Mobility restrictions-trade and travel bans, border closures and, in extreme cases, area quarantines or cordons sanitaires-are among the most widely used measures to control infectious diseases. ...Restrictions of this kind were important in the response to epidemics of SARS (2003), H1N1 influenza (2009), Ebola (2014) and, currently in the containment of the ongoing COVID-19 pandemic. However, they do not always work as expected.
To determine when mobility restrictions reduce the size of an epidemic, we use a model of disease transmission within and between economically heterogeneous locally connected communities. One community comprises a low-risk, low-density population with access to effective medical resources. The other comprises a high-risk, high-density population without access to effective medical resources.
Unrestricted mobility between the two risk communities increases the number of secondary cases in the low-risk community but reduces the overall epidemic size. By contrast, the imposition of a cordon sanitaire around the high-risk community reduces the number of secondary infections in the low-risk community but increases the overall epidemic size.
Mobility restrictions may not be an effective policy for controlling the spread of an infectious disease if it is assessed by the overall final epidemic size. Patterns of mobility established through the independent mobility and trade decisions of people in both communities may be sufficient to contain epidemics.
This special issue results from a call for papers to address the connection between resilience and sustainability, and stems from the fact that the ecological concept of resilience has been ...exercising an increasing influence on the economics of development. Resilience is interpreted in two different ways by ecologists: one capturing the speed of return to equilibrium following perturbation (Pimm, 1984), the other capturing the size of a disturbance needed to dislodge a system from its stability domain (Holling, 1973). The latter may be interpreted as the conditional probability that a system in one stability domain will flip into another stability domain given its current state and the disturbance regime (Perrings, 1998). The relevance of this concept for the problem of sustainable economic development has been recognized for at least fifteen years (Common and Perrings, 1992). Indeed, Levin et al. (1998) claimed that resilience is the preferred way to think about sustainability in social as well as natural systems, and a research network – the Resilience Alliance – has subsequently developed around the idea.
Assessments must provide conditional predictions of the consequences of specific policy options, at well-defined spatial and temporal scales.
In recognition of our inability to halt damaging ...ecosystem change (
1
–
4
), the United Nations Environment Programme (UNEP) was asked in December 2010 to convene a meeting “to determine modalities and institutional arrangements” of a new assessment body, akin to the Intergovernmental Panel on Climate Change (IPCC), to track causes and consequences of anthropogenic ecosystem change (
5
). The “blueprint” for this body, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), lies in recommendations of an intergovernmental conference held in the Republic of Korea in June 2010: the Busan outcome (
6
). But it is a blueprint for governance rather than science. Using the experience from past assessments of global biodiversity and ecosystem services change (
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,
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,
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) and from the IPCC (
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), we ask what the policy-oriented charges in the Busan outcome imply for the science of the assessment process.
In the past two decades, avian influenzas have posed an increasing international threat to human and livestock health. In particular, highly pathogenic avian influenza H5N1 has spread across Asia, ...Africa, and Europe, leading to the deaths of millions of poultry and hundreds of people. The two main means of international spread are through migratory birds and the live poultry trade. We focus on the role played by the live poultry trade in the spread of H5N1 across three regions widely infected by the disease, which also correspond to three major trade blocs: the European Union (EU), the Economic Community of West African States (ECOWAS), and the Association of Southeast Asian Nations (ASEAN). Across all three regions, we found per-capita GDP (a proxy for modernization, general biosecurity, and value-at-risk) to be risk reducing. A more specific biosecurity measure-general surveillance-was also found to be mitigating at the all-regions level. However, there were important inter-regional differences. For the EU and ASEAN, intra-bloc live poultry imports were risk reducing while extra-bloc imports were risk increasing; for ECOWAS the reverse was true. This is likely due to the fact that while the EU and ASEAN have long-standing biosecurity standards and stringent enforcement (pursuant to the World Trade Organization's Agreement on the Application of Sanitary and Phytosanitary Measures), ECOWAS suffered from a lack of uniform standards and lax enforcement.
The Millennium Ecosystem Assessment identified habitat loss due to the extensive growth of agriculture as the primary driver of biodiversity loss. One implication of this is that agricultural ...intensification has the potential to reduce threats to wild species. In this paper we consider the evidence for differences in the threat to biodiversity posed by the intensive and extensive growth of agriculture in Sub-Saharan Africa. Using data on numbers of endemic species weighted by overall threat status, we analyze the impact of agricultural productivity growth and agricultural land conversion in 27 countries on threats to mammal, bird and plant species over two time scales: one covering the period since agricultural and environmental records began, the other covering the last decade. We find that the extensive growth of agriculture is associated with increasing threats to biodiversity at all time scales. While intensification is associated with a significant reduction in the threat to all species on long time scales, however, we find that it has no significant effect on shorter time scales.
Three interrelated world trends may be exacerbating emerging zoonotic risks: income growth, urbanization, and globalization. Income growth is associated with rising animal protein consumption in ...developing countries, which increases the conversion of wild lands to livestock production, and hence the probability of zoonotic emergence. Urbanization implies the greater concentration and connectedness of people, which increases the speed at which new infections are spread. Globalization—the closer integration of the world economy—has facilitated pathogen spread among countries through the growth of trade and travel. Highrisk areas for the emergence and spread of infectious disease are where these three trends intersect with predisposing socioecological conditions including the presence of wild disease reservoirs, agricultural practices that increase contact between wildlife and livestock, and cultural practices that increase contact between humans, wildlife, and livestock. Such an intersection occurs in China, which has been a "cradle" of zoonoses from the Black Death to avian influenza and SARS. Disease management in China is thus critical to the mitigation of global zoonotic risks.
Land cover change in watersheds affects the supply of a number of ecosystem services, including water supply, the production of timber and nontimber forest products, the provision of habitat for ...forest species, and climate regulation through carbon sequestration. The Panama Canal watershed is currently being reforested to protect the dry-season flows needed for Canal operations. Whether reforestation of the watershed is desirable depends on its impacts on all services. We develop a spatially explicit model to evaluate the implications of reforestation both for water flows and for other services. We find that reforestation does not necessarily increase water supply, but does increase carbon sequestration and timber production.
Exotic effects of capital accumulation Perrings, Charles
Proceedings of the National Academy of Sciences - PNAS,
07/2010, Letnik:
107, Številka:
27
Journal Article
The Millennium Ecosystem Assessment (MA) introduced a new framework for analyzing social-ecological systems that has had wide influence in the policy and scientific communities. Studies after the MA ...are taking up new challenges in the basic science needed to assess, project, and manage flows of ecosystem services and effects on human well-being. Yet, our ability to draw general conclusions remains limited by focus on discipline-bound sectors of the full social-ecological system. At the same time, some polices and practices intended to improve ecosystem services and human well-being are based on untested assumptions and sparse information. The people who are affected and those who provide resources are increasingly asking for evidence that interventions improve ecosystem services and human well-being. New research is needed that considers the full ensemble of processes and feedbacks, for a range of biophysical and social systems, to better understand and manage the dynamics of the relationship between humans and the ecosystems on which they rely. Such research will expand the capacity to address fundamental questions about complex social-ecological systems while evaluating assumptions of policies and practices intended to advance human well-being through improved ecosystem services.
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