Photovoltaic modules are exposed to a variety of climatic loads during outdoor operation. Over time, these loads trigger a number of degradation modes within the modules leading to performance loss. This paper quantifies the impact of combined climatic loads on the module's maximum power output using a mathematical approach. Three degradation precursor reactions, namely, hydrolysis, photodegradation, and thermomechanical degradation, are assumed to be necessary for service lifetime prediction. For each reaction, an empirical kinetics model is proposed and validated with indoor test measurements. A generalized model to quantify the effects of combined climatic loads is proposed. The generalized model is calibrated and validated using outdoor test measurements. The model is then applied to predict the annual degradation rates and a 20% performance loss of three identical monocrystalline modules installed in three benchmarking climates: maritime (Gran Canaria, Spain), arid (Negev, Israel), and alpine (Zugspitze, Germany) using real monitored meteorological data. A degradation of 0.74%/year corresponding to 21.4 years operation time was predicted as the highest for an arid environment, compared with 0.50%/year and 0.3%/year degradation for maritime and alpine environments, respectively. The proposed models will find applications in outdoor predictions as well as in the combined stress accelerated tests to develop test designs.

The world’s forests play a pivotal role in the mitigation of global climate change. By photosynthesis they remove CO₂ from the atmosphere and store carbon in their biomass. While old trees are generally acknowledged for a long carbon residence time, there is no consensus on their contribution to carbon accumulation due to a lack of long-term individual tree data. Tree ring analyses, which use anatomical differences in the annual formation of wood for dating growth zones, are a retrospective approach that provides growth patterns of individual trees over their entire lifetime. We developed time series of diameter growth and related annual carbon accumulation for 61 trees of the species Cedrela odorata L. (Meliacea), Hymenaea courbaril L. (Fabacea) and Goupia glabra Aubl. (Goupiacea). The trees grew in unmanaged tropical wet-forests of Suriname and reached ages from 84 to 255 years. Most of the trees show positive trends of diameter growth and carbon accumulation over time. For some trees we observed fluctuating growth—periods of lower growth alternate with periods of increased growth. In the last quarter of their lifetime trees accumulate on average between 39 percent (C. odorata) and 50 percent (G. glabra) of their final carbon stock. This suggests that old-growth trees in tropical forests do not only contribute to carbon stocks by long carbon resistance times, but maintain high rates of carbon accumulation at later stages of their life time.

The density of wood is a key indicator of the carbon investment strategies of trees, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here we analyse information from 1.1 million forest inventory plots alongside wood density data from 10,703 tree species to create a spatially explicit understanding of the global wood density distribution and its drivers. Our findings reveal a pronounced latitudinal gradient, with wood in tropical forests being up to 30% denser than that in boreal forests. In both angiosperms and gymnosperms, hydrothermal conditions represented by annual mean temperature and soil moisture emerged as the primary factors influencing the variation in wood density globally. This indicates similar environmental filters and evolutionary adaptations among distinct plant groups, underscoring the essential role of abiotic factors in determining wood density in forest ecosystems. Additionally, our study highlights the prominent role of disturbance, such as human modification and fire risk, in influencing wood density at more local scales. Factoring in the spatial variation of wood density notably changes the estimates of forest carbon stocks, leading to differences of up to 21% within biomes. Therefore, our research contributes to a deeper understanding of terrestrial biomass distribution and how environmental changes and disturbances impact forest ecosystems.

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.

At the 15th Conference of Parties of the UN Framework Convention on Climate Change, Copenhagen, 2009, harvested wood products were identified as an additional carbon pool. This modification eliminates inconsistencies in greenhouse gas reporting by recognizing the role of the forest and timber sector in the global carbon cycle. Any additional CO2-effects related to wood usage are not considered by this modification. This results in a downward bias when the contribution of the forest and timber sector to climate change mitigation is assessed. The following article analyses the overall contribution to climate protection made by the forest management and wood utilization through CO2-emissions reduction using an example from the German state of North Rhine-Westphalia. Based on long term study periods (2011 to 2050 and 2100, respectively). Various alternative scenarios for forest management and wood usage are presented. In the mid- to long-term (2050 and 2100, respectively) the net climate protection function of scenarios with varying levels of wood usage is higher than in scenarios without any wood usage. This is not observed for all scenarios on short and mid term evaluations. The advantages of wood usage are evident although the simulations resulted in high values for forest storage in the C pools. Even the carbon sink effect due to temporal accumulation of deadwood during the period from 2011 to 2100 is outbalanced by the potential of wood usage effects. A full assessment of the CO2-effects of the forest management requires an assessment of the forest supplemented with an assessment of the effects of wood usage. CO2-emission reductions through both fuel and material substitution as well as CO2 sink in wood products need to be considered. An integrated assessment of the climate protection function based on the analysis of the study’s scenarios provides decision parameters for a strategic approach to climate protection with regard to forest management and wood use at regional and national levels. The short-term evaluation of subsystems can be misleading, rendering long-term evaluations (until 2100, or even longer) more effective. This is also consistent with the inherently long-term perspective of forest management decisions and measures.