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As various political initiatives have set goals to reach net-zero emissions bythe mid-21st century, forests will play an important role as a carbon sink for sequesteringunavoidable emissions. Forest management can take two approachesby either decreasing harvest and enlarging the forest carbon stock or increasingharvest to increase carbon uptake of the remaining forest stock and create harvestedwood products (HWPs). Currently, these two management options seemat odds with seemingly conflicting policy directives being written. We used theBEKLIFUH model to assess six management scenarios based on carbon offsetpotential taking into consideration forest carbon, HWPs and the material andenergetic substitution effects. The results show that while conservation leadsto a higher above-ground carbon pool, including HWPs, material and energeticsubstitution leads to more overall carbon offsets for management scenarios withmore timber harvesting. With compromise being possible by selectively conservingold growth forests with a high biodiversity value. In conclusion, if theforest sector decouples GHG reporting from forest management and includesall the secondary effects of timber harvest, this new approach can lead to adifferent cost–benefit analysis for the choice between harvest vs. conservation.This could result in a paradigm shift to a future where biodiversity and carbonneutrality can coexist.

This study explored people’s perceptions of climate change by conducting interviews and focus-group discussions with local residents of three ecological regions of Nepal, i.e., mountain, midhills, and lowland. Climatic measurements from meteorological stations of the regions were acquired for the period from 1988 to 2018. We compared the people’s perception with trends and variabilities of observed temperature and rainfall patterns. The results showed that, over the last three decades, temperature and precipitation trends and variability between regions varied, largely corroborating the local experiences. The temperature increased in mountain, midhills, and lowland by 0.061°, 0.063°, and 0.017°C yr−1, respectively. In contrast, rainfall decreased by −9.7, −3.6, and −0.04 mm yr−1 for the regions, respectively. Although the amount of rainfall decrease observed in the mountain was highest, its variability was found to be relatively low, and vice versa in lowland. Approximately 88% of interviewees perceived temperature rise, and 74% noticed rainfall decline. Local residents linked these changes with their livelihood activities, as exemplified by, for example, crop’s quality and quantity and birds’ migration. The results indicate that local understandings complement the scarce observational data and provide a reliable and additional foundation to determine changes in climatic variables. Moreover, the result infers that small changes in climate variables have noticeable implications on human behavior change. Therefore, besides active participation of local communities, integrating local understanding is crucial in developing climate change–related policies and strategies at local and national levels.

Degradation and partial shading impact the long-term reliability and power production of photovoltaic (PV) modules and power plants. Time-series power ( P mp ) and current–voltage (I-V) curve datastreams from PV modules enable a remote diagnostic approach to quantify active degradation mechanisms and identify partial shading. We study three to nine years of these datastreams, including 3.6 million I-V curves and 36 million P mp values, from eight PV modules, four each of double-glass and glass-backsheet module architectures, located in three distinctly different Koppen-Geiger climate zones, to determine the module’s performance loss rates (PLR), identify active degradation mechanisms and power loss modes, along with partial shading by local objects. Considering both module architectures, PLR results indicate that the BSh climate zone is the most aggressive for module degradation, while the Alpine ET zone is the mildest climate. PLR of double-glass modules located in BWh and BSh climate zones are different due to the significantly greater uniform current loss (ΔPIsc) for double-glass modules in BSh, at a 5% significance level. Power loss for four out of five modules located in the BWh and BSh climates are dominated by uniform current degradation. Statistical analysis of multistep I-V curves detects partial shading experienced by three studied modules with details of the shading profile, the shading Poynting vector diagram for the obstacle’s relative position, shading scenarios, and duration. This work demonstrates how remote monitoring and diagnosis of P mp & I-V time-series of modules can provide quantitative operations and maintenance insights into system performance, degradation mechanisms, and shading.

Nanoindentation and fluorescence spectroscopy provide spatially resolved mechanical and chemical characterization for degradation of poly (ethylene-co-vinyl acetate) (EVA) encapsulants aged under accelerated weathering and in field deployed photovoltaic (PV) modules. For the accelerated weathering tests, two different EVA formulations in the glass/EVA/glass-laminated coupons were exposed to ultraviolet (UV) light for 180 days at three different temperatures (40, 60, and 80 °C) and UV intensities (0.4, 2.2, and 2.9 W/m2/nm at 340 nm). The fluorescence spectra and moduli were uniform through the cross section of both EVA formulations at the lowest temperature and UV intensity; however, under the highest temperature and UV intensity, the UV irradiated sides showed lower moduli and higher fluorescence compared to the opposite sides. For EVA obtained from PV modules deployed 27 years in Sacramento, CA, USA, changes in fluorescence intensity across the thickness were relatively greater than changes in modulus. On the other hand, for EVA obtained from the same type of module stored in the shed for 27 years, no fluorescence was observed, and a uniform modulus was seen through the EVA layer, but with substantially higher values than those obtained from the field-deployed modules. The different extent of changes between laboratory and field exposures suggests the importance of considering effects of temperature and UV intensity for designing a reliable accelerated testing. This study uniquely demonstrates the capability of microscale characterization using nanoindentation and fluorescence microscopy to monitor mechanical and chemical degradation of EVA encapsulants in PV modules.

Fermionic atoms in optical lattices have served as a useful model system in which to study and emulate the physics of strongly correlated matter. Driven by the advances of high-resolution microscopy, the current research focus is on two-dimensional systems1-3, in which several quantum phases-such as antiferromagnetic Mott insulators for repulsive interactions4-7 and charge-density waves for attractive interactions8-have been observed. However, the lattice structure of real materials, such as bilayer graphene, is composed of coupled layers and is therefore not strictly two-dimensional, which must be taken into account in simulations. Here we realize a bilayer Fermi-Hubbard model using ultracold atoms in an optical lattice, and demonstrate that the interlayer coupling controls a crossover between a planar antiferromagnetically ordered Mott insulator and a band insulator of spin-singlets along the bonds between the layers. We probe the competition of the magnetic ordering by measuring spin-spin correlations both within and between the two-dimensional layers. Our work will enable the exploration of further properties of coupled-layer Hubbard models, such as theoretically predicted superconducting pairing mechanisms9,10.

There is often a striking disconnect between communities that create biodiversity frameworks, set targets, and design monitoring system and those that actually implement them. This study aims to (i) develop an integrated (participatory) approach to contextualize available sets of biodiversity indicators to meet specific stakeholders' needs, and (ii) select high-performance and rewarding indicators for participatory forest biodiversity monitoring systems (PFBMS). We used a hierarchical characterization approach to biodiversity to create a global pool of indicators. Specialists then used a framework consisting of multi-tiered filters to select high performance and rewarding indicators from the pool applicable to PFBMS at province and forest management unit levels in Indonesia. Selected indicators are able to reflect changes taking place at various levels in the ecological hierarchy from landscape, habitat, to species level including complete ecosystem attributes, i.e., structural, functional, and compositional. The integrated approach combines the expert guidance and experience of professionals at province and local levels; ensures global-local connection; and follows the participatory approach.

Two decades after the pan-European set of indicators for sustainable forest management was adopted, the European Commission published the New EU Forest Strategy for 2030. We compared the documents on the basis of a content analysis to determine whether they share the same understanding of sustainable forest management. We looked at whether, and to what extent, the existing indicator set is fit for purpose to monitor progress towards the Strategy’s objectives, and the delivery of policy commitments. About two thirds of the identified objectives and commitments in the Strategy can be monitored at least partially by the pan-European set of indicators, whereas new indicators or approaches need to be developed for the remaining third. Several of the indicators are not linked to the Strategy, and some of them are only weakly linked to the policy issues addressed in the Strategy. Our comparison shows a few significant differences between the comprehensive vision of sustainable forest management formulated in the indicator set and the scope of the objectives and commitments in the Strategy. In particular, the forest policy concerns reflected in the Strategy address several issues which are not fully covered in the pan-European indicator set.

It is likely that changing monsoon patterns and changes in other climatic parameters will have an impact on forests. Tree growth and biomass may respond differently across the different forest recovery contexts after the disturbance regimes. It is essential to understand the response of different tree species in order to comprehend their ability to adapt to climate change. An enhanced understanding of how tree species dynamics change with a substantial shift in climate attributes is crucial to develop adaptive forest management strategies. Advances in the statistical application of tree ring data results in more reliable dating with the high accuracy and precision of any of the paleo-records and robust and long-term reconstructions of key indices such as temperature and precipitation. In this study, we analyzed how different species inhabiting together respond to changes in climatic variables using dendroclimatic analysis. We assessed the growth performance of Abies pindrow, Pinus wallichiana, and Tsuga dumosa in the temperate region of Nepal. The climate sensitivity of the species was analyzed using bootstrap correlation analysis and the climate-growth relationship over time was assessed using the moving correlation function. Tree ring growth of Abies pindrow is stimulated by higher June temperatures and higher March precipitation. This positive relationship is consistent and stationary over time. However, in the other two species, both response function and moving correlation analysis showed that the relationship between climate and growth is inconsistent and changes over time.

National climate change policy and strategies set out a framework for planning and undertaking climate change adaptation as well as mitigation activities at the national and local levels. In this article, we examine the coherence and contradictions between national policies and plans, and its impacts on the implementation of adaptation measures at the local level. We undertook a content review of key climate change policy documents (n = 4) of Nepal. In addition, we conducted a field study in the Rajdevi Community Forest User Group (CFUG) located in the mid-hills of Nepal, which has developed and implemented a community level adaptation plan of action (CAPA). The field study involved household interviews, focus group discussions, and an in-depth analysis of CAPA implementation. The paper found that while policies are coherent for targeting highly affected areas and communities, they deviate from discerning an appropriate planning and implanting unit. The local adaptation plan of action (LAPA) considers the local government as an implementing unit, while the national adaptation program of action (NAPA) puts an emphasis on the local community groups. It suggests that the existing LAPA implementation breaches the provision of community-level institutions for the implementation conceived in the central framework. Despite little attention to promoting food security in climate change policy, through the CAPA, local communities have planned and implemented adaptation measures envisioned in the thematic areas identified in the climate change policy of Nepal: agriculture and food security; forests and biodiversity; water resources and energy; climate-induced disasters; public health; and urban settlements and infrastructure. Nevertheless, the CAPA is not institutionalized under government policies and the institutional framework as a local level implementing unit. So, the consensus for a local implementing unit in the policies has remained a key issue. We suggest identifying a suitable and acceptable unit for implementing climate change adaptation at the community level. Only if an appropriate implementing unit is identified can the policies be successful with a broader acceptance and desirable outcomes enshrined in the climate change policy.

In research on photovoltaic (PV) device degradation, current–voltage ( $I$ – $V$ ) datasets carry a large amount of information in addition to the maximum power point. Performance parameters such as short-circuit current, open-circuit voltage, shunt resistance, series resistance, and fill factor are essential for diagnosing the performance and degradation of solar cells and modules. To enable the scaling of $I$ – $V$ studies to millions of $I$ – $V$ curves, we have developed a data-driven method to extract $I$ – $V$ curve parameters and distributed this method as an open-source package in R. In contrast with the traditional practice of fitting the diode equation to $I$ – $V$ curves individually, which requires solving a transcendental equation, this data-driven method can be applied to large volumes of $I$ – $V$ data in a short time. Our data-driven feature extraction technique is tested on $I$ – $V$ curves generated with the single-diode model and applied to $I$ – $V$ curves with different data point densities collected from three different sources. This method has a high repeatability for extracting $I$ – $V$ features, without requiring knowledge of the device or expected parameters to be input by the researcher. We also demonstrate how this method can be applied to large datasets and accommodates nonstandard $I$ – $V$ curves including those showing artifacts of connection problems or shading where bypass diode activation produces multiple “steps.” These features together make the data-driven $I$ – $V$ feature extraction method ideal for evaluating time-series $I$ – $V$ data and analyzing power degradation mechanisms in PV modules through cross comparisons of the extracted parameters.

Soil organic carbon (SOC) plays a crucial role in global carbon cycling. The amount of SOC is influenced by many factors (climate, topography, forest type, forest disturbance, etc.). To investigate this potential effect, we performed a multiple regression model using six different predictor variables in the third national-level forest resource assessment data of Nepal. We found a significant correlation between the SOC and altitude (r = 0.76) followed by crown cover and slope. The altitude alone explains r2 = 58 percent of the variability of the SOC and shows an increasing rate of change of SOC with the increase of altitude. Altitude was identified as a suitable predictor of SOC for large areas with high altitudinal variation followed by crown cover and slope. Increasing amounts of SOC with increasing altitude shows the significance of high-altitude forests in the perspective of climate change mitigation. Altitude, a proxy of temperature, provides insights into the influence of changing temperature patterns on SOC due to future climate change. Further study on forest types and SOC along the altitudinal gradient in Nepal is recommended to deal with the climate change problem in the future.

We study experimentally and theoretically the response of a two-component Fermi condensate in the strongly-interacting regime to a quench of the interaction strength. The quench is realized using a radio-frequency $\pi$-pulse to a third internal level with a different interaction strength. We find that the quench excites the monopole mode of the trap in the hydrodynamic regime and that an initial change of the condensate properties takes place on a time scale comparable or even larger than the quasi-particle relaxation time.

We investigate the response to radio-frequency driving of an ultracold gas of attractively interacting fermions in a one-dimensional optical lattice. We study the system dynamics by monitoring the driving-induced population transfer to a third state, and the evolution of the momentum density and pair distributions. Depending on the frequency of the radio-frequency field, two different dynamical regimes emerge when considering the evolution of the third level population. One regime exhibits (off)resonant many-body oscillations reminiscent of Rabi oscillations in a discrete two-level system, while the other displays a strong linear rise. Within this second regime, we connect, via linear response theory, the extracted transfer rate to the system single-particle spectral function, and infer the nature of the excitations from Bethe ansatz calculations. In addition, we show that this radio-frequency technique can be employed to gain insights into this many-body system coupling mechanism away from equilibrium. This is done by monitoring the momentum density redistributions and the evolution of the pair correlations during the drive. Capturing such non-equilibrium physics goes beyond a linear response treatment, and is achieved here by conducting time-dependent matrix product state simulations., Comment: 19 pages, 24 figures

In an effort to reverse the trend of deforestation and forest degradation, several international initiatives have been attempted. Though promoted in different political arenas, Forest Law Enforcement, Governance and Trade (FLEGT) – Voluntary Partnership Agreement (VPA), and Reducing Emissions from Deforestation and forest Degradation in developing countries (REDD+) share overlapping objectives of conservation of tropical forests. We explore specialists' viewpoint on FLEGT-VPA and REDD+ processes in Indonesia with reference to their contribution towards Sustainable Forest Management (SFM). The study shows that FLEGT-VPA and REDD+ regimes contribute towards SFM. While FLEGT-VPA improves enabling condition for SFM through governance reform, improved harvesting practices, and timber legality assurance system, REDD+ supports SFM through institutional strengthening, reforming policies and frameworks, mobilizing new and additional financial resources and increasing social and ecological resilience. We identified opportunities to achieve synergies between REDD+ and FLEGT-VPA by harmonizing their processes, tools, methodologies, technical assistance, capacity-building and funding mechanisms.

Tree ring analyses can assist in revealing the effect of gradual change in climatic variables on tree growth. Dendroclimatic analyses are of particular importance in evaluating the climate variables that affect growth significantly and in determining the relative strength of different climatic factors. In this study, we investigated the growth performance of Pinus sylvestris, Picea abies, and Pseudotsuga menziesii in northern Germany using standard dendrochronological methods. The study further analyzed tree growth responses to different climatic variables over a period of a hundred years. Both response function analysis and moving correlation analysis confirmed that the climate and growth relationship is species-specific and variable and inconsistent over time. Scots pine and Douglas fir growth were stimulated mainly by the increase in winter temperatures, particularly the January, February, and March temperatures of the current year. In contrast, Norway spruce growth was stimulated mainly by the increase in precipitation in May, June, and July and the increase in temperature in March of the current year. Climate projections for central Europe foresee an increase in temperature and a decrease in the amount of summer precipitation. In a future, warmer climate with drier summers, the growth of Norway spruce might be negatively affected.

As various political initiatives have set goals to reach net-zero emissions by the mid-21st century, forests will play an important role as a carbon sink for sequestering unavoidable emissions. Forest management can take two approaches by either decreasing harvest and enlarging the forest carbon stock or increasing harvest to increase carbon uptake and create harvested wood products (HWPs). Currently, these two management options seem at odds with seemingly conflicting policy directives being written. We used the BEKLIFUH model to assess six management scenarios based on carbon offset potential taking into consideration forest carbon, HWPs and the material and energetic substitution effects. The results show that while conservation leads to a higher above-ground carbon pool, including HWPs, material and energetic substitution leads to more overall carbon offsets for management scenarios with more timber harvesting. With compromise being possible by selectively conserving old growth forests with a high biodiversity value. In conclusion, if the forest sector decouples GHG reporting from forest management and includes all the secondary effects of timber harvest, this new approach can lead to a different cost–benefit analysis for the choice between harvest vs. conservation. This could result in a paradigm shift to a future where biodiversity and carbon neutrality can coexist.

Reducing Emissions from Deforestation and Degradation (REDD+) has been identified as a potentially cost-effective climate change mitigation strategy. The success of REDD+ in preventing deforestation and degradation in dry forests will depend partly on whether financial incentives for forest conservation can cover smallholders' opportunity costs of forgone uses of the forest. We therefore compared the opportunity costs of the main forest use activities (slash-and-burn agriculture or charcoal production) with potential benefits from the sale of carbon credits under REDD+ from a smallholder perspective for a case study in southwestern Madagascar. Calculations are based on an assessment of carbon stocks in the dry spiny forests as well as benefit and cost data from interviews with smallholders. To assess the risks and uncertainties associated with opportunity costs and the REDD+ benefits, we used a Monte Carlo modeling approach. We compare net present values for opportunity costs and potential community profits from REDD+ at discount rates of 5% and 20% over a project period of 25 years. Our results show that REDD+ community profits can outweigh the profits from charcoal production and the profits from slash-and-burn agriculture in 54–57% of the cases, despite opportunity costs being highly variable for both land uses. Charcoal production in particular has low opportunity costs as smallholders only engage in this activity when no other sources of income are available. The case study shows that potential REDD+ payments can provide sufficient financial incentives to preserve dry forests with low carbon stocks but relatively low opportunity costs of preservation.

Higgs and Goldstone modes are possible collective modes of an order parameter upon spontaneously breaking a continuous symmetry. Whereas the low-energy Goldstone (phase) mode is always stable, additional symmetries are required to prevent the Higgs (amplitude) mode from rapidly decaying into low-energy excitations. In high-energy physics, where the Higgs boson has been found after a decades-long search, the stability is ensured by Lorentz invariance. In the realm of condensed--matter physics, particle--hole symmetry can play this role and a Higgs mode has been observed in weakly-interacting superconductors. However, whether the Higgs mode is also stable for strongly-correlated superconductors in which particle--hole symmetry is not precisely fulfilled or whether this mode becomes overdamped has been subject of numerous discussions. Experimental evidence is still lacking, in particular owing to the difficulty to excite the Higgs mode directly. Here, we observe the Higgs mode in a strongly-interacting superfluid Fermi gas. By inducing a periodic modulation of the amplitude of the superconducting order parameter $\Delta$, we observe an excitation resonance at frequency $2\Delta/h$. For strong coupling, the peak width broadens and eventually the mode disappears when the Cooper pairs turn into tightly bound dimers signalling the eventual instability of the Higgs mode.

The “Fit for 55” climate package adopted by the EU is intended to prepare the way for the EU's climate neutrality in 2050. It contains measures affecting the forestry and timber sector. We evaluate three instruments: the proposal for a New EU Forest Strategy for 2030, the EU Renewable Energy Directive and the Land-use, Land-Use Change and Forestry Regulation with regard to their implications for sustainable forest management. The demands that the three instruments impose on forest management are not coherent and are dominated by ecological aspects as well as by the intention to increase the forest C-pool. As they lack a holistic view, they do not meet the requirements of multifunctional, sustainable forest management.