CEIL   02670
Unidad Ejecutora - UE
capítulos de libros
Current and future interactions between nature and society
IPBES Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. UNITED NATIONS/FAO
Lugar: Berlin; Año: 2018; p. 538 - 643
Executive summary1. One hundred per cent of the natural units of analysis will continue to be negatively affected, with a concomitant decrease in nature?s contributions to people, given current trends (business as usual), though the magnitude and exact mechanism of the individual drivers will vary by driver and unit of analysis (established but incomplete){5.4}. For example, tropical moist and dry forest and coastal mangroves will continue to exhibit a decline due to land use change regardless of the scenarios considered, but different local factors (agriculturalization and urbanization, respectively) will be involved (well established) {5.4.1, 5.4.11}. Additionally, some drivers will affect units of analysis differently. Empirical evidence indicates differential effects of climate change: boreal forest is extending northward {5.4.2}, while tundra is diminishing in land area (established but incomplete) {5.4.3}. Thus, some drivers, and their relative roles, will need to be further refined on a local scale and with respect to their proximate factors.2. Multiple drivers will act in synergy and further produce biodiversity loss and impact nature?s contributions to people in most of the units of analysis for the Americas (established but incomplete){5.4}. Climate change, combined with other drivers, is predicted to account for an increasingly larger proportion of biodiversity loss in the future, in both terrestrial and aquatic ecosystems {5.3}. Forest fragmentation, climate change and industrial development increase risk of biodiversity and nature?s contributions to people loss i.e. dry forest unit of analysis {}. Predictions on invasive species and climate change indicates an increase in habitable areas and their potential impacts on different units of analysis {5.3}.3. Changes in temperature, precipitation regime and extreme climate events are predicted to impact all units of analysis in the Americas (well established) {5.4}. Climate change and the potential impacts on tropical dry forests by changing the frequency of wildfires; change in forest structure and functional composition in the Amazon tropical moist forest; extreme drought events changing nature?s contributions to people in the Amazon region; insect outbreaks and changes in albedo are predicted to significantly impact temperate, boreal and tundra units of analysis, affecting society and indigenous communities and well-being {5.4}.4. Thresholds, or tipping points (conditions resulting in rapid and potentially irreversible changes) may have already been exceeded for some ecosystems and are likely for others (established but incomplete). For instance, it is considered more likely than not that such a threshold has already been passed in the cryosphere with respect to summer sea ice (established but incomplete) {5.4.12}. Model simulations indicate changes in forest structure and species distribution in the Amazon forest in response to global warming and change in precipitation patterns (forest die-back) (established but incomplete) {5.4.1}. So too, a 4oC increase in global temperatures is predicted to likely cause widespread die off of boreal forest due to greater susceptibility to disease {5.4.2} and global temperature increases may have already started persistent thawing of the permafrost {5.4.3}. Under 4°C warming, widespread coral reef mortality is expected with significant impacts on coral reef ecosystems {5.4.11}. Sea surface water temperature increase will cause a reduction of sea grass climatic niche: those populations under seawater surface temperature thresholds higher than the temperature ranges required by the species could become extinct by 2100 with concomitant loss of ecosystem services.IPBES/6/INF/4/Rev.15415. Changes in nature and nature?s contributions to people in most units of analysis are increasingly driven by causal interactions between distant places (i.e. telecouplings) (well established) {5.6.3}, thus scenarios and models that incorporate telecouplings will better inform future policy decisions. Nature and nature?s contributions to people in telecoupled systems can be affected negatively or positively by distant causal interactions. Provision of food and medicine from wild organisms in temperate and tropical grasslands, savannas and forests of South America is being dramatically reduced due to land-use changes driven by the demand of agricultural commodities (e.g. soybeans) mainly from Europe and China. Conservation of insectivorous migratory bats in Mexico benefits pest control in agroecosystems of North America, resulting in increased yields and reduced pesticide costs. Trade policies and international agreements will thus have an increasingly strong effect on environmental outcomes in telecoupled systems.6. Policy interventions have resulted in significant land use changes at the local and regional scales and will continue to do so through 2050. These policies have affected nature?s contributions to people both positively and negatively, and provide an opportunity to manage trade-offs among nature?s contributions to people (well established) {5.4}. Land use changes are now mainly driven by high crop demand, big hydropower plans, rapid urban growth and result in a continued loss of grasslands {5.4.4, 5.4.5}. However, strategies for establishing conservation units have helped in reducing deforestation in the Brazilian Amazon from the period of 2004 to 2011 (well established) {5.4.1}. Similarly, wetland protection policies and regulation have helped reduce the conversion of wetlands in North America {5.4.7}. Policies based on command and control measures may be limited in providing effective reduction in ecosystem loss and should be complemented with policies acknowledging multiple values {5.6.3}.7. Policy interventions at vastly differing scales (from national to local) lead to successful outcomes in mitigating impacts to biodiversity (established but incomplete){5.4}. For instance, long-established governmental protections of wetlands in North America have significantly slowed and may have stopped wetland loss based on acreage {5.4.7}. In South America, where mangrove loss continues at a rate of one to two per cent, different stakeholders such as local communities and/or governments have been successful in protecting mangroves based on empowerment and shared interests in their preservation {5.4.11}.8. Pressures to nature are projected to increase by 2050, negatively affecting biodiversity as indicated by a potential reduction of the mean species abundance index. However, the magnitude of the pressures by 2050 are expected to be less under transition pathways to sustainability in comparison to the business as usual scenario (established but incomplete), {5.5}. The Global Biodiversity model projected that under the business as usual scenario mean species abundance had decreased in the Americas by approximately 30 per cent by 2010 compared to its values prior to European settlement of the New World, with historical losses primarily attributed to land transformation to agricultural uses. Using the Global Biodiversity model, there is an additional projected loss of 9.6 per cent by 2050, primarily attributed to some additional land use changes , and especially to climate change, which will steadily increase relative to other drivers considered in the model. However, under the transition pathways to sustainability of global technologies, decentralised solutions, and consumption change pathways, the projected losses are 6 per cent, 5 per cent, and 5 per cent, respectively,IPBES/6/INF/4/Rev.1542achieving a relative improvement of approximately 30 per cent to 50 per cent compared to the business as usual scenario. Under these pathways, climate change mitigation, the expansion of protected areas and the recovery of abandoned lands would significantly contribute to reducing biodiversity loss.9. Participative scenarios have proven to be a successful tool for envisioning potential futures and pathways and to embrace and integrate multiple and sometime conflicting values and their role in promoting bottom-up decision making in the face of future?s uncertainties (well established) {5.3}. The use of participative approaches to develop scenarios has increased during recent years in the Americas. The inclusion of different stakeholders and their knowledges in the process of constructing potential futures has promoted a better understanding of the complexity of the social-ecological systems in which they are embedded. This has enhanced co-learning processes between all actors involved, even those normally under-represented in decision-making activities. As a result, several participative scenario exercises have motivated community-based solutions and local governance initiatives all pointing towards the development of adaptive management strategies {5.3}.10. Pathways that consider changes in societal options will lead to less pressure to nature (established but incomplete) {5.6.3}. An example is the indirect impact that shifts in urban dietary preferences have on agricultural production and expansion, and food options that are expected to continue growing into the future. Therefore, not only is there a strong connection between urbanization and economic growth, but also between affluence (and urban preferences) and the global displacement of land use particularly from high-income to low-income countries.11. Available local studies informing regional futures of nature and nature?s benefit to people do not allow scalability as of yet (well established) {5.3}. The challenge in expanding the findings from local studies resides in the fact that a number of comparable local studies are still not available. Information is scattered throughout the region by the use of different units, methods and scales, which prevents a local-to-regional generalization. The list of ?nature? indicators used in studies at local scales is large and heterogeneous (well established). Even for the same indicator (e.g. biodiversity), different metrics are used (e.g. species-area curve, mean species abundance) {5.5}. In other cases, multiple indicators are used to describe different aspects of biodiversity and ecosystem services. In this latter case, synergies and trade-offs are explicitly mentioned with a clear pattern in which increasing the provision of some indicators result in the detriment of others {5.3}. For example, agriculture expansion leading to loss in biodiversity illustrates a common trend from local studies expected to continue into the future.12. There is a significant research gap in the development of models and scenarios that integrate drivers, nature, nature?s contributions to people and good quality of life (well established){5.3}. Models and scenarios can be powerful tools to integrate and synthesize the complex dynamics of coupled human and nature systems, and to project their plausible behaviors into the future. Most existing models and scenarios focus on the link between drivers and its impacts on nature. Few cases exist in which models or scenarios integrate the relationships between changes in nature and changes in nature?s contributions to people and good quality of life {5.3}. Inter-and trans-disciplinary modeling efforts will be required to address this research gap {5.3}.