystem management is proactive and deliberately aims for long-term maintenance of ecosystem services. More...
  5.1.1 The four scenarios are:
  Global Orchestration - This scenario depicts a globally-connected society that focuses on global trade and economic liberalization and takes a reactive approach to ecosystem problems. However, it also takes strong steps to reduce poverty and inequality and to invest in public goods such as infrastructure and education. In comparison to the other scenarios, this scenario has the highest economic growth while it assumes the smallest population in 2050.
  Order from Strength - This scenario represents a regionalized and fragmented world, concerned with security and protection, emphasizing primarily regional markets, paying little attention to public goods, and taking a reactive approach to ecosystem problems. In comparison to the other scenarios, economic growth rates are the lowest (particularly low in developing countries) and decrease with time, while population growth is the highest.
  Adapting Mosaic - In this scenario, regional watershed-scale ecosystems are the focus of political and economic activity. Local institutions are strengthened and local ecosystem management strategies are common, and societies develop a strongly proactive approach to the management of ecosystems. Economic growth rates are somewhat low initially but increase with time, and the population in 2050 is nearly as high as in the Order from Strength scenario.
  TechnoGarden - This scenario depicts a globally connected world relying strongly on environmentally sound technology, using highly managed, often engineered, ecosystems to deliver ecosystem services, and taking a proactive approach to the management of ecosystems in an effort to avoid problems. Economic growth is relatively high and accelerates, while population in 2050 is in the mid-range of the scenarios.
  Further information about each scenario is provided in the links below:
  5.1.2 The scenarios are not predictions, but explore possible future changes in ecosystem services and socio-economic factors. No scenario represents business-as-usual, though all begin from current conditions and trends. The actual future is likely to consist of a mix of approaches and consequences described in the scenarios, as well as events and innovations that have not yet been imagined. No scenario will match the future as it actually occurs. Other scenarios could be developed with either more optimistic or more pessimistic outcomes for ecosystems, their services, and human well-being. More...
  5.2.1 In the four scenarios, ecosystems are affected by the same set of indirect and direct drivers as today, but the relative importance of different drivers is projected to change over the next 50 years. Factors such as global population growth will become relatively less important and other factors (for instance the distribution of people, climate change, and changes to nutrient cycles) will grow in importance.
  See: Table 5.1 on the main assumptions of the different scenarios
  on future changes in different indirect and direct drivers
  Projections from 2000 to 2050 under all the four scenarios:
  World population is projected to reach between approximately 8.1 and 9.6 billion people in 2050 (and between 6.8 and 10.5 billion in 2100), depending on the scenario (see figure 5.1).
  Per capita income is projected to increase two- to four-fold, depending on the scenario, leading to increased consumption.
  Land use change, particularly the expansion of agriculture, is projected to stay a major direct driver of change both on land and in rivers and lakes.
  High nutrient levels in water (nutrient loading) is projected to become an increasing problem, particularly in developing countries. At present, major impacts include growth of toxic algae, health problems, fish kills, and damage to coral reefs.
  Climate change effects on biodiversity and ecosystem services are projected to increase. Changes are expected at least in temperature, precipitation, vegetation, sea level, and the frequency of extreme weather events.
  Compared to other estimates of climate change (see, for example, the estimates of the IPCC 3rd Assessment report) these estimates are in the low to middle range, partly because the four scenarios assume that significant action will be taken against climate change by the middle of the 21st century. An increase in global average precipitation is predicted, but some areas will become drier, others wetter.
  Ecosystem services will be directly altered by climate change through changes in productivity and growing zones of vegetation, and through changes in the frequency of extreme weather events. Moreover, climate change is predicted to affect ecosystems indirectly, for example through sea level rise affecting shoreline vegetation.
  A series of ecosystem services identified as key development challenges are expected to be adversely affected by climate change. These include providing clean water, energy services, and food, maintaining a healthy environment, as well as conserving ecological systems, their biodiversity, and associated ecological goods and services.
  By 2100, climate change and its impacts may become the dominant direct drivers of biodiversity loss and change of ecosystem services globally. Though some ecosystem services in some regions may initially benefit from predicted increases in temperature or precipitation, a significant net harmful impact on ecosystem services worldwide is expected once the temperature reaches 2°C above pre-industrial levels or warming increases by more than 0.2°C per decade. More...
  5.3.1 Rapid conversion of ecosystems is projected to continue under all four scenarios. Roughly 10 to 20% of current grassland and forest areas are expected to be converted for the expansion of agriculture, cities, and infrastructure. How quickly ecosystems will be converted is highly dependent on future changes in population, wealth, trade, and technology. Habitat loss on land will lead to a sharp decline in local diversity of native species and related services in all four scenarios by 2050.
  The habitat losses projected in the four scenarios will lead to global extinctions as populations adjust to the remaining habitat. The number of plant species, for example, could drop by 10-15% as a result of habitat lost between 1970 and 2050. Some species will be lost immediately when their habitat is modified but others may persist for decades or centuries. Time lags between habitat reduction and extinction provide an opportunity for humans to restore habitats and rescue species from extinction. More...
  See: Table 5.2 on the outcomes of scenarios for ecosystem services
  in 2050 Compared with 2000
  When comparing provisioning, regulating, and cultural services available to humans today and in 2050, all the scenarios except the "Order from Strength" scenario lead to net improvements in at least one of the service categories. However, even in scenarios showing improvements, biodiversity loss continues rapidly (see figure 5.3). More...
  5.4.1 The following changes to ecosystem services and human well-being were common to all the four scenarios:
  Human use of ecosystem services increases substantially. In many cases, this leads to a deterioration in the quality of services, and even a reduction in quantity if the use is unsustainable. Growing population and per capita consumption increase the demand for services, even though resource use is increasingly efficient.
  Food security is likely to remain out of reach for many people, despite increasing food supply and more varied diets in poor countries.
  World freshwater resources are projected to go through vast and complex changes, with great geographic variability. Increased precipitation due to climate change will make more water available in some areas, but will also increase the frequency of flooding. In other areas decreases in precipitation will make less water available. In addition, water withdrawals and wastewater discharges are expected to increase substantially in some developing regions.
  Growing demand for fish leads to an increasing risk of collapse of regional marine fisheries. Aquaculture may relieve some of this pressure, but would have to stop relying on marine fish as a feed source.
  5.4.2 The future contribution of terrestrial ecosystems to the regulation of climate is uncertain. Carbon release or uptake by ecosystems affects the amount of certain greenhouse gases in the atmosphere and thus regulates world climate. Currently, ecosystems are a net sink of carbon, absorbing about 20% of fossil fuel emissions. This climate regulating service is very likely to be affected by changes in land use, although predictions are difficult to make because of our limited understanding of soil respiration processes. More...
  5.4.3 Dryland ecosystem services are especially vulnerable to changes, particularly those due to climate change, water stress, and intensive use. More...
  5.4.4 Human health improves in the future under most of the scenarios. The number of children affected by undernourishment is reduced, and so are rates of HIV/AIDS, malaria, and tuberculosis. Improved public health measures limit the impact of new diseases such as SARS. However, under the "Order from Strength" scenario, health and social conditions for the North and South could diverge, causing a negative spiral of poverty, declining health, and degraded ecosystems in developing countries. More...
  5.4.5 Each scenario yields a different package of gains, losses, and vulnerabilities to human well-being in different regions and populations. For example, globally-integrated approaches that focus on technology and property rights for ecosystem services generally improve human well-being in terms of health, security, social relations, and material needs. However, if the same technologies are used globally, local culture can be lost or undervalued. More...
  See: Table 5.3 on the outcomes of scenarios for human well-being
  The scenarios suggest that proactive management of ecosystems is generally advantageous and particularly so under changing or novel conditions. Ecological surprises are inevitable because the interactions involved are complex and because the dynamic properties of ecosystems are currently not well understood. Surprising phenomena of the past century that are now well understood include the ability of pests to become resistant to biocides and the contribution of certain land uses to desertification.
  A proactive approach is more beneficial than a reactive approach, because restoring degraded or collapsed ecosystem services is, if at all possible, more costly and time consuming than preventing degradation. Nevertheless, there are costs and benefits to both proactive and reactive approaches (as shown in Table 5.4).