Radiocarbon chronology of Iron Age Jerusalem reveals calibration offsets and architectural developments.

Reconstructing the absolute chronology of Jerusalem during the time it served as the Judahite Kingdom's capital is challenging due to its dense, still inhabited urban nature and the plateau shape of the radiocarbon calibration curve during part of this period. We present 103 radiocarbon dates from reliable archaeological contexts in five excavation areas of Iron Age Jerusalem, which tie between archaeology and biblical history. We exploit Jerusalem's rich past, including textual evidence and vast archaeological remains, to overcome difficult problems in radiocarbon dating, including establishing a detailed chronology within the long-calibrated ranges of the Hallstatt Plateau and recognizing short-lived regional offsets in atmospheric 14C concentrations. The key to resolving these problems is to apply stringent field methodologies using microarchaeological methods, leading to densely radiocarbon-dated stratigraphic sequences. Using these sequences, we identify regional offsets in atmospheric 14C concentrations c. 720 BC, and in the historically secure stratigraphic horizon of the Babylonian destruction in 586 BC. The latter is verified by 100 single-ring measurements between 624 to 572 BC. This application of intense 14C dating sheds light on the reconstruction of Jerusalem in the Iron Age. It provides evidence for settlement in the 12th to 10th centuries BC and that westward expansion had already begun by the 9th century BC, with extensive architectural projects undertaken throughout the city in this period. This was followed by significant damage and rejuvenation of the city subsequent to the mid-eight century BC earthquake, after which the city was heavily fortified and continued to flourish until the Babylonian destruction.

Hurricanes pose a substantial risk to New England forest carbon stocks.

Nature-based climate solutions (NCS) are championed as a primary tool to mitigate climate change, especially in forested regions capable of storing and sequestering vast amounts of carbon. New England is one of the most heavily forested regions in the United States (>75% forested by land area), and forest carbon is a significant component of climate mitigation policies. Large infrequent disturbances, such as hurricanes, are a major source of uncertainty and risk for policies relying on forest carbon for climate mitigation, especially as climate change is projected to alter the intensity and extent of hurricanes. To date, most research into disturbance impacts on forest carbon stocks has focused on fire. Here, we show that a single hurricane in the region can down between 121 and 250 MMTCO2e or 4.6%-9.4% of the total aboveground forest carbon, much greater than the carbon sequestered annually by New England's forests (16 MMTCO2e year-1). However, emissions from hurricanes are not instantaneous; it takes approximately 19 years for downed carbon to become a net emission and 100 years for 90% of the downed carbon to be emitted. Reconstructing hurricanes with the HURRECON and EXPOS models across a range of historical and projected wind speeds, we find that an 8% and 16% increase in hurricane wind speeds leads to a 10.7- and 24.8-fold increase in the extent of high-severity damaged areas (widespread tree mortality). Increased wind speed also leads to unprecedented geographical shifts in damage, both inland and northward, into heavily forested regions traditionally less affected by hurricanes. Given that a single hurricane can emit the equivalent of 10+ years of carbon sequestered by forests in New England, the status of these forests as a durable carbon sink is uncertain. Understanding the risks to forest carbon stocks from disturbances is necessary for decision-makers relying on forests as a NCS.

All tidal wetlands are blue carbon ecosystems.

Managing coastal wetlands is one of the most promising activities to reduce atmospheric greenhouse gases, and it also contributes to meeting the United Nations Sustainable Development Goals. One of the options is through blue carbon projects, in which mangroves, saltmarshes, and seagrass are managed to increase carbon sequestration and reduce greenhouse gas emissions. However, other tidal wetlands align with the characteristics of blue carbon. These wetlands are called tidal freshwater wetlands in the United States, supratidal wetlands in Australia, transitional forests in Southeast Asia, and estuarine forests in South Africa. They have similar or larger potential for atmospheric carbon sequestration and emission reductions than the currently considered blue carbon ecosystems and have been highly exploited. In the present article, we suggest that all wetlands directly or indirectly influenced by tides should be considered blue carbon. Their protection and restoration through carbon offsets could reduce emissions while providing multiple cobenefits, including biodiversity.

Flexibility trade-offs in conservation offsets.

Conservation offsets promise cost-effective conservation of biodiversity, especially under economic and environmental change, because they represent a more flexible approach to biodiversity conservation, allowing for the economic development of ecologically valuable land provided that this development is offset by restoration of previously developed areas. The level of flexibility is determined by the trading rules. Lax rules allow for more flexibility, which promises cost savings, but will likely lead to unintended loss of biodiversity. I analyzed the trade-off between economic costs and ecological benefits (biodiversity conservation) in biodiversity offsetting with an ecological-economic model that considered the three main types of offset flexibility: spatial, temporal, and ecosystem type. I sought to examine the influence of ecological and economic conditions on offset flexibility trade-offs. Large variation in the conservation costs and small costs of habitat restoration strongly increased trading activity and reduced the ecological benefit. The ecological benefit was most sensitive to spatial flexibility when a short range of ecological interaction was considered. At a large interaction range, spatial flexibility delivered large cost savings without overly reducing the ecological benefit. Risks and time lags associated with habitat restoration favored an offsetting scheme in which credits are awarded with the initiation of restoration projects rather than their successful completion-given appropriate offsetting multipliers were chosen. Altogether, under scarce resources, the level of flexibility in an offsetting scheme should be chosen by carefully balancing ecological benefits and economic costs.

Compromisos de flexibilidad en las compensaciones por conservación Resumen Las compensaciones por conservación prometen conservar la biodiversidad de forma rentable, especialmente de frente al cambio ambiental y económico. Ya que representan una estrategia más flexible para la conservación de la biodiversidad, esto permite el desarrollo económico de suelo con valor ecológico siempre y cuando este desarrollo esté compensado por la restauración de áreas con desarrollo previo. El nivel de flexibilidad está determinado por las reglas de intercambio. Las reglas laxas permiten una mayor flexibilidad, que promete ahorros, pero probablemente derive en la pérdida no intencionada de la biodiversidad. Analicé los compromisos entre los costos económicos y los beneficios ecológicos (conservación de la biodiversidad) en las compensaciones por biodiversidad con un modelo ecológico-económico que consideraba los tres tipos principales de flexibilidad: espacial, temporal y por tipo de ecosistema. Traté de examinar la influencia de las condiciones ecológicas y económicas sobre los compromisos de flexibilidad en las compensaciones. Una gran variación en los costos de conservación y los pequeños costos de la restauración del hábitat incrementaron fuertemente la actividad de intercambio y redujeron el beneficio ecológico. El beneficio ecológico fue más sensible a la flexibilidad espacial cuando consideré un corto alcance de la interacción ecológica. Con un alcance extenso, la flexibilidad espacial ofreció grandes ahorros son reducir por mucho el beneficio ecológico. Los riesgos y retrasos temporales asociados con la restauración del hábitat favorecieron un esquema de compensaciones en el que los créditos se otorgan al inicio del proyecto de restauración en lugar de con la conclusión exitosa del mismo-siempre y cuando se hayan elegido multiplicadores de compensación adecuados. En conjunto, si se tienen pocos recursos, el nivel de flexibilidad en un esquema de compensaciones debería elegirse con un balance cuidadoso entre los beneficios ecológicos y los costos económicos.

Air-sea carbon dioxide equilibrium: Will it be possible to use seaweeds for carbon removal offsets?

To limit global warming below 2°C by 2100, we must drastically reduce greenhouse gas emissions and additionally remove ~100-900 Gt CO2 from the atmosphere (carbon dioxide removal, CDR) to compensate for unavoidable emissions. Seaweeds (marine macroalgae) naturally grow in coastal regions worldwide where they are crucial for primary production and carbon cycling. They are being considered as a biological method for CDR and for use in carbon trading schemes as offsets. To use seaweeds in carbon trading schemes requires verification that seaweed photosynthesis that fixes CO2 into organic carbon results in CDR, along with the safe and secure storage of the carbon removed from the atmosphere for more than 100 years (sequestration). There is much ongoing research into the magnitude of seaweed carbon storage pools (e.g., as living biomass and as particulate and dissolved organic carbon in sediments and the deep ocean), but these pools do not equate to CDR unless the amount of CO2 removed from the atmosphere as a result of seaweed primary production can be quantified and verified. The draw-down of atmospheric CO2 into seawater is via air-sea CO2 equilibrium, which operates on time scales of weeks to years depending upon the ecosystem considered. Here, we explain why quantifying air-sea CO2 equilibrium and linking this process to seaweed carbon storage pools is the critical step needed to verify CDR by discrete seaweed beds and nearshore and open ocean aquaculture systems prior to their use in carbon trading.

Evaluating the impact of biodiversity offsetting on native vegetation.

Biodiversity offsetting is a globally influential policy mechanism for reconciling trade-offs between development and biodiversity loss. However, there is little robust evidence of its effectiveness. We evaluated the outcomes of a jurisdictional offsetting policy (Victoria, Australia). Offsets under Victoria's Native Vegetation Framework (2002-2013) aimed to prevent loss and degradation of remnant vegetation, and generate gains in vegetation extent and quality. We categorised offsets into those with near-complete baseline woody vegetation cover ("avoided loss", 2702 ha) and with incomplete cover ("regeneration", 501 ha), and evaluated impacts on woody vegetation extent from 2008 to 2018. We used two approaches to estimate the counterfactual. First, we used statistical matching on biophysical covariates: a common approach in conservation impact evaluation, but which risks ignoring potentially important psychosocial confounders. Second, we compared changes in offsets with changes in sites that were not offsets for the study duration but were later enrolled as offsets, to partially account for self-selection bias (where landholders enrolling land may have shared characteristics affecting how they manage land). Matching on biophysical covariates, we estimated that regeneration offsets increased woody vegetation extent by 1.9%-3.6%/year more than non-offset sites (138-180 ha from 2008 to 2018) but this effect weakened with the second approach (0.3%-1.9%/year more than non-offset sites; 19-97 ha from 2008 to 2018) and disappeared when a single outlier land parcel was removed. Neither approach detected any impact of avoided loss offsets. We cannot conclusively demonstrate whether the policy goal of 'net gain' (NG) was achieved because of data limitations. However, given our evidence that the majority of increases in woody vegetation extent were not additional (would have happened without the scheme), a NG outcome seems unlikely. The results highlight the importance of considering self-selection bias in the design and evaluation of regulatory biodiversity offsetting policy, and the challenges of conducting robust impact evaluations of jurisdictional biodiversity offsetting policies.

Systematic over-crediting in California's forest carbon offsets program.

Carbon offsets are widely used by individuals, corporations, and governments to mitigate their greenhouse gas emissions on the assumption that offsets reflect equivalent climate benefits achieved elsewhere. These climate-equivalence claims depend on offsets providing real and additional climate benefits beyond what would have happened, counterfactually, without the offsets project. Here, we evaluate the design of California's prominent forest carbon offsets program and demonstrate that its climate-equivalence claims fall far short on the basis of directly observable evidence. By design, California's program awards large volumes of offset credits to forest projects with carbon stocks that exceed regional averages. This paradigm allows for adverse selection, which could occur if project developers preferentially select forests that are ecologically distinct from unrepresentative regional averages. By digitizing and analyzing comprehensive offset project records alongside detailed forest inventory data, we provide direct evidence that comparing projects against coarse regional carbon averages has led to systematic over-crediting of 30.0 million tCO2 e (90% CI: 20.5-38.6 million tCO2 e) or 29.4% of the credits we analyzed (90% CI: 20.1%-37.8%). These excess credits are worth an estimated $410 million (90% CI: $280-$528 million) at recent market prices. Rather than improve forest management to store additional carbon, California's forest offsets program creates incentives to generate offset credits that do not reflect real climate benefits.

Using remote sensing to quantify the additional climate benefits of California forest carbon offset projects.

Nature-based climate solutions are a vital component of many climate mitigation strategies, including California's, which aims to achieve carbon neutrality by 2045. Most carbon offsets in California's cap-and-trade program come from improved forest management (IFM) projects. Since 2012, various landowners have set up IFM projects following the California Air Resources Board's IFM protocol. As many of these projects approach their 10th year, we now have the opportunity to assess their effectiveness, identify best practices, and suggest improvements toward future protocol revisions. In this study, we used remote sensing-based datasets to evaluate the carbon trends and harvest histories of 37 IFM projects in California. Despite some current limitations and biases, these datasets can be used to quantify carbon accumulation and harvest rates in offset project lands relative to nearby similar "control" lands before and after the projects began. Five lines of evidence suggest that the carbon accumulated in offset projects to date has generally not been additional to what might have otherwise occurred: (1) most forests in northwestern California have been accumulating carbon since at least the mid-1980s and continue to accumulate carbon, whether enrolled in offset projects or not; (2) harvest rates were high in large timber company project lands before IFM initiation, suggesting they are earning carbon credits for forests in recovery; (3) projects are often located on lands with higher densities of low-timber-value species; (4) carbon accumulation rates have not yet increased on lands that enroll as offset projects, relative to their pre-enrollment levels; and (5) harvest rates have not decreased on most project lands since offset project initiation. These patterns suggest that the current protocol should be improved to robustly measure and reward additionality. In general, our framework of geospatial analyses offers an important and independent means to evaluate the effectiveness of the carbon offsets program, especially as these data products continue improving and as offsets receive attention as a climate mitigation strategy.

Ecological and economic implications of alternative metrics in biodiversity offset markets.

Policy tools are needed that allow reconciliation of human development pressures with conservation priorities. Biodiversity offsetting can be used to compensate for ecological losses caused by development activities. Landowners can choose to undertake conservation actions, including habitat restoration, to generate biodiversity offsets. Consideration of the incentives facing landowners as potential biodiversity offset providers and developers as potential buyers of credits is critical when considering the ecological and economic landscape-scale outcomes of alternative offset metrics. There is an expectation that landowners will always seek to conserve the least profitable land parcels, and, in turn, this determines the spatial location of biodiversity offset credits. We developed an ecological-economic model to compare the ecological and economic outcomes of offsetting for a habitat-based metric and a species-based metric. We were interested in whether these metrics would adequately capture the indirect benefits of offsetting on species not considered under a no-net-loss policy. We simulated a biodiversity offset market for a case study landscape, linking species distribution modeling and an economic model of landowner choice based on economic returns of the alternative land management options (restore, develop, or maintain existing land use). Neither the habitat nor species metric adequately captured the indirect benefits of offsetting on related habitats or species. The underlying species distributions, layered with the agricultural and development rental values of parcels, resulted in very different landscape outcomes depending on the metric chosen. If policy makers are aiming for the metric to act as an indicator to mitigate impacts on a range of closely related habitats and species, then a simple no-net-loss target is not adequate. Furthermore, to achieve the most ecologically beneficial design of offsets policy, an understanding of the economic decision-making processes of the landowners is needed.

Se necesitan herramientas políticas que permitan la reconciliación entre las presiones del desarrollo humano y las prioridades de conservación. La compensación de biodiversidad puede usarse para reponer las pérdidas ecológicas causadas por las actividades de desarrollo. Los terratenientes pueden elegir realizar acciones de conservación, incluyendo la restauración del hábitat, para generar dichas compensaciones. Es importante considerar los incentivos para los terratenientes como proveedores potenciales de compensaciones de biodiversidad y para los desarrolladores como compradores potenciales de créditos cuando se contemplan los resultados ecológicos y económicos a escala de paisaje de estas medidas alternativas de compensación. Existe la expectativa de que los terratenientes siempre buscarán conservar los lotes menos rentables y, por lo tanto, esto determina la ubicación espacial de los créditos por compensación de biodiversidad. Desarrollamos un modelo para comparar los resultados ecológicos y económicos de la compensación en una medida basada en el hábitat y una basada en la especie. Nos interesaba saber si estas medidas indicarían adecuadamente los beneficios indirectos de la compensación para las especies no consideradas bajo una política de pérdida neta cero. Simulamos un mercado voluntario de biodiversidad para un estudio de casode un paisaje, el cual vinculó el modelado de la distribución de especies con el modelo económico de las elecciones de los terratenientes basadas en las ganancias económicas de las opciones alternativas de manejo de suelo (restaurar, desarrollar o mantener el uso de suelo existente). Ninguna de las dos medidas indicó adecuadamente los beneficios indirectos de la compensación para las especies o hábitats relacionados. La distribución subyacente de especies, en conjunto con los valores de renta agrícolas y de desarrollo de los lotes, derivó en resultados muy diferentes de paisaje según la medida seleccionada. Cuando los formuladores de políticas buscan que la medida actúe como un indicador para mitigar impactos en una gama de especies y hábitats relacionados cercanamente, no es adecuado un objetivo simple de pérdida neta cero. Además, para lograr el diseño con el mayor beneficio ecológico, se requiere comprender los procesos de decisión de los terratenientes.

Guidelines for selecting an appropriate currency in biodiversity offset transactions.

When designing biodiversity offset transactions, selecting the appropriate currency for measuring losses and gains to biodiversity is crucial. Poorly designed currencies reduce the likelihood that the proposed offset will sufficiently compensate for the development impact on the affected biota. We present a framework for identifying appropriate offset currencies for terrestrial biodiversity features, either vegetation communities or particular species. The guidelines were developed based on a review of issues and solutions presented in the existing literature, including government policies and guidance. We assert that while benchmark-based condition scores provide a suitable offset transaction currency for vegetation communities, this approach is also commonly applied to individual species based on the often-unproven assumption that vegetation quality is a proxy for the value of a site to that species. We argue that species are better served by species-specific currencies based on either species abundance, or the suitability and amount of the habitat available. For species where it is practical and meaningful to measure the abundance on site, an abundance-based currency using either directly observable or proxy indicators is the most representative measure of the net impact on the species. In other instances, such as when species are difficult to locate, or not reliably present on site, a currency based on the quality and amount of habitat is preferable. The habitat-quality component should be measured relative to its value for the species, with the most important attributes weighted accordingly. Ensuring the currency used in biodiversity offset transactions is practical to measure, and relevant to the species or vegetation community is an important step in minimising the net biodiversity losses from unavoidable impacts.

'Old wine in a new bottle': conceptualization of biodiversity offsets among environmental practitioners in Uganda.

Biodiversity offsets are increasingly adopted to mitigate the negative impacts of development activities on biodiversity. However, in practice, there are inconsistencies in how biodiversity offsets are understood and implemented. Based on interviews with environmental practitioners, the study sought to explore the conceptual understanding of biodiversity offsets among personnel involved in the design and implementation of offset schemes in Uganda. The study employed a 'technical use analysis' to seek personal interpretation and operationalization of the concept of biodiversity offsets. The results revealed that the concept tends to be simplified and adjusted to individual, project, and country contexts. The respondents had varied perceptions of biodiversity offsets in practice as compared to the theoretical concept. Biodiversity offsets were classified under five terms: trade-offs, payments, substitutes, compensations, and mitigation measures. The terms were derived from perceived inability of the measure to attain no net loss, and similarities of biodiversity components and services across impact and offset sites. Biodiversity offsets were thus considered no different from ordinary environmental conservation measures, contributing nothing unique to the conservation agenda. The study concludes that widespread implementation of biodiversity offsets under prevailing perceptions will escalate biodiversity loss. The study recommends emphasis on attaining no net loss through implementing outcome-based offsets as opposed to purpose-based offsets, that require delivering of 'no net loss' gains prior to projects being considered biodiversity offsets.

Rational Design of Semiconductor Heterojunctions for Photocatalysis.

Electronic structure calculations provide a useful complement to experimental characterization tools in the atomic-scale design of semiconductor heterojunctions for photocatalysis. The band alignment of the heterojunction is of fundamental importance to achieve an efficient charge carrier separation, so as to reduce electron/hole recombination and improve photoactivity. The accurate prediction of the offsets of valence and conduction bands in the constituent units is thus of key importance but poses several methodological and practical problems. In this Minireview we address some of these problems by considering selected examples of binary and ternary semiconductor heterojunctions and how these are determined at the level of density functional theory (DFT). The atomically precise description of the interface, the consequent charge polarization, the role of quantum confinement, the possibility to use facet engineering to determine a specific band alignment, are among the effects discussed, with particular attention to pros and cons of each one of these aspects. This analysis shows the increasingly important role of accurate electronic structure calculations to drive the design and the preparation of new interfaces with desired properties.

Does Cost-Effectiveness Analysis Overvalue Potential Cures? Exploring Alternative Methods for Applying a "Shared Savings" Approach to Cost Offsets.

OBJECTIVES: To evaluate alternative methods to calculate and/or attribute economic surplus in the cost-effectiveness analysis of single or short-term therapies. METHODS: We performed a systematic literature review of articles describing alternative methods for cost-effectiveness analysis of potentially curative therapies whose assessment using traditional methods may suggest unaffordable valuations owing to the magnitude of estimated long-term quality-adjusted life-year (QALY) gains or cost offsets. Through internal deliberation and discussion with staff at the Health Technology Assessment bodies in England and Canada, we developed the following 3 alternative methods for further evaluation: (1) capping annual costs in the comparator arm at $150 000 per year; (2) "sharing" the economic surplus with the health sector by apportioning only 50% of cost offsets or 50% of cost offsets and QALY gains to the value of the therapy; and (3) crediting the therapy with only 12 years of the average annual cost offsets or cost offsets and QALY gains over the lifetime horizon. The impact of each alternative method was evaluated by applying it in an economic model of 3 hypothetical condition-treatment scenarios meant to reflect a diversity of chronicity and background healthcare costs. RESULTS: The alternative with greatest impact on threshold price for the fatal pediatric condition spinal muscular atrophy type 1 was the 12-year cutoff scenario. For a hypothetical one-time treatment for hemophilia A, capping cost offsets at $150 000 per year had the greatest impact. For chimeric antigen receptor T-cell treatment of non-Hodgkin's lymphoma, capping cost offsets or using 12-year threshold had little impact, whereas 50% sharing of surplus including QALY gains and cost offsets greatly reduced threshold pricing. CONCLUSIONS: Health Technology Assessment bodies and policy makers will wrestle with how to evaluate single or short-term potentially curative therapies and establish pricing and payment mechanisms to ensure sustainability. Scenario analyses using alternative methods for calculating and apportioning economic surplus can provide starkly different assessment results. These methods may stimulate important societal dialogue on fair pricing for these novel treatments.

Synergies and trade-offs among integrated conservation approaches in Mexico.

Integrated conservation approaches (ICAs) are employed by governments, communities, and nongovernmental organizations worldwide seeking to achieve outcomes with dual benefits for biodiversity conservation and poverty alleviation. Although ICAs are frequently implemented concurrently, interactions among ICAs and the synergies or trade-offs that result are rarely considered during program design, implementation, and evaluation. In support of more deliberate and effective use of ICAs, we examined interactions among four well-known strategies: biosphere reserves (BRs), voluntary protected areas (VPAs), payments for ecosystem services (PES), and community forest management (CFM). Through a comparative case study, we analyzed interactions among spatially or temporally clustered ICAs implemented on communally held and managed lands in three ecologically and socioeconomically distinct regions of Mexico. Our research methods combined policy analysis with data gathered through participant observation and semistructured interviews (n = 78) and focus groups (n = 5) with government officials, implementers, and participants involved in ICAs in 28 communities. Despite the significant differences among the regions in which they were implemented, we found that key actors at each level of involvement generally perceived interactions among ICAs as synergistic. The PES programs were perceived to strengthen protected areas by reducing forest cover loss in and around BRs, fostering proconservation attitudes, and incentivizing the establishment of VPAs. Communities that invested PES income in CFM were motivated to conserve forests beyond the duration of PES programs, and CFM in buffer zones was perceived to strengthen BRs by maintaining forest cover and generating income for communities. We also identified key social and environmental factors that can influence these interaction effects among ICAs. Based on these findings, we recommend further study of ICA interactions and intentionally complementary policy design to maximize positive environmental and social outcomes.

Las estrategias de conservación integrada (ECI) son empleadas en todo el mundo por los gobiernos, comunidades y organizaciones no gubernamentales que buscan alcanzar resultados con beneficios tanto para la conservación como para la mitigación de la pobreza. A pesar de que múltiples ECI suelen implementarse simultáneamente, es raro que se tomen en cuenta las posibles interacciones positivas (sinergías) o negativas (trade-offs) durante el diseño, la implementación y la evaluación de estos programas. En búsqueda de un uso más deliberado y efectivo de las ECI, examinamos las interacciones entre cuatro estrategias conocidas: reservas de la biósfera (RB), áreas protegidas voluntarias (APV), pagos por servicios ambientales (PSA) y el manejo comunitario de los bosques (MCB). Mediante un estudio de caso comparativo analizamos las interacciones entre las ECI agrupadas espacial o temporalmente implementadas en tierras con administración y propiedad comunal en tres regiones con diferencias ecológicas y socioeconómicas en México. Nuestros métodos de investigación combinaron el análisis de políticas con datos recopilados mediante la observación participativa, entrevistas semiestructuradas (n = 78) y grupos focales (n = 5) con funcionarios del gobierno, implementadores y participantes involucrados en las ECI de 28 comunidades. A pesar de las diferencias significativas entre las regiones en las que se implementaron estas ECI, descubrimos que los actores clave en cada nivel de participación percibieron de manera generalizada las interacciones entre las ECI como sinérgicas. Los programas de PSA fueron percibidos como algo que fortalece a las áreas protegidas mediante la reducción de la pérdida de la cobertura forestal dentro y fuera de las RB, el fomento de las actitudes a favor de la conservación y el estímulo al establecimiento de las APV. Las comunidades que invirtieron los ingresos por PSA en el MCB expresaron su motivación para conservar los bosques más allá de la duración de los programas de PSA y el MCB en zonas de amortiguamiento fue percibido como un factor de fortalecimiento de las RB mediante el mantenimiento de la cobertura forestal y la generación de ingresos para las comunidades. También identificamos los factores sociales y ambientales importantes que pueden influir sobre estos efectos de interacción entre las ECI. Con base en estos hallazgos, recomendamos un estudio más profundo de las interacciones entre las ECI y un diseño de políticas intencionalmente complementario para maximizar los resultados sociales y ambientales positivos.

Quantifying the impact of vegetation-based metrics on species persistence when choosing offsets for habitat destruction.

Developers are often required by law to offset environmental impacts through targeted conservation actions. Most offset policies specify metrics for calculating offset requirements, usually by assessing vegetation condition. Despite widespread use, there is little evidence to support the effectiveness of vegetation-based metrics for ensuring biodiversity persistence. We compared long-term impacts of biodiversity offsetting based on area only; vegetation condition only; area × habitat suitability; and condition × habitat suitability in development and restoration simulations for the Hunter Region of New South Wales, Australia. We simulated development and subsequent offsetting through restoration within a virtual landscape, linking simulations to population viability models for 3 species. Habitat gains did not ensure species persistence. No net loss was achieved when performance of offsetting was assessed in terms of amount of habitat restored, but not when outcomes were assessed in terms of persistence. Maintenance of persistence occurred more often when impacts were avoided, giving further support to better enforce the avoidance stage of the mitigation hierarchy. When development affected areas of high habitat quality for species, persistence could not be guaranteed. Therefore, species must be more explicitly accounted for in offsets, rather than just vegetation or habitat alone. Declines due to a failure to account directly for species population dynamics and connectivity overshadowed the benefits delivered by producing large areas of high-quality habitat. Our modeling framework showed that the benefits delivered by offsets are species specific and that simple vegetation-based metrics can give misguided impressions on how well biodiversity offsets achieve no net loss.

Cuantificación del Impacto de las Medidas Basadas en la Vegetación sobre la Persistencia de las Especies cuando se Eligen las Compensaciones por la Destrucción del Hábitat Resumen Con frecuencia se requiere por ley que los desarrolladores compensen los impactos ambientales por medio de acciones de conservación. La mayoría de las políticas de compensación especifican medidas para calcular los requerimientos de cada compensación, generalmente mediante la evaluación de las condiciones de la vegetación. A pesar del uso extenso de estas medidas basadas en la vegetación, existe muy poca evidencia que respalde su efectividad para asegurar la persistencia de la biodiversidad. Comparamos los impactos a largo plazo de las compensaciones de biodiversidad basadas solamente en el área; solamente en la condición de la vegetación; la idoneidad del área x hábitat; y la idoneidad condición x hábitat en las simulaciones de desarrollo y restauración para la Región Hunter de Nueva Gales del Sur, Australia. Simulamos el desarrollo y las compensaciones subsecuentes mediante la restauración dentro de un paisaje virtual, conectando las simulaciones con los modelos de viabilidad poblacional para tres especies. Las ganancias del hábitat no aseguraron la persistencia de las especies. No hubo pérdida neta cuando el desempeño de las compensaciones se evaluó en relación con la persistencia. El mantenimiento de la persistencia ocurrió más seguido cuando se evitaron los impactos, lo que proporciona un mayor respaldo para mejorar la aplicación de la fase de prevención de la jerarquía de mitigación. Cuando el desarrollo afectó a las áreas con una alta calidad de hábitat para las especies, no se pudo garantizar la persistencia. Por lo tanto, las especies deben considerarse más explícitamente en las compensaciones, en lugar de sólo considerar a la vegetación o al hábitat. Las declinaciones causadas por la falta de consideración directa de las dinámicas poblacionales de las especies y de la conectividad opacaron los beneficios producidos por las grandes áreas de hábitat de alta calidad. Nuestro marco de trabajo para el modelado demostró que los beneficios producidos por las compensaciones son específicos para cada especie y que las medidas simples basadas en la vegetación pueden brindar impresiones mal informadas sobre qué tanto influyen las compensaciones de biodiversidad en la no pérdida neta.

Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates.

Considerable work has gone into developing high-precision radiocarbon (14C) chronologies for the southern Levant region during the Late Bronze to Iron Age/early Biblical periods (∼1200-600 BC), but there has been little consideration whether the current standard Northern Hemisphere 14C calibration curve (IntCal13) is appropriate for this region. We measured 14C ages of calendar-dated tree rings from AD 1610 to 1940 from southern Jordan to investigate contemporary 14C levels and to compare these with IntCal13. Our data reveal an average offset of ∼19 14C years, but, more interestingly, this offset seems to vary in importance through time. While relatively small, such an offset has substantial relevance to high-resolution 14C chronologies for the southern Levant, both archaeological and paleoenvironmental. For example, reconsidering two published studies, we find differences, on average, of 60% between the 95.4% probability ranges determined from IntCal13 versus those approximately allowing for the observed offset pattern. Such differences affect, and even potentially undermine, several current archaeological and historical positions and controversies.

The Celestial Frame and the Weighting of the Celestial Pole Offsets in the Computation of VLBI-Based Corrections for the Main Lunisolar Nutation Terms.

Very long baseline interferometry (VLBI) is the only technique in space geodesy that can determine directly the celestial pole offsets (CPO). In this paper, we make use of the CPO derived from global VLBI solutions to estimate empirical corrections to the main lunisolar nutation terms included in the IAU 2006/2000A precession-nutation model. In particular, we pay attention to two factors that affect the estimation of such corrections: the celestial reference frame used in the production of the global VLBI solutions and the stochastic model employed in the least-squares adjustment of the corrections. In both cases, we have found that the choice of these aspects has an effect of a few µas in the estimated corrections.

Pooling biodiversity offsets to improve habitat connectivity and species conservation.

Land developers can apply biodiversity offsetting in different ways, from a project-by-project approach to a pooled and proactive approach, this latter appearing to provide greater advantages both in terms of implementation and of the No Net Loss objective. Incorporating landscape connectivity into the mitigation hierarchy is commonly recommended, but the benefits of pooling and anticipating offsets have never really been demonstrated from modeling approaches. Here, we compare connectivity gains from two different offsetting scenarios, when interconnections at offset sites are taken and not taken into account. Assuming that gains can be increased by optimizing the location of offsets, we identified sites where biodiversity offsetting generates the greatest ecological gains in habitat connectivity. The method was applied to a study case in the suburbs of Lyon (Southern France) using several representative species and the landscape functional connectivity model Graphab. Pooling biodiversity offsets led to additional gains in overall habitat connectivity of +103% on average, which we show can be further improved (+8%) by using a patch addition process available in Graphab to plan spatially and ecologically coherent offsetting areas. Pooling and anticipating biodiversity offsets in this way can help preserve the biodiversity and the functionality of natural environments at the territorial scale.

Exploring the practical implementation of marine biodiversity offsetting in Australia.

Biodiversity offsetting with associated aims of no net loss of biodiversity (NNL) is an approach used to align economic development with conservation. Biodiversity offsetting may be more challenging in marine environments, with recent evidence suggesting that the current application of the approach in Australian marine environments rarely follows 'best practice' and is unlikely to be meeting stated policy aims. To understand how and why this deviation from best practice is taking place in marine systems, we analysed current practice in Australia through in-depth semi-structured interviews with 31 participants with professional experience in the development and implementation of associated policy. Thematic analysis of results indicated that, despite commitment to best practice in principle, practitioners recognised that operationalisation of marine biodiversity offsetting was inconsistent and unlikely to be meeting stated goals such as NNL. Participants described the central barrier to the adoption of best practice as the technical complexity of assessing and quantifying biodiversity losses and gains, and uncertainty in restoration in marine contexts. With offsetting described as an integral part of development consent for marine economic development, both these barriers and their navigation presents threats to users setting off a chain of accepted activity leading away from best practice. These threats were perceived to arise from low governmental capacity or prioritisation for environmental management, institutional needs for a social licence to operate, and overarching demands for economic growth. We conclude that marine biodiversity offsetting has come to be ambiguous in its practical definition, with a range of conflicting factors influencing its use and preventing the standardisation required to meet rigorous interpretations of best practice necessary to ensure biodiversity protection and NNL.

When is an Offset Not an Offset? A Framework of Necessary Conditions for Biodiversity Offsets.

Biodiversity offsets have become a widely accepted means of attempting to compensate for biodiversity loss from development, and are applied in planning and decision-making processes at many levels. Yet their use is contentious, and numerous problems with both the concept and the practice have been identified in the literature. Our starting point is the understanding that offsets are a kind of biodiversity compensation measure through which the goal of no net loss (or net gain) of biodiversity can be at least theoretically achieved. Based on a typology of compensation measures distinguishing between habitat protection, improvement (including restoration, habitat creation and improved management practices) and other compensation, we review the literature to develop a framework of conditions that must be met if habitat protection and improvement initiatives can be truly considered offsets and not merely a lesser form of compensation. It is important that such conceptual clarity is reflected in offset policy and guidance, if offsets are to be appropriately applied and to have any chance of fully compensating for biodiversity loss. Our framework can be used to support the review and ongoing development of biodiversity offset policy and guidance, with the aim of improving clarity, rigour and therefore the chances that good biodiversity outcomes can be achieved.