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Birds extend their flight envelope and adapt to time-varying aerodynamic demands by actuating the shoulder and wrist joints to morph the local sweep angles of the inner and outer wings. However, the local sweep morphing may cause unfavourable unsteady lift on the lifting surface. We investigate these unsteady lift responses using an avian-inspired wing with local sweep morphing under different morphing strategies. The unsteady lift is computed through numerically solving the incompressible Navier–Stokes equations. The results show that the local sweep morphing wing experiences a substantial maximum lift overshoot when forward sweeping and a notable maximum lift undershoot when backward sweeping. These lift over/undershoot phenomena can be alleviated by three measures: adopting smooth nonlinear morphing kinematics, initiating morphing from lift extrema opposite to the over/undershoot direction and prolonging the morphing duration. For the lift over/undershoot, the component obtained by subtracting the extended pre-morphing lift is attributed to the modification induced by local sweep morphing. To predict such lift over/undershoot, we develop a reduced-order unsteady model for the sweeping-modification lift coefficient, where Prandtl’s lifting-line theory is extended to the regime of variable translational velocity. The proposed model captures the symmetry of the sweeping-modification lift coefficient, dominated by the horizontal morphing velocity. Additionally, the vertical morphing velocity is found to correlate with the asymmetry of the sweeping-modification lift coefficient by modulating the leading-edge vortices. This study is expected to improve the understanding of surging-wing flow physics and support the design of bio-inspired multifunctional aircraft.
Haiti, 2004; USA, 2005; Myanmar, 2008; Pakistan, 2010; Thailand, 2011; Philippines, 2013; Brazil, 2014; Caribbean, 2017; Tonga, 2018; India, 2018; Mozambique, Zimbabwe, and Malawi, 2019; Australia, 2019–2020; Germany, 2021; Pakistan, 2022; Europe and the United Kingdom (UK), 2022; China, 2022; the United States (US), 2023; Libya, 2023; Kenya and Tanzania, 2024; Brazil, 2024; Poland, 2024; Bangladesh, 2024.
In recent decades, different regions of the world have experienced disasters that are increasingly attributable to the climate crisis (cf. IPCC 2021).1 These disasters, though differing in scale and geographical location, share common characteristics. In all these cases, those affected are at varying degrees of risk, both globally and in the place where the disaster occurred.2 In all of these cases, the slippery slope of vulnerability correlates closely with prior marginalization based on race, gender, class, education, and other factors (cf. Méjean et al 2024; Cappelli, Costantini, and Consoli 2021; Belkhir and Charlemaine 2007; Giroux 2006). These disasters are not only ‘non-natural’ because they occur in the context of anthropogenic climate change, but also because they overlap with politically determined preconditions (cf. Dawson 2010, 317). As the human rights activist and actor Danny Glover graphically illustrated in the aftermath of Hurricane Katrina (cited in Akuno 2006, 34),
When the hurricane struck the Gulf and the floodwaters rose and tore through New Orleans, plunging its remaining population into a carnival of misery, it did not turn the region into a Third World country [sic] – as it has been disparagingly implied in the media – it revealed one. It revealed the disaster within the disaster; gruelling poverty rose to the surface like a bruise to our skin.
The climate crisis demands that we confront the economic models and modes of production that have led us to this precipice of destruction. The concept of climate justice takes into account ‘a variety of interrelated concerns – for the inequitable impact [the climate crisis] has on a range of already vulnerable communities, for participation and procedural justice, for the basic functioning and provision of needs in vulnerable communities, including ecological communities … [for] inclusion, transparency, compensation, and sustainability’ (Schlosberg and Collins 2015).
Applying a climate justice lens therefore requires us to look at the myriad impacts that extractive economic models have on the climate, the environment, and communities’ rights, safety, and wellbeing.
While much of the critique of extractive development has been (appropriately) focused on the extraction of fossil fuels, it is essential to also consider agriculture. In its current extractivist and industrial form, agriculture accounts for an estimated 22 per cent to 23 per cent of global greenhouse gas (GHG) emissions (IPCC 2023, IPCC 2019). Industrial agriculture is also a significant contributor to the interrelated ecological crises of soil depletion, loss of biodiversity, loss of pollination, and destruction of the global water supply (Shiva 2016). Furthermore, as demonstrated in the case studies explored in this chapter, extractivist agriculture has been rooted in cycles of land grabbing and violence against local communities.
As Oxfam (2016) explains, ‘large-scale monoculture investments seek fertile land with good transport connections. In many places, this means displacing peasant, indigenous and Afro-descendant communities, depriving them of their traditional livelihoods.’
For at least two centuries, major development has integrated the island of Borneo into the international market upon which a contested socio-ecological process set forth. Evidence reveals that the increasingly global market, operating through colonial contexts, infiltrated Borneo's economy by exploiting forest products, mineral resources, and essential commodities (Phillips 2016). At issue is the suppression of ‘native’ life by controlling the population, the imposition of economic monopoly, and the exclusion of these resources. This brutal marginalization is still ongoing and marks a colonial legacy, suppressing the rights of indigenous communities.
For example, the current extractivist and modern plantation models have been shown to be racially discriminatory, as evidenced by colonial agrarian policies that have disregarded the rights of indigenous peoples and sought to assert European control over their traditional territories (McCarthy and Camb 2009). The ideas presented in this chapter are informed by my research on indigenous climate justice adaptation in Borneo. As marginalization intersects with other environmental crises occurring at the local level, this chapter focuses on how the spiritual and disenchanted perspectives of the Dayak people remain relevant to ongoing crises and injustices within the context of climate change and the global political–economic system. The United Nations Department of Economic and Social Affairs has indicated that indigenous communities exhibit a minimal level of responsibility for climate change, while simultaneously experiencing the most severe consequences of its associated hazards (United Nations Department of Economic and Social Affairs n.d.).
The United Nations Framework Convention on Climate Change (UNFCCC), signed in 1992, brings together countries in a worldwide commitment to contain global warming. With the Paris Agreement, signed in 2015, this commitment is renewed and takes on an emergency character, challenging the legal field to think of strategies that establish, in the connection of national and international spaces, the duty to act to guarantee the continuity of all forms of life on the planet. The transformations required on an emergency basis to contain the advance of global warming are structural and lead to the need to rethink the entire production process. The context used in this chapter portrays Brazilian rural development in the face of the climate emergency.
In agricultural production, there is a clear contradiction between the emergence of climate change and the continued exploitation of export-oriented monocultures, known as agribusiness. The history of the word ‘agribusiness’ began in the 1940s at the Harvard Business School, with Donald K. Davis and the intention of creating a disciplinary area of studies on agriculture and business, based on liberalism and aimed at reducing the role of the state in regulation and opening up to private initiative (Pompeia 2021, 43–46). The expression appeared in the Brazilian public arena between the 1950s and 1960s (Pompeia 2021, 87). This period was marked by the debate between conservative and progressive forces about development and was interrupted by the military coup of 1964 (Pompeia 2021, 90).
There is a slow, albeit steady, evolution towards the significance and development of economic, social, and cultural rights (ESCRs), moving from international to regional and national systems. Constitutionally elevating ESCRs to fundamental human rights places substantive meaning on the notion of indivisibility and justiciability of all human rights. Climate change poses a threat to this elevated set of human rights, disproportionately impacting the historically marginalized and underserved communities on a global scale. Moreso, progress towards sustainable development for the Global South has been negatively impacted by climate change disasters – severe weather conditions such as droughts and floods have become more frequent and destructive. Consequently, the financing gap and general capacity of the Global North and Global South countries to progressively realize ESCRs is ever widening. It is a major concern that the climate emergency the world is confronted with is a problem to which the Global South has played a minimal role contributing. Rapid industrialization, wealth creation, and improved living standards in the Global North have been spurred by a tainted history of unsustainable natural resource extraction and unsustainable industrial practices much to the detriment of the Global South, which has given rise to the notion of climate justice.
Climate justice is not an exclusively environmental concern but also has implications for the implementation and protection of fundamental civil and political rights, as well as ESCRs. On 28 July 2022, the United Nations General Assembly (UNGA) through resolution A/RES/76/300 confirmed the United Nations Human Rights Council (UNHRC) resolution recognizing for the first time that access to a clean, healthy, and sustainable environment is a human right.
Our methodological approach was based on semi-structured interviews conducted between October 2022 and February 2023. These interviews involved indigenous, Afro-descendant, and Campesinx leaders from academia, labour unions, and social movements. We conducted the interviews in person through video calls, email, and phone. Due to the diversity of the participants, the interviews were performed in Spanish, Portuguese, and English. We had the support of native and bilingual speakers to review the translations1 and shared the final version of the document with the interviewees.
The research highlights the perspectives of several influential voices, including Ana Lucía Ixchiu Hernández, a K’iche’ indigenous social leader and renowned activist for climate and cultural rights in Guatemala; Jen Deerinwater, an award-winning journalist and community organizer from the Cherokee Nation of Oklahoma in the United States (US); Eliana Asprilla, an Afro-descendant environmental engineer specializing in urban and management planning from Colombia; Ana Lilia Felix, an academic who aligns with the Zapatista movement's ‘Sixth Declaration of the Lacandona Jungle’ in Mexico; and Maria Estélia de Araújo and Luciomar Monteiro, members of the Landless Workers’ Movement (MST) and the Catholic Church's Land Pastoral Commission (CPT) in Brazil. For the interviewees’ biographical information and guiding questions, please refer to Appendix 7A in this chapter.
In terms of our selection criteria for interviewees, we employed a non-random sampling approach, specifically purposive sampling. This selection was based on the significant roles that these activists play in the social and environmental justice arenas within both their individual countries and the broader region.
Variational data assimilation and machine-learning based super-resolution are two alternative approaches to state estimation in turbulent flows. The former is an optimisation problem featuring a time series of coarse observations, the latter usually requires a library of high-resolution ‘ground truth’ data. We show that the classic ‘4DVar’ data assimilation algorithm can be used to train neural networks for super-resolution in three-dimensional isotropic turbulence without the need for high-resolution reference data. To do this, we adapt a pseudo-spectral version of the fully differentiable JAX-CFD solver (Kochkov et al., Proc. Natl Acad. Sci. USA, vol. 118, issue 21, 2021, e2101784118) to three-dimensional flows and combine it with a convolutional neural network for super-resolution. As a result, we are able to include entire trajectories in our loss function, which is minimised with gradient-based optimisation to define the neural network weights. We show that the resulting neural networks outperform 4DVar for state estimation at initial time over a wide variety of metrics, though 4DVar leads to more robust predictions towards the end of its assimilation window. We also present a hybrid approach in which the trained neural network output is used to initialise 4DVar. The resulting performance is more than twice as accurate as other state estimation strategies for all times and performs well even beyond known limiting length scales, all without requiring access to high-resolution measurements at any point.
Linkages between environmental risks and racial discrimination have long been areas of research and activism in the domestic sphere. The term ‘environmental racism’, coined by Rev. Dr Benjamin F. Chavis Jr and Robert D. Bullard in the 1980s, refers to racial discrimination embedded into the process of environmental decision-making, whether by a conscious design or institutional neglect (Bullard 1993, 17). The results are that communities of colour are disproportionately exposed to environmental issues (Bullard 1990, 1993; Schlosberg and Collins 2014). However, an unresolved theoretical issue in this conversation is applying such framework in the global order, particularly considering Global South countries1 in the realm of international negotiations on climate change. Such an application builds on scientific evidence that communities most at risk have emitted the least greenhouse gases (GHGs) and also have fewer resources to deal with climate change, and that climate change has generated and perpetuated vulnerabilities (IPCC 2022, 9–11). This is deeply intertwined with the principle of common but differentiated responsibilities and respective capabilities (CBDR&RC principle), since it acknowledges that Global North countries should bear the higher costs of mitigation and adaptation to climate change, as well as recent discussions on climate justice and human rights – particularly considering the economic, social, and cultural (ESC) rights. However, the current understanding and operationalization of the CBDR&RC principle does not enhance climate justice and human rights, because it does not address the underlying root causes of climate change (see the third section).
Spatial linear instability analysis is employed to investigate the instability of a viscoelastic liquid jet in a co-flowing gas stream. The theoretical model incorporates a non-uniform axial base profile represented by a hyperbolic tangent, capturing the shear layer. The Oldroyd-B model discretised with Chebyshev polynomials is employed, and energy budget analysis is used to interpret underlying mechanisms. At low Weber numbers, the jet evolves axisymmetrically and the instability is governed by interfacial gas-pressure fluctuations; as the Weber number increases, the growing inertia drives a transition of the predominant mode from axisymmetric to helical. At weak elasticity, the instability is also primarily governed by gas-pressure fluctuations. As elasticity increases, the predominant mode transitions from axisymmetric to helical. This transition is accompanied by a migration of disturbance structures from the interface toward the jet interior and an enhanced coupling between velocity perturbation and the basic flow. These trends reveal a new predominant instability mechanism – the elasticity-enhanced shear-driven instability – which is distinct from capillary or Kelvin–Helmholtz instabilities in Newtonian jets. A $\textit{We}$–$El$ phase diagram delineates the boundary between predominant modes and experimental results obtained in a flow-focusing configuration validate the theoretical predictions. Compared with temporal stability results, the spatial framework – by directly resolving the convective downstream amplification of disturbances – achieves quantitative agreement with experiments and highlights the superiority of spatial instability analysis in capturing the dynamics of strongly convective, non-parallel jet flows. These findings provide mechanistic insight into viscoelastic jet instabilities and offer guidance for applications involving droplet and fibre formation in co-flow systems.
According to estimates made by the Intergovernmental Panel on Climate Change (IPCC) in 2019, the global agro-food system's emissions account for about 21 per cent to 37 per cent of total anthropogenic greenhouse gas (GHG) emissions (IPCC 2022a). Almost half of those emissions can be attributed to deforestation and land use changes associated mainly with the growth of the agricultural and livestock borders (Ecologistas en Acción n.d.). In this context, the production of soy for animal feed and biofuel represents a major contributor to the carbon footprint (Ecologistas en Acción n.d.). An estimate of 85 per cent of the worldwide soy production is used to feed animals (Ritchie and Roser 2021; WWF 2007).
The prevalent agribusiness model in the Latin American Southern Cone is characterized by the large-scale cultivation of genetically modified (GM) seeds, mainly of soy, which have been developed to tolerate primarily glyphosate, among other herbicides. Moreover, this model entails high levels of land concentration and monocultures and is one in which few large transnational corporations have high levels of market share for the production and distribution of both GM soy seeds and glyphosate. The other end of the value chain mirrors this scenario, with only a few retail companies dominating the market.
Since its introduction to the market in the 1990s, GM soy seeds and associated pesticide use have become one of the major drivers behind the decline of South America's natural ecosystems, especially in the tropics (Fehlenberg et al. 2017). The use of both products together has increased substantially over the years as weeds have evolved to become resistant to glyphosate (Perry et al. 2016; Tsatsakis et al. 2017).
Camassa et al. (J. Fluid Mech. 745, 2014, 682–715) demonstrated excellent agreement between the theoretical predictions using the longwave equation and experimental observations for the absolute instability-induced plug formation in the gravity-driven flow of a liquid coating the inner surface of a tube. A similar flow of airway surface liquid (ASL) exists in the proximal airways, driven by the turbulent airflow in addition to gravity. Motivated by the conclusions of previous studies, we probe for the existence of absolute instability in the proximal airways in the present study to determine plug formation and subsequent airway closure by considering ASL elasticity, cylindrical flow geometry and the effect of inhaled air temperature. To accomplish this, we derive a longwave evolution equation, which is then used to obtain the dispersion relation. In contradistinction to the distal airways, the analysis predicts the absence of absolute instability-induced airway closure in the proximal airways for a healthy lung. However, an increased ASL thickness and/or elasticity due to excessive secretion of mucus and mucins in a diseased lung could lead to airway closure due to ASL plugs. Furthermore, inhaling colder air (than body temperature) enhances the absolute instability region, and the opposite is true for inhaling warmer air (than body temperature). For lungs with increased ASL thickness (due to diseases), plug formation is aggravated by colder air inhalation, thus demonstrating that inhaling colder (warmer) air is detrimental (beneficial) for diseased lungs. The predictions of the present analysis are in agreement with clinical observations.
Ascidiella aspersa is a solitary ascidian native to the North-east Atlantic that has been introduced to many regions around the globe. In 2023, individuals matching the description of A. aspersa were found on an artificial dock structure in Stanley Harbour, Falkland Islands, where there were no previous records of the species. Individuals were collected for morphological and genetic analyses, and previous surveys of the site were reanalysed to estimate the abundance of the population. The morphological examination and genetic analysis confirmed the individuals were A. aspersa. Analysis of the survey data suggested the species has been present since at least 2011 and forms a reasonably dense population on the more sheltered areas of the dock structure. Further survey work and population genetic investigations are required to better understand the likely origin of the population, and the abundance and extent of the species around the Falkland Islands.