Abstract. Forests play a crucial role in Europe as carbon sinks, biodiversity reservoirs, and sources of renewable raw materials. Reliable Europe-wide statistics on forest biomass stocks, forest area, and harvest at national and subnational scales are essential for monitoring biomass dynamics and supporting sustainable forest management. However, the availability of such data remains incomplete, and differences in definitions, methodologies, and reporting standards introduce substantial uncertainties that hinder robust interpretation. Here, we present EuFor, an open-access database of key forest indicators for 38 European countries, derived from National Forest Inventories (NFIs), census statistics, and datasets from international organizations. It is openly available at https://doi.org/10.5281/zenodo.20815146. EuFor consists of two subsets: (i) EuFor-reported, a compilation of primary statistical data for 1990–2023, and (ii) EuFor-harmonized, a stock-flow consistent annual time series of forest area, roundwood volumes of growing stock and harvest for 2000–2023 across 21 national and 193 subnational units. EuFor shows near-perfect agreement with an authoritative reference dataset at the European aggregate level. At the country level, however, discrepancies vary substantially. Agreement is highest for forest area (mean relative deviation: 3.2 %; mean Pearson correlation: r = 0.743), followed by growing stock (7.4 %; r = 0.872), and harvest (14.5 %; r = 0.654). We further derived four indicators of forest-use intensity. Data uncertainties propagated into these estimates, leaving the direction of change ambiguous in 20 % of assessments. Moreover, the indicators often revealed contrasting spatial patterns and trends, highlighting both substantial uncertainty in trend interpretation and the multidimensional nature of forest-use intensity. By providing open-access, harmonized forest statistics together with an explicit assessment of uncertainty, EuFor offers a valuable resource for future analyses of forest biomass dynamics, carbon balances, forest-use intensity, and sustainable forest management across Europe.

Der Zweite Österreichische Sachstandsbericht zum Klimawandel ist die derzeit größte und wichtigste interdisziplinäre Analyse der Klimawandelfolgen und Darstellung von Handlungsoptionen in Österreich. Ziel ist es, fundierte Informationen über beobachtete und erwartete Klimaänderungen, deren Folgen sowie über Optionen zur Emissionsreduktion und Anpassungsstrategien bereitzustellen. Der Bericht zeigt Handlungsspielräume, aber gibt keine Empfehlungen für oder gegen konkrete Einzelmaßnahmen. Stattdessen zeigt der Bericht Risiken, Chancen, Hindernisse, Zielkonflikte und Synergien zwischen Klimaschutz, Anpassung und anderen gesellschaftlichen Prioritäten wie der Erreichung der Ziele für nachhaltige Entwicklung (Sustainable Development Goals, SDGs) auf. Der Bericht wurde nach den Methoden und Abläufen des Weltklimarats (IPCC) von über 200 Wissenschaftler:innen an mehr als 50 Institutionen verfasst. Ein wissenschaftlicher Review-Prozess folgte einem strengen, mehrstufigen Ansatz basierend auf den IPCC-Richtlinien, um die höchsten Qualitätsstandards für diesen Sachstandsbericht zu gewährleisten. Dieser öffentlich zugängliche Prozess förderte eine breite Beteiligung der Forschungsgemeinschaft und umfasste über 100 externe Gutachter:innen. Dadurch wurde sichergestellt, dass der Sachstandsbericht die wissenschaftliche Literatur umfassend, klar und konsistent aufbereitet. Mit rund 800 Seiten bildet der Sachstandsbericht eine umfassende wissenschaftliche Grundlage zum Klimawandel in Österreich. Der Bericht wurde in englischer Sprache geschrieben, die Zusammenfassungen wurden ins Deutsche übersetzt. Ermöglicht wurde der Sachstandsbericht durch eine Förderung des Klima- und Energiefonds aus Mitteln des Bundesministeriums für Land- und Forstwirtschaft, Klima- und Umweltschutz, Regionen und Wasserwirtschaft.

Land use is intimately linked to key components of the Earth system, including the climate system, biodiversity and biogeochemical cycles. Advanced understanding of patterns and dynamics of land use is vital for assessing impacts on these system components and for developing strategies to ensure sustainability. However, thematically detailed data that enable the analyses of spatiotemporal dynamics of land use, including land-use intensity, are currently lacking. This study presents a comprehensive land-use data cube (LUIcube) that traces global land-use area and intensity developments between 1992 and 2020 annually at 30 arcsecond spatial resolution. It discerns 32 land-use classes that can be aggregated to cropland, grazing land, forestry, built-up land and wilderness. Land-use intensity is represented through the framework of Human Appropriation of Net Primary Production, which allows to quantify changes in NPP, respectively biomass flows, induced by land conversion and land-management. The LUIcube provides the necessary database for analyzing the role of natural and socioeconomic drivers of land-use change and its ecological impacts to inform strategies for sustainable land management.

Despite broad scientific consensus on the urgent need to rapidly reduce greenhouse gas emissions, the question of how to achieve this remains contested. Existing proposals emphasize either supply-side or demand-side strategies, yet conceptual integration between the two is rare. This article develops a typology for climate change mitigation research by distinguishing two key dimensions: the primary entry point of intervention (supply-side vs. demandside) and the dominant scope of intervention (individual vs. systemic). Within this typology, we identify four research perspectives - techno-innovation, individual decision-making, industrial transformation, and embedded lifestyles - and compare them in terms of their problem framings, disciplinary origins, forms of intervention, policy proposals, and target actors. Our typology shows that while mitigation strategies have become more diverse, they still tend to prioritize either supply-side or demand-side interventions, rather than integrating them as complementary pathways for social-ecological transformation. To address this gap, we propose three promising research directions: provisioning systems, sufficiency corridors, and social-ecological practices. These directions (1) analyze production and consumption as coupled systems, challenging the traditional supply-demand dichotomy; (2) frame climate change mitigation not only as a technological challenge but also as a call for absolute reductions in production and consumption; and (3) pursue transformative change on a systemic level, moving beyond the cumulative effects of individual decisions by emphasizing collective, rules-based interventions.

Understanding the trends and distribution of greenhouse gas (GHG) emissions embodied in household consumption is pivotal to developing climate-change mitigation strategies that are just and effective. While household GHG footprints inequality is increasingly investigated, less is known about its temporal dynamics across product groups. For the case of Austria, we (1) develop a database for household GHG footprints from 2000 to 2020 by combining multi-regional input–output modeling with household budget surveys, (2) investigate temporal trends across consumption categories and income groups, and (3) explore socio-economic explanatory variables. We find that the sum of Austrian household GHG footprints declined from 73 Mt CO2eq in 2000 to 67 Mt CO2eq in 2020. In 2005, when Austrian GHG emissions peaked, the highest income decile induced 3.5 times more GHG emissions than the lowest income decile. This factor remained similarly high at 3.4 until 2020, particularly due to trends in the consumption categories mobility and goods. The most notable GHG reduction was achieved in housing/heating, where carbon inequality was less pronounced. Beyond income, floor space, car ownership, the heating system, household size, and the number of vacations significantly affect GHG footprints. Our findings suggest that reducing stubbornly high carbon inequality, particularly in the consumption of mobility and goods, can contribute to more effective climate-change mitigation.

The U.S. have committed to a 35 % decrease of non-CO2 greenhouse gas (GHG) emissions (CH4, N2O) by 2030. Around half of these emissions stem from the AFOLU sector (agriculture forestry, and other land-use), while forests sequester CO2 through biomass growth. Efforts have centred on efficiency improvements to decouple biomass production from emissions. The goal of this study is to 1.) quantify the AFOLU sector's production and GHG dynamics between 1910 and 2022, 2.) conduct a decoupling analysis of sectoral and product trends, yearly and cumulatively, 3) evaluate how past and ongoing trends of decoupling compare to land-based climate mitigation targets. Key GHG emission sources include livestock and crop production. The AFOLU sector's annual GHG balance fluctuated between sinks and sources but cumulatively the sector emitted slightly less (42,914 Megatonnes CO2 equivalents, MtCO2e) than it sequestered (-44,130 MtCO2e). Partial decoupling was achieved, driven by forestry dynamics, efficiency gains in livestock production, and shifts to less emission-intensive products. However, decoupling has been inconsistent, and increased agricultural production has offset efficiency gains. To achieving climate targets solely through decoupling would require emissions to fall 50 % stronger than they currently do. Our findings support research suggesting that sufficiency measures e.g. reducing livestock production and consumption are necessary to decouple food provision from GHG emissions.

Demand-side options are increasingly recognized for their potential to mitigate climate change while reducing reliance on novel carbon dioxide removal. However, systematic analyses of implemented demand-side mitigation policy mixes remain scarce, compromising assessment and exploration of effective and feasible demand-side policies. Here, we provide a multilevel analysis of the evolution, composition, and foci of demand-side mitigation policy mixes in the transport and housing sector from 1995 to 2024, focusing on the EU, the federal Austrian level and two provincial levels (Vienna, Lower Austria). Our high-resolution policy database features 356 demand-side measures, systematically classified according to policy target, instrument type, and the avoid-shift-improve framework. We find that existing policy mixes heavily rely on shift and improve measures, critically neglecting mitigation potentials of avoid options as well as certain policy areas. This suggests an urgent need to broaden demand-side policy mixes and explore strategies that increase the political feasibility of avoid options.

Wood use is crucial for climate-change mitigation, but strategies range from increasing harvest to conserving forests. To reconcile contradictions, we conceptualize an option space that considers both social and ecological thresholds. We couple the material flow model RECC and the forest model CRAFT to quantify the option space for wood use in the global building sector and current forest areas from 2020 to 2050. We juxtapose four demand scenarios with four supply scenarios that meet material and ecosystem service thresholds, respectively. In 12 of the 16 resulting scenario combinations, supply exceeds demand. They differ in regional self-sufficiency (6-9 out of ten world regions), average primary wood availability beyond structural timber use (0.2-1.4 GtCyr-1), and overall climate impacts (2.0-8.0 GtCO2eqyr-1). Substantially increasing wood intensity in buildings within ecological limits is only feasible in a low floorspace scenario with increasing circularity, emphasizing the need for nuance in claims regarding the sustainability of wood use.

Summary The concept of a forest transition – a regional shift from deforestation to forest recovery – tends to equate forest area expansion with sustainability, assuming that more forest is good for people and the environment. To promote debate and more just and ecologically sustainable outcomes during this period of intense focus on forests (such as the United Nations’ Decade on Ecological Restoration, the Trillion Trees initiative and at the United Nations’ Climate Change Conferences), we synthesize recent nuanced and integrated research to inform forest management and restoration in the future. Our results reveal nine pitfalls to assuming forest transitions and sustainability are automatically linked. The pitfalls are as follows: (1) fixating on forest quantity instead of quality; (2) masking local diversity with large-scale trends; (3) expecting U-shaped temporal trends of forest change; (4) failing to account for irreversibility; (5) framing categories and concepts as universal/neutral; (6) diverting attention from the simplification of forestlands into single-purpose conservation forests or intensive production lands; (7) neglecting social power transitions and dispossessions; (8) neglecting productivism as the hidden driving force; and (9) ignoring local agency and sentiments. We develop and illustrate these pitfalls with local- and national-level evidence from Southeast Asia and outline forward-looking recommendations for research and policy to address them. Forest transition research that neglects these pitfalls risks legitimizing unsustainable and unjust policies and programmes of forest restoration or tree planting.

Rapidly progressing climate heating as well as ongoing economic and population growth exacerbate the challenges of reconciling the multitude of land functions and services. Terrestrial ecosystems support biodiversity and climate regulation and deliver resources like food, energy, or fiber, while infrastructures proliferate. Navigating the resulting “global land squeeze” aims to maintain a healthy biosphere while supporting land-based services for a decent living for us all. To elucidate trade-offs and synergies related to the global land squeeze, we discuss key components of the land system and their interplay, trade-offs, past trends, and current geographical patterns. We examine three social-science concepts and explore their suitability for navigating the land squeeze and identify demand-side strategies, like reducing overconsumption, that may emerge as no-regret solutions in industrialized contexts. We conclude that enhancing the analytical capabilities to steer land system change requires shifting from isolated driver-impact analyses toward the ex ante integration of societal and ecological sustainability targets on an equal footing.

Zusammenfassung Kap. 2 beschreibt die Auswirkungen der Landnutzung und -bewirtschaftung auf den Klimawandel und bezieht nicht bewirtschaftete Ökosysteme explizit mit ein. Das zentrale Instrument für die Bilanzierung der Auswirkungen der österreichischen Landnutzung auf den Klimawandel ist die Treibhausgasinventur (THG-Inventur), die jährlich basierend auf international akkordierten Methoden erfasst und publiziert wird. Neben der Präsentation und Diskussion der Ergebnisse der THG-Inventur für die beiden Sektoren Landwirtschaft sowie Landnutzung, Landnutzungswechsel und Forstwirtschaft (LULUCF; beide Sektoren zusammen auch als AFOLU, für Agriculture, Forestry and Other Land Use, abgekürzt) werden in weiteren Abschnitten andere Aspekte, die zum Verständnis der Klimawirksamkeit von Landnutzung und Landbewirtschaftung auf den Klimawandel beitragen, vorgestellt.

Emissions from agricultural activities constitute 11% of global greenhouse gas emissions and are hard to abate. Here, we present and analyze a consistent empirical assessment of global emissions from agricultural activities from 1910–2015. Agricultural emissions increased 3.5-fold from 1910–2015, from 1.9 to 6.7 GtCO _2 eq yr ^−1 . CH _4 emissions, emissions from enteric fermentation and from livestock products contributed the highest fractions of emissions by gases, processes, and products, respectively. A decomposition analysis quantifies the contribution of major drivers of agricultural emissions dynamics. It reveals that globally and across the entire period, changes in population, agricultural production per capita (‘output’), regional distribution of production (‘regional mix’), and composition of final products (‘product mix’, i.e. a shift towards livestock production) all contributed to increasing agricultural emissions. Conversely, declining emissions per unit of production (‘emissions intensity’), particularly for livestock, partly counterbalanced the emissions increase. Significant variations prevail across regions and time periods. Most notably, the composition of final products counteracted agricultural emissions increase from 1910–1950, but growing livestock production has become an increasingly important driver of emissions growth in more recent periods. This finding unravels that increases in livestock production offset the improvements in emissions intensity of industrial agricultural intensification. Our findings underscore the large potential of reducing livestock production and consumption for mitigating the climate impacts of agriculture.

Forests play a crucial role in achieving net-zero greenhouse gas emission targets in the coming decades, as they can act as natural carbon sinks by removing carbon dioxide from the Earth's atmosphere. The use of wood as a building material leads to lower greenhouse gas (GHG) emissions throughout its life cycle compared to other building materials and is therefore considered a valid climate change mitigation strategy. However, the impact of wood harvesting on the potential carbon storage in forests has largely been ignored. In this study, we investigated whether the use of wood as a building material is beneficial for climate change mitigation when considering carbon opportunity costs, which represent the amount of carbon prevented from accumulating in forests due to wood extraction. We introduce the climate optimum concept, which links both GHG emission substitution and associated carbon opportunity cost of wooden buildings. Application of the concept to a case study building shows that the GHG substitution benefits of wooden buildings for climate change mitigation are overshadowed by carbon opportunity costs in forests. In our analysis, no wooden scenario achieves sufficient life cycle embodied GHG emission substitution in order to compensate for the unrealized carbon storage potential in the forest system due to harvest. Wood-based GHG mitigation strategies in the building sector and beyond need to consider this unrealized carbon storage potential of forests expressed via carbon opportunity costs, in order to obtain a more comprehensive picture of the climate impact of forests and wood-based products.

Agriculture is an important contributor to greenhouse gas (GHG) emissions. While the development of agricultural GHG emissions on national and global scales is well studied for the last three to six decades, little is known about their trajectory and drivers over longer periods. In this article, we address this research gap by calculating and analyzing GHG emissions related to agriculture in Austria from 1830 to 2018. We calculate territorial emissions on an annual basis and include all GHG emissions from the processes directly involved in agricultural production. Based on this time series, we quantify the relative importance of major drivers of changes in GHG emissions across time and agricultural product categories, applying a structural decomposition analysis. We find that agricultural GHG emissions in Austria increased by 69 % over the total study period, from 4.6 Mt. CO2e/yr in 1830 to 7.7 Mt. CO2e/yr in 2018. While emissions increased only moderately from 1830 to 1945 (+22 % overall), with strong fluctuations between 1914 and 1945, they doubled from 1945 to 1985. In the most recent period from 1985 to 2018, emissions fell by one third, with decreases leveling off over time. Our decomposition analysis reveals that increases in agricultural production per capita most importantly contributed to the high growth in GHG emissions from 1945 to 1985. Conversely, decreasing emission intensities of products and a more climate friendly product mix were key drivers in the emissions reduction observed after 1985. We also contribute to the discussion around the global warming potential star (GWP*), by calculating GHG emissions based on this alternative metric, and contextualize our data within total socio-economic GHG emission trends. By providing insights into the historical trends and drivers of agricultural GHG emissions, our findings enhance the understanding of their long-term historical dynamics and adds to the knowledge base for future mitigation efforts.

The importance of international timber trade in The United States forest transition is poorly understood. Here, we synthesize a variety of historical sources to establish a consistent socio-metabolic dataset for U.S. physical trade in timber and timber products from 1870 to 2017, distinguishing three product categories (raw, primary and final products) and major trading partners. The United States increasingly relied on net imports of primary and final timber products, mainly from Canada, but also from Asia, and Europe, while emerging as a net-exporter of raw timber. The growing physical import dependence coincided with domestic forest recovery, indicating that imports contributed to reducing pressures on domestic forests. The structure of timber trade suggests that the United States also outsourced labor for wood processing.

Zusammenfassung Die Technische Zusammenfassung des APCC-Sonderberichts ″Landnutzung und Klimawandel in Österreich″ umfasst die Kernbotschaften der Kapitel 1–9. In ihr sind die Hauptaussagen zu den sozioökonomischen und klimatischen Treibern der Landnutzungsänderungen, zu den Auswirkungen von Landnutzung und -bewirtschaftung auf den Klimawandel, zu Minderungs- und Anpassungsoptionen im Kontext nachhaltiger Entwicklungsziele sowie zu Synergien, Zielkonflikten und Umsetzungsbarrieren von Klimamaßnahmen enthalten.

Societal activities massively alter the global carbon (C) cycle, thereby driving global climate heating. Socioeconomic material stocks - e.g. in buildings and infrastructures - have been identified as a C pool that can potentially store increasing amounts of C, thereby keeping C away from the atmosphere. However, little is known about the size, composition, distribution and development of global socioeconomic C stocks. Based on an established economy-wide C accounting approach from sociometabolic research, we consistently and comprehensively quantified the C contained in eight components of socioeconomic stocks in the period 1900–2015 at the level of nine world regions. We discern inert (aggregates and other gravel) and ‘active’ climate-relevant (i.e. biomass and fossil-fuel based) C pools. We find that global active components of socioeconomic C stocks grew by a factor of 9, from 1.9 (1.5–2.2) Pg of carbon (PgC) to 16.8 (13.7–20.2) PgC. The inert socioeconomic C stock in aggregates & other gravel amounted to 25.2 (6.1–48.0) PgC in 2015, however with high uncertainties. Absolute annual net additions to stock (NAS) of active stock components was 0.49 (0.40–0.59) PgC yr ^−1 which equaled 5% of the C emissions from fossil fuel combustion and industrial processes. However, raising NAS of components with biomass feedstock that sequester C from the atmosphere comes with biodiversity and food security trade-offs. This study contributes to a holistic perspective on social and natural C stocks that acknowledges their interactions. The global socioeconomic C stock reached a geologically relevant extent (approximately the size of C in coasts) and should therefore be integrated in the assessments of the global C cycle to acknowledge the Anthropocene.