Falling Lake Victoria water levels: Is climate a contributing factor?

Recently, and perhaps most threatening, Lake Victoria water level has been receding at an alarming rate. A recent study suggested the possibility of the expanded hydroelectric power station in Uganda. However, since the lake receives 80% of its refill through direct rainfall and only 20% from the basin discharge, climatic contributions cannot be ignored, since the 80% water is directly dependant on it. It is therefore necessary to investigate climatic contribution to the declining Lake Victoria water level observed over a long period, i.e., 30 years. This contribution uses 30 years period anomalies for rainfall, river discharge and lake level changes of stations within Lake Victoria basin to analyse linear and cyclic trends of climate indicators in relation to Lake levels. Linear trend analysis using the Student’s t test indicate a decreasing pattern in rainfall anomalies, with the slope being statistically similar to those of water levels at both Kisumu, Maziba and Jinja stations for the same period of time (1976–1999), thus showing a strong correlation. On the other hand, cyclic trend analysis using Discrete Fourier Transform (DFT) shows cyclic period of water level to coincide with those of droughts and rainfall. The strong relationship between climatic indicators of drought and rainfall on one-hand and lake levels on the other hand signifies the need to incorporate climate information in predicting, monitoring and managing lake level changes.     

Coal taxes as supply-side climate policy: a rationale for major exporters?

The shift away from coal is at the heart of the global low-carbon transition. Can governments of coal-producing countries help facilitate this transition and benefit from it? This paper analyses the case for coal taxes as supply-side climate policy implemented by large coal exporting countries. Coal taxes can reduce global carbon dioxide emissions and benefit coal-rich countries through improved terms-of-trade and tax revenue. We employ a multi-period equilibrium model of the international steam coal market to study a tax on steam coal levied by Australia alone, by a coalition of major exporting countries, by all exporters, and by all producers. A unilateral export tax has little impact on global emissions and global coal prices as other countries compensate for reduced export volumes from the taxing country. By contrast, a tax jointly levied by a coalition of major coal exporters would significantly reduce global emissions from steam coal and leave them with a net sector level welfare gain, approximated by the sum of producer surplus, consumer surplus, and tax revenue. Production taxes consistently yield higher tax revenues and have greater effects on global coal consumption with smaller rates of carbon leakages. Questions remain whether coal taxes by major suppliers would be politically feasible, even if they could yield economic benefits.     

Mulching as a means of exploiting dew for arid agriculture?

A traditional mulching technique used in Lanzarote, Canary Islands, allows dry farming as well as pronounced water savings in irrigation. It is known to reduce evaporational losses, but is also supposed to enhance the nocturnal condensation of water vapour from the atmosphere. The mulch layer consists of porous volcanic rock fragments abundantly available on the island. The mulched surface is believed to cool rapidly and to be more hygroscopic than a bare soil surface. This was investigated during a field experiment conducted over 68 nights during different seasons in 2001 and 2002, as well as some simple laboratory measurements. It was found that nocturnal condensation on the mulch surface (max 0.33 mm) was lower than on the bare soil surface (max 0.57 mm) or any one of three alternative mulch substrates. However, a slightly stronger nocturnal cooling of the mulched as compared to the bare surface was present. It is shown that these contrary findings can be explained by the higher hygroscopicity of the dry loam soil, resulting in condensation gains beyond the strict definition of dew. Differences in plant-availability of non-hygroscopic dew water and hygroscopic water uptakes are discussed, and conditions under which mulching would show positive condensation effects are defined. This includes a theoretical section demonstrating that non-hygroscopic mulch layers of a proper thickness can provide small amounts of dew to plant roots at the mulch–soil interface. This condensation could also happen during the day and would be favoured by a high amplitude of the diurnal atmospheric moisture cycle.     

Managing urban water systems with significant adaptation deficits—unified framework for secondary cities: part II—the practice

Adaptation gaps are shortcomings of a system responding to climate change, whereas adaptation deficits are shortcomings in providing services. These two drivers for adaptation are often in conflict in many secondary cities in the global south (SCGS). It is possible to align these seemingly conflicting drivers into a productive unity, a conceptual alignment, which is the first step in achieving harmony while implementing adaptation actions. This paper focuses on the practical aspects of implementing aligned adaptation action that leads to improvements in liveability, sustainability, and resilience of SCGS. At an abstract level, the nature of the adaptation problem is similar to the complex problems identified in various domains, such as software development, manufacturing, and supply chain management. The widely accepted “agile principles”—used in the above domains—is the basis for developing a set of twelve principles for urban adaptation, which are synthesized from numerous recent studies that have implicitly proposed or applied most of these principles to climate change adaptation in urban settings. These principles lead to four essential objectives appertaining to the process of sustainable urban adaptation. The urban agile principles are used to analyze the current state of adaptation of Can Tho City in Vietnam and to ascertain the agile ways of addressing its adaptation challenges. Analysis of the outcomes shows that harmonized approaches can simultaneously address both adaptation deficits and gaps.     

Climate change and the incidence of a forest pest in Mediterranean ecosystems: can the North Atlantic Oscillation be used as a predictor?

Many forest pest species strongly depend on temperature in their population dynamics, so that rising temperatures worldwide as a consequence of climatic change are leading to increased frequencies and intensities of insect-pest outbreaks. In the Mediterranean area, the climatic conditions are strongly linked to the effects of the North Atlantic Oscillation (NAO). The aim of this work is to analyze the dynamics of the pine processionary moth (Thaumetopoea pityocampa), a severe pest of Pinus species in the Circunmediterranean, throughout a region of southern Spain, in relation to NAO indices. We related the percentage of forest plots with high defoliation by pine processionary moth each year with NAO values for the present and the three previous winters, using generalized linear models with a binomial error distribution. The time series is 16-year long, and we performed analyses for the whole database and for the five main pine species separately. We found a consistent relationship between the response variable and the NAO index. The relationship is stronger with pine species living at medium-high altitudes, such as Aleppo (P. halepensis), black (P. nigra), and Scots (Pinus sylvestris) pine, which show the higher defoliation intensities up to 3?years after a negative NAO phase. The results highlight, for the first time, the usefulness of using global drivers in order to understand the dynamics of pest outbreaks at a regional scale, and they open the window to the development of NAO-based predictive models as an early-warning signal of severe pest outbreaks.     

Why were some La Niñas followed by another La Niña?

This paper investigates why some La Niña events are followed by another La Niña and some others are not. We propose two preconditions that result in continuation of a La Niña. The first one is that La Niña must be a strong event (a major La Niña). This ensures that the reflected Rossby wave signal at the eastern boundary of the Pacific has a strong westward propagating cold ocean temperature anomaly over the off-equatorial region. The off-equator cold anomaly may not be conducive to the equatorial recharge process, and as a result, may favor the persistence of cold ocean subsurface temperature anomaly and prevent the transition from La Niña to El Niño. The second precondition is whether there are eastward propagating downwelling Kelvin waves during the decay phase of a major La Niña. Eastward propagating downwelling Kelvin waves could lead to demise for a tendency for a follow-up La Niña. The equatorial Kelvin wave activities are associated with fluctuations of surface wind in the equatorial far-western Pacific. The analysis suggests that both the surface wind in the equatorial far-western Pacific and the recharge/discharge of the equatorial Pacific are indicators for occurrence or no occurrence of a follow-up La Niña event.     

Mid-Century Strategies: pathways to a low-carbon future?

Since the Paris Agreement was adopted in 2015, both national and subnational governments have been encouraged to submit Mid-Century Strategies, outlining how they would reach their deep decarbonization goals. However, research on the design and potential of these strategies has been very limited. To address this shortcoming, here we assess 13 such strategies – six national, seven subnational – in a comparative fashion. We find that the energy-economy-climate models underpinning these strategies are generally of high quality, though national jurisdictions generally performed better. However, most strategies are not plausible without significant changes to policy, and the industrial sector in particular presents a major limitation. The strategies are helpful in revealing this gap, but much works remains to be done for plausible mid-century decarbonization trajectories to become a reality. We also find that public input and societal participation in strategy building were a double-edged sword depending on the constellation of domestic preferences.

• Governmental Mid-Century Strategies for deep decarbonization are underpinned by high-quality energy-economy-climate models

• Governments’ proposed strategies require significant new policies, as even among jurisdictions that have an MCS, extant policies are insufficient to achieve deep decarbonization

• No jurisdiction studied has yet put forward a plausible decarbonization policy for the industrial sector.

• Public input and societal participation can be a double-edged sword: they can increase durability of the strategy but also enable opposing forces to mobilize against ambitious changes.

     

Land-based adaptation to global change: What drives soil and water conservation in western Africa?

Conservation of land resources is a promising strategy for sustainable agricultural intensification in order to adapt dryland farming systems to climate, market and other stresses. At a local level, factors that drive the adoption of conservation measures operate and interact in specific ways. Linking our knowledge of the local specifications of these drivers to regional and global patterns of vulnerability can significantly enhance our understanding of land-based adaptation to global change. However, the factors that influence the adoption of conservation practices remain actively debated. Therefore, this study presents a meta-analysis of case studies that investigate the adoption of soil and water conservation measures, as an important approach to resource conservation. Synthesising 63 adoption cases in the drylands of western Africa, this meta-analysis reveals a multitude of factors that drive the adoption of soil and water conservation practices. The drivers differ strongly between particular practices and methods of analysis used in the case studies. Contributing to the broader debate on resource conservation, the findings highlight the adoption of soil and water conservation measures as an emergent property of farming systems. They demonstrate the need to better understand the socio-ecological foundation of adoption and the pathways along which adoption evolves in space and time. This study concludes with methodological principles to advance future research on the factors that drive the adoption of soil and water conservation measures as a pre-requisite of improving land-based adaptation efforts.     

Selling climate change? The limitations of social marketing as a strategy for climate change public engagement

Social marketing is the systematic application of marketing concepts and techniques to achieve specific behavioural goals relevant to the social good. Social marketing approaches are becoming increasingly popular among governmental and non-governmental actors seeking to engage the public on climate change. The effectiveness of social marketing in achieving specific behavioural goals is empirically well-supported. However, in the first systematic critique of social marketing as a strategy for engaging the public on climate change, we present evidence that social marketing alone is insufficient to build support for the more ambitious policy changes and interventions that constitute a proportional response to climate change. In some circumstances, social marketing approaches may even be counterproductive. We describe some alternative approaches for engaging the public, which may provide governmental and non-governmental actors with additional or preferable tools for promoting public engagement with climate change. Given the scale of the challenge, it seems critical that those seeking to engage the public are equipped with the most effective strategies available - a goal that this paper seeks to contribute to. We conclude that acknowledging the limitations of social marketing - and exploring alternative methods of engaging the public - is an urgent task for climate change communication researchers and practitioners.     

The tornado over Khanty-Mansiysk: An exception or a symptom?

Analyzed are large- and mesoscale atmospheric processes which preceded and accompanied the tornado formation on June 12, 2012 near Khanty-Mansiysk city (61° N) in West Siberia. After the record-breaking hot weather observed in the region during the first half of June 2012, the tornado formation was favored by the passage of the cold front (cold advection at low altitudes), by the wind rotation with height in the lower atmospheric layer of 1.5 km (by more than 180°), and by very high air humidity in the surface layer with the cloud base of about 200 m. Estimated are the possible trends in the nature of the atmospheric circulation over West Siberia at the global warming observed in the 21st century which may contribute to a more regular tornado formation in high-latitudinal regions due to the physiographic peculiarities of the region.     

Policy integration: Do laws or actors integrate issues relevant to flood risk management in Switzerland?

Existing research emphasizes interdependencies between social and ecological systems in climate change adaptation. Ecological systems are often complex and span several issues that are not integrated in the social governance system. In order to increase the fit between social and ecological systems, understanding factors that promote the integration of interdependent issues is crucial. In this paper, we consider 11 issues related to flood risk management, e.g., technical flood protection and habitat loss, which are typically addressed in different policy sectors but exhibit ecological, functional, or geographical interdependencies. We analyze two bases for issue integration: a) political actors connecting issues and, b) the legal framework cross-referencing issues. We propose a network method for systematic comparisons between issue integration based on actors and integration based on laws. For the case of Swiss flood risk management, we find that actor- and law-based issue integration co-vary and might be self-reinforcing. We further find that issue integration mostly rests on laws, although cases exist where actors are the main basis of integration. Results promote our understanding of potential bases for the integration of policy issues, thereby contributing knowledge about adaptive governance capacities in social-ecological systems that buffer the effects of climate change.     

Altitude profile of the OH radical complex with water in Earth’s atmosphere: a quantum mechanical approach

The hydroxyl radical (OH) is important in both tropospheric and stratospheric chemical processes that occur in Earth’s atmosphere. The OH radical can also strongly hydrogen-bond to form complexes with other atmospheric constituents, like water molecules. Consequently, there is potential for altered reaction dynamics/kinetics as a result of this complexation. Without direct measurements of the abundances of such complexes in Earth’s atmosphere, we have adopted a theoretical approach to determine such abundances. Electronic structures, enthalpies and free Gibbs energies of formation of OH, H₂O and H₂O-HO were calculated at CCSD(T) and QCISD(T) levels of theory with either 6–311++G(2d,2p) or aug-cc-pVTZ basis. Statistical thermodynamic concepts were then used to assess the abundance of the complex as function of altitude.     

Water and energy exchange above a mixed European Beech – Norway Spruce forest canopy: a comparison of eddy covariance against soil water depletion measurement

Summary Evapotranspiration of a mixed European beech – Norway spruce forest was measured by means of the eddy covariance technique during a 19 day fine weather period in August 2000. Site conditions were non-ideal as to conventional micrometeorological standards. Sloping terrain and heterogeneously composed, small fetch required a thorough evaluation of the results by (1) the degree of energy balance closure (EBC), (2) footprint analysis and (3) cross-checking against soil water depletion estimates of evapotranspiration. Spatially distributed soil moisture measurements (194 permanent measuring points across a 70×70m plot) guaranteed extended representativeness of the soil water budget method. Due to the convectively active atmosphere during the observation period and to the low measuring height, the source area of the latent heat flux remained small. Footprint analysis revealed that in 95% of the situations with positive net radiation the cumulative latent heat flux reached 50% of the total flux at a maximum upwind distance of 135 (±27) m. Fifty five percent of the peak footprints occurred within the soil moisture measuring plot, providing good spatial comparability between the two methods for determining evapotranspiration. They differed only by 0.2mm for the whole period, showing better agreement in the second half of the period, when water redistribution in the subsoil had ceased. EBC evaluated on a daily basis ranged between 73 and 92%. No clear relation between magnitude of the closure gap and meteorological parameters could be identified. Overall, 46% of the incident net radiation drove evapotranspiration and 28% were released as sensible heat, the Bowen ratio being sensitive to weather conditions and wind direction, though. The results of this study give confidence that the eddy covariance technique is a useful tool to measure forest evapotranspiration also in complex terrain.     

Physical and chemical impacts of a major storm on a temperate lake: a taste of things to come?

Extreme weather can have a substantial influence on lakes and is expected to become more frequent with climate change. We explored the influence of one particular extreme event, Storm Ophelia, on the physical and chemical environment of England’s largest lake, Windermere. We found that the substantial influence of Ophelia on meteorological conditions at Windermere, in particular wind speed, resulted in a 25-fold increase (relative to the study-period average) in the wind energy flux at the lake-air interface. Following Ophelia, there was a short-lived mixing event in which the Schmidt stability decreased by over 100 Jm^?2 and the thermocline deepened by over 10 m during a 12-h period. As a result of changes to the strength of stratification, Ophelia also changed the internal seiche regime of Windermere with the dominant seiche period increasing from ~?17 h pre-storm to ~?21 h post-storm. Following Ophelia, there was an upwelling of cold and low-oxygenated waters at the southern-end of the lake. This had a substantial influence on the main outflow of Windermere, the River Leven, where dissolved oxygen concentrations decreased by ~?48%, from 9.3 to 4.8 mg L^?1, while at the mid-lake monitoring station in Windermere, it decreased by only ~?3%. This study illustrates that the response of a lake to extreme weather can cause important effects downstream, the influence of which may not be evident at the lake surface. To understand the impact of future extreme events fully, the whole lake and downstream-river system need to be studied together.     

Exploring some of the myths of land use change: Can rural to urban migration drive declines in biodiversity?

Forest transition theory describes a reversal in land-use trends for a given area, from a period of net forest area loss, to a period of net forest area gain. Some assume that such forest gain necessarily equates with biodiversity conservation. We question this assumption, based on research conducted in Oaxaca, Mexico. In Oaxaca's northern highlands, low intensity forest use and rotational (milpa) agriculture have led to pronounced spatial heterogeneity in forest structure and composition, and created a high-biodiversity forest-agriculture mosaic. In the Zapotec community of San Juan Evangelista Analco and the Chinantec community of Santiago Comaltepec, as across much of Oaxaca, fewer people are farming; farmers are cultivating less land, working closer to settlements, and growing fewer crop varieties. Widespread agricultural abandonment has initiated unprecedented changes in ecological succession, patch size, and edge effects, which we speculate will be having an impact on the biodiversity of the landscape mosaic. Our work suggests that the decline of land use activity may result in a gradual loss of the forest-agriculture mosaic, leading to localised declines in biodiversity, despite (or because of) extensive forest resurgence. These findings support the view that indigenous cultures in Oaxaca and Mexico should not be seen as an environmental constraint but rather as an agent of landscape renewal that allows for both cultural and biological diversity to flourish, a reality that national and international conservation bodies need to more fully recognise and incorporate into policy.