Biofuel systems may represent a promising strategy to combat climate change by replacing fossil fuels in electricity generation and transportation. First-generation biofuels from sugar and starch ...crops for ethanol (a gasoline substitute) and from oilseed crops for biodiesel (a petroleum diesel substitute) have come under increasing levels of scrutiny due to the uncertainty associated with the estimation of climate change impacts of biofuels, such as due to indirect effects on land use. This analysis estimates the magnitude of some uncertainty sources: i) crop/feedstock, ii) life cycle assessment (LCA) modelling approach, iii) land-use change (LUC), and iv) greenhouse gas (GHG) metrics. The metrics used for characterising the different GHGs (global warming potential-GWP and global temperature change potential-GTP at different time horizons) appeared not to play a significant role in explaining the variance in the carbon footprint of biofuels, as opposed to the crop/feedstock used, the inclusion/exclusion of LUC considerations, and the LCA modelling approach (p<0.001). The estimated climate footprint of biofuels is dependent on the latter three parameters and, thus, is context-specific. It is recommended that these parameters be dealt with in a manner consistent with the goal and scope of the study. In particular, it is essential to interpret the results of the carbon footprint of biofuel systems in light of the choices made in each of these sources of uncertainty, and sensitivity analysis is recommended to overcome their influence on the result.
Agriculture provides the largest share of food supplies and ensures a critical number of ecosystem services (e.g., food provisioning). Therefore, agriculture is vital for food security and supports ...the Sustainable Development Goal (SDGs) 2 (SDG 2 - zero hunger) as others SDG's. Several studies have been published in different world areas with different research directions focused on increasing food and nutritional security from an agricultural land system perspective. The heterogeneity of the agricultural research studies calls for an interdisciplinary and comprehensive systematization of the different research directions and the plethora of approaches, scales of analysis, and reference data used. Thus, this work aims to systematically review the contributions of the different agricultural research studies by systematizing the main research fields and present a synthesis of the diversity and scope of research and knowledge. From an initial search of 1151 articles, 260 meet the criteria to be used in the review. Our analysis revealed that most articles were published between 2015 and 2019 (59%), and most of the case studies were carried out in Asia (36%) and Africa (20%). The number of studies carried out in the other continents was lower. In the last 30 years, most of the research was centred in six main research fields: land-use changes (28%), agricultural efficiency (27%), climate change (16%), farmer's motivation (12%), urban and peri-urban agriculture (11%), and land suitability (7%). Overall, the research fields identified are directly or indirectly linked to 11 of the 17 SDGs. There are essential differences in the number of articles among research fields, and future efforts are needed in the ones that are less represented to support food security and the SDGs.
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•Agricultural land systems research is centred on six main subjects.•Agriculture land systems is relevant to 11 of the 17 SDGs.•Limited studies on climate adaptation, land management and land suitability subjects•Developed regions are underrepresented in this scientific domain.•Agricultural land systems research is important to food security.
The adoption of a catchment-to-coast management approach is critical to prevent the continued loss of ecosystem functionality in small temporarily closed estuaries (TCEs). This study investigated the ...impact of anthropogenic pressures on the water quality (i.e., inorganic N and P, dissolved oxygen) and phytoplankton community dynamics of 55 TCEs situated along the subtropical coastline of KwaZulu-Natal, South Africa. Extensive spatial surveys were conducted in summer (high flow) and winter (low flow) to capture variability associated with open (84%; n = 46) and closed (73%; n = 40) mouth conditions, respectively. The health of the TCEs in this region are severely threatened (‘High’ or ‘Very High’ ratings) by pollution (67%) and habitat loss (53%) pressures. Wastewater effluent discharges are a key source of pollution, with 25 of the study estuaries receiving substantial combined annual inflow volumes (44 × 106 m3) and inorganic nutrient loads (352,900 kg DIN; 222,200 kg DIP) from upstream wastewater treatment plants. The loss of habitat in these small TCEs stems from high levels of catchment land-use modifications (∼50% transformed), with agricultural (e.g., sugarcane farming, commercial forestry) and development (e.g., built-up, informal) activities accounting for 35% and 12% of overall land-use, respectively. The impact of these pressures is highlighted by the relatively high proportion of TCEs exhibiting eutrophic levels of inorganic nutrients during the high (DIN: 25%, n = 14; DIP: 18%, n = 10) and low (DIN: 31%, n = 17; DIP: 26%, n = 14) inflow periods. Despite this, estuarine phytoplankton bloom conditions (>20 μg Chl-a l−1) are sporadic due to the limited tidal exchange (perched mouths) and low water residency (augmented baseflows) that characterise these TCEs. As such, anthropogenic perturbations serve to dampen the role of estuarine primary producers as nutrient buffers in subtropical TCEs, thus promoting the export of excessive nutrient loads to the adjacent coastal waters. Catchment-scale interventions should be geared towards effective governance, infrastructure maintenance, and implementation of restoration activities (e.g., diversion and/or reuse of wastewater discharges) to improve the health and biodiversity of small, microtidal TCEs.
•Microtidal temporarily closed estuaries (TCEs) are vulnerable to human perturbations.•Pollution and habitat loss threaten the health of South African subtropical TCEs.•Wastewater discharges are a key driver of eutrophic responses in subtropical TCEs.•Flow alterations and limited tidal exchange aid nutrient export to coastal waters.•Catchment-scale interventions will improve the health of these vulnerable systems.
Around 9% of global CO2 emissions originate from land use changes. Often, these emissions are not appropriately addressed in Life Cycle Assessment. The link between demand for crops in one region and ...impacts in other regions is referred to here as indirect land use change (iLUC) and includes deforestation, intensification and reduced consumption. Existing models for iLUC tend to ignore intensification and reduced consumption, they most often operate with arbitrary amortisation periods to allocate deforestation emissions over time, and the causal link between land occupation and deforestation is generally weakly established. This paper presents the conceptual framework required for a consistent modelling of iLUC in Life Cycle Assessment. It reports on a novel and biophysical iLUC model, in which amortisation is avoided by using discounted Global Warming Potentials (GWPs). The causal link between demand for land and land use changes is established through markets for land's production capacity. The iLUC model presented is generally applicable to all land use types, crops and regions of the world in typical LCA decision-making contexts focusing on the long-term effects of small-scale changes. The model's strengths and weaknesses are discussed.
•The iLUC model is applicable to all land uses in all regions of the world.•The model considers both land use changes and intensification.•The model is based on consistent life cycle inventory modelling principles.•Consequential and attributional modelling assumptions can be applied in the model.
Under global climate change and pressure from human activities, water scarcity is becoming a major concern in the quest for regional sustainable development in the Yellow River Basin (YRB). This ...study integrates scenarios of climate change and human activities under the Representative Concentration Pathway (RCP4.5 and RCP8.5) with a watershed-scale hydrological model, and uses the Water Use-to-Availability Ratio (WUAR) to study future water scarcity over six sub-catchments in the YRB. It further investigates the relationship between the future water scarcity and hydroclimatic and anthropogenic drivers. The results suggest that the average WUAR under both RCP4.5 and RCP8.5 will likely exceed the water scarcity threshold (WUAR >20%) and will reach up to 39.9 and 44.7%, respectively. The average WUAR for the upstream and downstream sub-catchments will likely range from 23.8 to 51.6% under RCP4.5 and from 25.5% to 73.8% under RCP8.5, indicating moderate to severe and moderate to extreme water scarcity, respectively. Future WUAR correlates negatively (r-value = −0.85) with the streamflow drought index (SDI) in the upstream sub-catchments, i.e., hydrological drought will likely intensify water scarcity. Conversely, WUAR and SDI would be positively correlated (r-value = +0.70) in the downstream sub-catchments, i.e., water scarcity will become severer despite decreasing severity of hydrological drought. Under climate change, water scarcity in these sub-catchments will exhibit high dependency (Kendall τ correlation coefficient = 0.84) on water-use patterns than on water availability. The regression analysis indicates that the WUAR will increase significantly (p < 0.05) with projected woodland, cropland, and buildup areas under RCP4.5. This relationship will become even more significant (p < 0.01) under RCP8.5. This study provides insights into the potential drivers of future water scarcity in the YRB, which is likely to confront water supply crises. The study should help policymaking towards attaining sustainable water management in the basin.
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•Future water scarcity is projected considering human activities and climate change impacts.•Moderate to severe water scarcity is expected over six Yellow River sub-catchments under the RCP4.5 scenario.•The severity of water scarcity under RCP8.5 is 11.7% higher than that under RCP4.5.•The human influences on water scarcity will be worse than that of climate change.•Water availability in the downstream will likely be impacted by concurrent changes in land-use and high temperature.
AIM: To assess the effects of climate change, past land uses and physiography on the current position of the tree line in the Catalan Pyrenees and its dynamics between 1956 and 2006. LOCATION: More ...than 1000 linear kilometres of sub‐alpine tree line in the Catalan Pyrenees (north‐east Spain) METHODS: Using aerial photographs and supervised classification, we reclassified the images into a binary raster with ‘tree’ and ‘non‐tree’ values, and determined canopy cover in 1956 and 2006. We then determined the change in position of the tree line between 1956 and 2006 based on changes in forest cover. We used the distance from the position of the tree line in 1956 to the theoretical potential tree line – determined from interpretation of aerial photographs, identifying the highest old remnants of forest for homogeneous areas of the landscape in terms of bioclimatic conditions, bedrock, landform and exposure – as a surrogate of intensity of past land uses. RESULTS: Our analyses showed that the Pyrenean tree line has moved upwards on average almost 40 m (mean advance ± SE: 35.3 ± 0.5 m, P < 0.001), although in most cases it has remained unchanged (61.8%) or advanced moderately, i.e. between 25 and 100 m (23.7%); only 9.2% of the locations have advanced more than 100 m. Upward shifts of the tree line were significantly larger in locations heavily modified in the past by anthropogenic disturbance (mean advance 50.8 ± 1.1 m) compared with near natural tree line locations (19.7 ± 0.8 m, P < 0.001), where the mean displacement was much lower than expected and was not related to changes in temperature along the study period. MAIN CONCLUSIONS: Our results stress the impact of the cessation of human activity in driving forest dynamics at the tree line in the Catalan Pyrenees, and reveal a very low or even negligible signal of climate change in the study area.
•Certain coping or incremental adaptation strategies to climate change are not enough, unsustainable, or maladaptive.•Fundamental changes in social-ecological systems that address root causes of ...vulnerability may be needed.•Transformative adaptation characteristics: restructuring, path-shifting, innovative, multiscale, systemwide, and persistent.•Characteristics of transformative adaptation help design strategies to anticipate, guide, or recover from climate change impact.•They can be deliberately included in adaptation plans when appropriate to accommodate desired changes for more sustainable climate change responses.
In the face of major shifts in temperature and precipitation, some conventional strategies that help people to cope or incrementally adapt to climate change may become inappropriate in the long-term. Transformative adaptation, i.e. fundamental systems’ changes that address root causes of vulnerability may be needed. However, we have a limited understanding of what transformative adaptation looks like in social-ecological systems and when it can be implemented. We applied an interdisciplinary perspective to describing social-ecological shifts driven by climate change. We reviewed 80 recent conceptual publications about responses of social, ecological, and social-ecological systems to climate change. Our review suggests that transformative adaptation is characterized as being restructuring, path-shifting, innovative, multiscale, systemwide, and persistent. Despite several barriers to implement transformative adaptation, policy makers and practitioners should consider this option in adaptation plans to help societies to anticipate, guide, or recover from radical climate change impact. Using transformative adaptation to navigate shifts driven by climate change can increase the efficiency and sustainability of climate solutions.
Flash floods cause severe natural disasters over the world generating property and infrastructures damages, poverty and loss of human life, among others. Mediterranean coastal watersheds are ...specially sensible to flash floods effects due to their typical drainage basin features (steep slopes, short concentration times, complex orography, etc.) and the high rainfall intensity typical of convective systems. In the present study, the temporal evolution of the hydrological answer in five Mediterranean (SE Spain) ravine basins with sizes from 10.2 km2 to 200.9 km2 were analysed. A sub-daily SWAT model was used at watershed scale to capture the complex hydrological dynamics. Five land use scenarios corresponding to no-urbanization (baseline), 1990, 2000, 2006 and 2012 were evaluated using GIS-based tools. Additionally, statistical significant differences among the studied scenarios were checked employing the Kruskal-Wallis and post-hoc tests based on Mann-Whitney test with BH correction.
Our results show that flash flood risks have increased in the studied catchments due to changes in land uses, particularly affected by a large urban growth. Observed changes in soil uses have been important since the sixties of the last century, because of a high demographic and touristic pressure and specially the urban area has enhanced considerably during the last 22 years. Currently, some of these catchments present around 70% of their surface occupied by urban land uses with high population density producing curve number surpasses 85 and 90 levels. The hydrological response of the studied basins changed to higher flow rate peaks and shorter concentration times. Some discharges increased significantly from the baseline land use scenario (≈50 m3/s, 190 m3/s, 380 m3/s) to the most urbanised scenario (≈235 m3/s, 385 m3/s, 940 m3/s), respectively. These findings provide to urban planning policy makers very useful information in the face of flash flood effects, which have cost even human lifes in the studied ravine basins during last years.
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•High urban development in the coastline of SE Spain increases curve number rates (80–90).•In Mediterranean convective systems, some precipitation episodes surpass 200–300 mm in 3 or 4 h.•Flash floods simulations, through the SWAT code, reported discharge rates which exceed 900 m3/s.•Peak flow rates have doubled or tripled as a consequence of changes in the land use during last decades.•Improving hydraulic barriers and socio-environmental risk perception against flash floods effects is mandatory.
Ecosystem service value (ESV) refers to the value of benefits provided by the ecosystem to people, and can reflect the quality of regional ecological environment. There have been few studies on ESV ...in arid regions experiencing dramatic land use changes. Also, many past ESV studies have obtained distorted results by using a simple linear function to examine the trade-offs between driving factors. This study quantified ESV in Xinjiang from 1990 to 2020 based on value equivalent method. Differences in ESV among ecosystem services in Xinjiang under different scenarios were simulated using a Bayesian network model. The results demonstrated land use changes in Xinjiang from 1990 to 2020, with construction land expanding the most significantly (dynamic index: 224.63 %), whereas grassland area decreased (dynamic index: −1.31 %) due to transformation to unused and cultivated land. ESV in Xinjiang presented an N-shaped variation trend from 1990 to 2020 and decreased by 309.6 × 108 CNY, with a variation rate of −20.35 %. The rank of the four categories of ecological services from 1990 to 2020 in terms of ESV was: regulating services > support services > cultural services > supply services. There was a gradual reduction in ESV in Xinjiang from 1990 to 2020. The rank of the different regions in terms of the reduction in ESV was: Northern Xinjiang (295.24 × 108 CNY) > Southern Xinjiang (280.94 × 108 CNY) > Eastern Xinjiang (109.76 × 108 CNY). Land use change was a direct driver of changes in ESV, whereas natural and social factors, such as precipitation, temperature, population, and policy factors, were indirect drivers. This study can act as a reference for sustainable management of ecosystem services in arid regions.
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•Land use change as a direct driver of change of ecosystem services value (ESV) in Xinjiang•Degradation of grasslands as the main land use type affecting ESV change in Xinjiang•Quantitative assessment of ESV under different land use changes•Optimal allocation of support services to the Northern Xinjiang should be enhanced.
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