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We utilize a variety of climate datasets to examine impacts of two mechanisms on precipitation in the Greater Horn of Africa (GHA) during northern-hemisphere summer. First, surface-pressure gradients draw moist air toward the GHA from the tropical Atlantic Ocean and Congo Basin. Variability of the strength of these gradients strongly influences GHA precipitation totals and accounts for important phenomena such as the 1960s–1980s rainfall decline and devastating 1984 drought. Following the 1980s, precipitation variability became increasingly influenced by the southern tropical Indian Ocean (STIO) region. Within this region, increases in sea-surface temperature, evaporation, and precipitation are linked with increased exports of dry mid-tropospheric air from the STIO region toward the GHA. Convergence of dry air above the GHA reduces local convection and precipitation. It also produces a clockwise circulation response near the ground that reduces moisture transports from the Congo Basin. Because precipitation originating in the Congo Basin has a unique isotopic signature, records of moisture transports from the Congo Basin may be preserved in the isotopic composition of annual tree rings in the Ethiopian Highlands. A negative trend in tree-ring oxygen-18 during the past half century suggests a decline in the proportion of precipitation originating from the Congo Basin. This trend may not be part of a natural cycle that will soon rebound because climate models characterize Indian Ocean warming as a principal signature of greenhouse-gas induced climate change. We therefore expect surface warming in the STIO region to continue to negatively impact GHA precipitation during northern-hemisphere summer.

Abstract In some shelf sea regions of the world, the tidal range is sufficient to convert the potential energy of the tides into electricity via tidal range power plants. As an island continent, Australia is one such region – a previous study estimated that Australia hosts up to 30% of the world’s resource. Here, we make use of a gridded tidal dataset (TPXO9) to characterize the tidal range resource of Australia. We examine the theoretical resource, and we also investigate the technical resource through 0D modelling with tidal range power plant operation. We find that the tidal range resource of Australia is 2004 TWh/yr, or about 22% of the global resource. This exceeds Australia’s total energy consumption for 2018/2019 (1721 TWh/yr), suggesting tidal range energy has the potential to make a substantial contribution to Australia’s electricity generation (265 TWh/yr in 2018/2019). Due to local resonance, the resource is concentrated in the sparsely populated Kimberley region of Western Australia. However, the tidal range resource in this region presents a renewable energy export opportunity, connecting to markets in southeast Asia. Combining the electricity from two complementary sites, with some degree of optimization tidal range schemes in this region can produce electricity for 45% of the year.

Abstract This paper investigates the hydrodynamics of a seabed-mounted, bottom-hinged, flap-type wave energy converter in shallow water. A conceptual model of the hydrodynamics of the device has been formulated and shows that, as the motion of the flap is highly constrained, the magnitude of the wave force on the flap is the key determinant of power capture. The results from a physical modelling program have been used in conjunction with numerical data from WAMIT to validate the conceptual model. The work finds that designing the device to increase the wave force is more profitable than designing it to be tuned to the incident wave climate. As wave force is the primary driver of device performance it is shown that the flap should fill the water column and pierce the water surface to reduce decoupling due to wave overtopping. It is concluded that, in order to maximize capture factor at a typical North Atlantic site, the flap should be approximately 20–30 m wide, with large diameter rounded side edges, having its pivot close to the seabed and its top edge piercing the water surface.

Biodiversity analysis underlies macroevolutionary studies and allows to identify mass extinctions. Numerous studies of mass extinctions show that geological factors play a central role in determining the diversity dynamics. The late Cretaceous extinction is of interest to science as the closest to us extinction of the five mass extinctions that occurred in the Phanerozoic. There is currently no scientific consensus on the scenario in which the extinction occurred on land. In order to assess the features of superorderDinosauriadevelopment during the Cretaceous-Paleogene, the authors have analysed the diversity of terrestrial taxa of Mesozoic dinosaurs. Based on data from the paleobiodb paleontological database using the Python programming language and its libraries, the features of the species diversity ofDinosauriahave been studied. An attempt was made to quantify the species diversity of this group based on the ratio of predators to herbivores using data on dinosaur food types. The simulated diversity data were compared with observed patterns and existing estimates. It is likely that less than one-third of the dinosaurs that existed are currently known, as indicated by the geography of the fossils, and the proportions of dinosaurs by type of diet.

Abstract The Ria de Muros is a large coastal embayment on the north-western coast of Spain in which the peak tidal currents exceed 2 m/s. It is therefore a promising site for tidal stream power. The key point when assessing this resource is the accurate estimation of the tidal currents. In this work a finite difference numerical model is used for this purpose. The model solves the vertically integrated Navier–Stokes hydrodynamics and transport equations. It is validated with in situ velocity measurements performed by means of an acoustic Doppler current profiler (ADCP). Thereafter the tidal flow velocities and the corresponding power densities are computed. The largest values are found in a section of the inner ria, in which two points are selected for a detailed assessment of the resource. The model is then run to compute the tidal stream and the corresponding power density at these points during a 14-day period, so as to cover the spring–neap cycle. The power density curve thus obtained is numerically integrated to compute the annual energy output that can be obtained by a tidal stream power plant at each location.

The offshore wind industry is expanding rapidly around the world due to several factors enabling this source of renewable energy. Stronger wind resources in offshore areas, lack of social and geographical constraints related to onshore wind power, the evolution of technology, and increasing demand for electricity in coastal regions as a result of a massive increase in population are some of the factors favoring the use of wind energy. The assessment of the potential global capacity that considers the different economic, environmental, and social factors and the dynamics of market, policy, and technology are vital for estimating the competitiveness of offshore wind energy in the future energy profile. There are several studies and technical reports that evaluate the potential of offshore wind energy in different countries or regions. They used a different source of data, metrics, and quantitative approaches in appraising the potential offshore wind power capacity and its cost efficiency. The critical factors that have been considered are geographical, technical, economic, environmental, and social and market elements. This paper provides a systematic review for analyzing the studies that address the potential offshore wind energy around the world and published during the 2000–2016 period. This study highlights the key criteria for assessing the potential for offshore wind energy deployment and the related tools and methods.

Abstract Climate change exacerbates existing threats and risks and generates new ones in the lives of the Indigenous people of the Arctic regions. The ability to cope with climate variability and extreme events is largely dependent on territorial adaptive capacities and vulnerabilities in addition to the level of regional economic development. The purpose of this article is to understand if the people living in Tiksi and its hinterland are aware of the impacts of climate change and attribute importance to them, as well as to determine if they have adaptation actions and strategies have been put in place. The future of Tiksi's population is uncertain and is highly dependent on the federal government. Issues relating to climate change are not a high priority for the local populations. Although the population of the Bulunsky district has maintained some capacity for adaptation, both uncertainty about the future and their dependence on decisions made at a higher level are undermining their ability to plan for adaptation in the long term.

The known or suspected presence of offshore hydrocarbons not only has prompted coastal states to elaborate expansive claims of maritime jurisdiction but it has also been influential in the efforts of some states to preclude one another from carrying out economic activities, such as oil exploration and exploitation, in the areas of overlapping claims. In the absence of clear and defined boundaries, possible state responses can range from protracted negotiations to unilaterally undertaken activities, verbal protests and even the threat or use of force. However, one must not view offshore natural resources merely as a source of interstate friction but also as an opportunity to establish strategic alliances over economic and security matters. Joint development has proved to be a pragmatic reflection of this opportunity: it enables the peaceful and coordinated economic utilisation of disputed maritime areas while removing, even temporarily, the disruptive element of contested jurisdiction from the disputing states’ agendas. This paper examines the concept of joint development of offshore oil and gas resources. It discusses the key elements that distinguish joint development from other concepts such as cross-border unitization and outlines the reasons that make joint development practically appealing both in terms of promoting interstate cooperation over seabed activities but also in terms of stimulating energy investments in disputed maritime areas. Additionally, the paper discusses the legal foundations of joint development under the United Nations Convention on the Law of the Sea (UNCLOS) and examines whether states are under a legal obligation to enter into joint development agreements, pending the settlement of their maritime boundaries. Finally, the paper considers the different operative models in which joint development schemes can be structured and implemented having regard to successful or unsuccessful precedents in state practice.