Peer-reviewed publications

Many human populations are dependent on marine ecosystems for a range of benefits but we understand little about where and to what degree people rely on these ecosystem services. We created a new conceptual model to map the degree of human dependence on marine ecosystems based on the magnitude of the benefit, susceptibility of people to a loss of that benefit, and the availability of alternatives. We focused on mapping nutritional, economic, and coastal protection dependence, but our model is repeatable, scalable, applicable to other ecosystems, and designed to incorporate additional services and data. Here we show that dependence was highest for Pacific and Indian Ocean island nations and several West African countries. More than 775 million people live in areas with relatively high dependence scores. By identifying where and how people are dependent on marine ecosystems, our framework can be used to design more effective large-scale management and policy interventions.

Increasing human populations around the global coastline have caused extensive loss, degradation and fragmentation of coastal ecosystems, threatening the delivery of important ecosystem services. As a result, alarming losses of mangrove, coral reef, seagrass, kelp forest and coastal marsh ecosystems have occurred. However, owing to the difficulty of mapping intertidal areas globally, the distribution and status of tidal flats–one of the most extensive coastal ecosystems–remain unknown. Here we present an analysis of over 700,000 satellite images that maps the global extent of and change in tidal flats over the course of 33 years (1984-2016). We find that tidal flats, defined as sand, rock or mud flats that undergo regular tidal inundation, occupy at least 127,921 km2(124,286-131,821 km2, 95% confidence interval). About 70% of the global extent of tidal flats is found in three continents (Asia (44% of total), North America (15.5% of total) and South America (11% of total)), with 49.2% being concentrated in just eight countries (Indonesia, China, Australia, the United States, Canada, India, Brazil and Myanmar). For regions with sufficient data to develop a consistent multi-decadal time series–which included East Asia, the Middle East and North America–we estimate that 16.02% (15.62-16.47%, 95% confidence interval) of tidal flats were lost between 1984 and 2016. Extensive degradation from coastal development, reduced sediment delivery from major rivers, sinking of riverine deltas, increased coastal erosion and sea-level rise signal a continuing negative trajectory for tidal flat ecosystems around the world. Our high-spatial-resolution dataset delivers global maps of tidal flats, which substantially advances our understanding of the distribution, trajectory and status of these poorly known coastal ecosystems.

The links between plantation expansion and deforestation in Borneo are debated. We used satellite imagery to map annual loss of old-growth forests, expansion of industrial plantations (oil palm and pulpwood), and their overlap in Borneo from 2001 to 2017. In 17 years, forest area declined by 14% (6.04 Mha), including 3.06 Mha of forest ultimately converted into industrial plantations. Plantations expanded by 170% (6.20 Mha: 88% oil palm; 12% pulpwood). Most forests converted to plantations were cleared and planted in the same year (92% 2.83 Mha). Annual forest loss generally increased before peaking in 2016 (0.61 Mha) and declining sharply in 2017 (0.25 Mha). After peaks in 2009 and 2012, plantation expansion and associated forest conversion have been declining in Indonesia and Malaysia. Annual plantation expansion is positively correlated with annual forest loss in both countries. The correlation vanishes when we consider plantation expansion versus forests that are cleared but not converted to plantations. The price of crude palm oil is positively correlated with plantation expansion in the following year in Indonesian (not Malaysian) Borneo. Low palm oil prices, wet conditions, and improved fire prevention all likely contributed to reduced 2017 deforestation. Oversight of company conduct requires transparent concession ownership.

Non-state and subnational climate actors have become central to global climate change governance. Quantitatively assessing climate mitigation undertaken by these entities is critical to understand the credibility of this trend. In this Perspective, we make recommendations regarding five main areas of research and methodological development related to evaluating non-state and subnational climate actions: defining clear boundaries and terminology; use of common methodologies to aggregate and assess non-state and subnational contributions; systematically dealing with issues of overlap; estimating the likelihood of implementation; and addressing data gaps.

Key messages

There are three approaches to private sector commitments on zero deforestation: individual company or group-level adoption of voluntary standards; sector-wide supply chain-based interventions; and mixed supply chain and territorial initiatives at jurisdictional level.

The main implementation challenges of these approaches are the limits of voluntary standards, traceability systems that are difficult to implement, selective actions that cannot deliver at scale, associated leakage effects, and persistence of segmented supply chains.

Approaches have evolved to deal with such challenges, however progress requires committed companies to increase implementation efforts, other supply chain actors to adhere to commitments, and governments to harness the potential of jurisdictional approaches.

This chapter provides a general description of benefits and consideration of economic valuation of those benefits that can be derived from coastal habitats that store and sequester carbon (C): seagrass meadows and wetlands, which include marshes and mangrove forests. It presents examples of important ecosystem services (ESs) and their valuation. Before assessing an economic value to these ESs at different spatial scales, it is critical to obtain accurate estimates of mangrove biomass and C stocks for mangrove ecotypes. During the 19th century, coastal wetlands often were considered a nuisance environment and perceived as competing against other human uses that serve immediate economic needs. Several attempts have been made to calculate economic values for these ESs globally, but economic valuation studies have estimated more credible results when focused on a smaller area where marginal values of some of these ESs can be calculated.

Since the 1990s, the Intergovernmental Panel on Climate Change (IPCC) has used global assessments of vulnerability to inform investment and action against the effects of climate change. Beyond the IPCC, others have undertaken global assessments to understand the vulnerability of coastal areas to climate change. Eight global vulnerability assessments are compared to understand similarities and differences in their results and the metrics used to construct a vulnerability index. Variations in objectives, conceptualizations of vulnerability, operationalization of the concepts, scope and depth of data drawn upon lead to contradictory rankings of priority areas for climate action between assessments. The increased complexity and scope of indicators make it difficult to untangle the root causes of such differences in rankings. It is also difficult to identify the degree to which climate change influences vulnerability rankings compared to other factors such as local environmental conditions and the capacity of populations to deal with environmental change. The way to undertake global assessments needs to be reshaped to better inform planning of international development along different objectives. Global level assessments need to be simplified and harmonized to better isolate the impact of climate change specific drivers. Decision-makers would make better use of such global assessments as scoping studies rather than expect comprehensive and robust priorities for investment. Such scoping studies can help target locations where supplementary, in-depth local analyses need to be conducted. At the local level, the possibility to collect context-specific information, particularly on adaptive capacity, allows the robust assessment of vulnerability.

Social conflicts related to biodiversity conservation and adaptation policy to climate change in coastal areas illustrate the need to reinforce understanding of the “matters of concern” as well as the “matters of fact”. In this paper, we argue that we must rethink adaptation from a new perspective, considering that humans together function as both ecological actors and social actors. Using international examples from the UNESCO world biosphere reserve network, we show that an ontological perspective may provide a simple and compact way to think about coupled infrastructure systems and systematic formalism, allowing for understanding of the relational matrix between actors, institutions and ecosystems. We contend that our formalism responds to three challenges. First, it encompasses the different regional contexts and policies that rely on the same ontology. Second, it provides a method to relate any local adaptation plan to the conservation paradigms that originate from the ecological modernization of policies. Third, it facilitates the discovery of drivers and processes involved in adaptation and management regime shifts by highlighting the way contextual factors configure, determine the structure of the action situation of the Institutional Analysis and Development framework (IAD) (Ostrom 2005), and how it operates.

Tourism may benefit conservation, but some wildlife viewing practices threaten the sustainability of both business and conservation initiatives. In north-west Namibia, conservation-oriented tourism provides tourists with an opportunity to encounter the critically-endangered black rhinoceros Diceros bicornis on foot. We used 123 tourist-rhinoceros encounters and employed a statistical modeling approach to: (1) identify the characteristics of human-rhinoceros encounters that caused rhinoceros disturbance and displacement; and (2) design rhinoceros-human encounter guidelines that improve sustainability. A model-averaging, information-theoretic approach identified tourist approach distance, viewing time and individual encounter exposure as the most significant predictors of rhinoceros disturbance level. A suite of rhinoceros viewing scenarios were modeled for acceptable disturbance risks, and adopted as a rhinoceros viewing policy. The policy reduced encounter displacements by 80% while maintaining a 95% positive feedback rating from guests. We demonstrate an evidence-based, policy-oriented management approach can help improve tourism's contribution towards the conservation of an endangered species.

Tourism may benefit conservation, but some wildlife viewing practices threaten the sustainability of both business and conservation initiatives. In north-west Namibia, conservation-oriented tourism provides tourists with an opportunity to encounter the critically-endangered black rhinoceros Diceros bicornis on foot. We used 123 tourist-rhinoceros encounters and employed a statistical modeling approach to: (1) identify the characteristics of human-rhinoceros encounters that caused rhinoceros disturbance and displacement; and (2) design rhinoceros-human encounter guidelines that improve sustainability. A model-averaging, information-theoretic approach identified tourist approach distance, viewing time and individual encounter exposure as the most significant predictors of rhinoceros disturbance level. A suite of rhinoceros viewing scenarios were modeled for acceptable disturbance risks, and adopted as a rhinoceros viewing policy. The policy reduced encounter displacements by 80% while maintaining a 95% positive feedback rating from guests. We demonstrate an evidence-based, policy-oriented management approach can help improve tourism's contribution towards the conservation of an endangered species.