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Climate change has been widely recognised as one of the most urgent and growing threats to natural and cultural heritage in the twenty-first century, and the indelible impact of humanity has led to the definition of a new geological epoch, the Anthropocene. Indigenous peoples are disproportionately affected by natural and human-induced changes to the environment. Their vulnerability is exacerbated by centuries of cultural and territorial disenfranchisement within settler-colonial nations. This dissertation aims at understanding Indigenous perceptions of heritage in the face of climate change and its intersection with the impacts of settler- colonialism. It analyses how these on-the-ground perceptions can, in turn, inform heritage organisations and contribute to safeguarding the many facets of tangible and intangible Indigenous heritage for future generations in the Anthropocene. This is accomplished through a comparative, transnational case study of two communities each from the Dehcho First Nations in the Northwest Territories, Canada, and the Aymara and Quechua peoples in northern Chile. I use a multi-method approach consisting of semi-structured interviews, oral histories and participant observation. The data is complemented by environmental and heritage legislation and grey literature at multiple organisational scales for both case studies. Three lines of enquiry are explored through an applied comparative thematic analysis: i) the perceptions of climate change and associated land loss/change among Indigenous groups and how this impacts each group’s notions of challenges to its cultural identity; ii) the intersection of the effects of post- colonialism, ongoing industrial activities and climate change on the intergenerational transmission of ancestral knowledge and notions of place attachment; and iii) how international, national and regional political and sociocultural rhetoric on environmental and heritage conservation affect local, grassroots considerations for safeguarding heritage. The similarities and contrasts of the Dehcho First Nations, Aymara and Quechua experiences of climate change across the North-South divide are related from the grassroots to arrive at redefining heritage practices in the Anthropocene. The results demonstrate that decolonising heritage is not only necessary, but that this decolonisation depends on building and actively engaging in intercultural empathy through the global threat of climate change. In order to understand how Indigenous practices, places, and items are valorised—attributed value—as heritage in the face of climate change, one must empathise with the cultural loss that exists in the temporal and cognitive spaces between Indigenous individuals’ moments of nostalgic reference and today.

Achievement of sustainable development in light of ongoing climate change and biodiversity pressures benefits from the deployment of innovations that foster engagement and uptake across all levels, mobilises finance flows commencement to the scale of the challenge, and enables the dissemination of transition solutions that support the low carbon economy. This research investigates the relationship between the legal architecture of market mechanisms under international law and the role of private actors, and how this contributes to sustainable development. Through an exploration of how market mechanisms under the climate change and biodiversity regimes have achieved environmentally sound outcomes, been advanced in sectoral approaches, and facilitated via bilateral and multilateral trade and investment relationships, important insights are identified regarding the composition of effective law and governance architectural approaches. Leveraging experiences derived from treaty practice viewed through an interactional account of international law, this assessment elucidates the important role played by alignment of legal regimes, robust transparency measures, and complementary schemes such as stakeholder-endorsed certifications in buttressing the established measures to ensure sustainable development outcomes and contributes to understanding the role of private actors in the operationalisation of environmental agreements. Research findings suggest it is the interaction of norms across the international legal architecture, informed by relationships within and across relevant treaty systems and the general corpus of international law, and actualised through engagement with private actors as a component of market mechanisms that provides the opportunity for congruence of practice, forging of shared understandings, and normative internalisation and ownership among communities of practice that stimulates both innovative solutions and ambitious action.

Over the past several years, online disinformation and misinformation concerning climate change have gained substantive attention within the scientific community. However, while the dynamics that drive the circulation of false online information have been analysed extensively, it remains unclear whether (and how) this phenomenon can be counteracted. This research project analyses the emerging role of bottom-up mobilisations as a form of noise-reduction, thereby examining how social movements may deploy peer-produced communication narra- tives to counteract the circulation of online disinformation and misinformation relating to climate change. To investigate this communication dynamic, this research applies techniques from computational social sciences to an original dataset of ≈ 250k Facebook posts produced by two movements that best embody this novel and innovative generation of radical envi- ronmental activism: Extinction Rebellion and Fridays for Future. The central thesis of this project forwards two original contributions to the fields of climate change communication and social movement studies. First, it analyses the emergence of a new generation of radical climate change movements and the significance of this new development in climate activism (Chapter II). Second, it offers interdisciplinary empirical evidence on how radical climate movements can act as a bottom-up force for what I term ‘epistemic activism’. It presents a theoretical framework where activist-led, peer-produced communication can provide a coun- tering force to both vertical disinformation and horizontal misinformation. It quantitatively analyses two channels through which these forms of false information can be opposed. For reducing vertical disinformation, this work assesses the use of naming and shaming against information polluters (Chapter III), while for horizontal misinformation, it evaluates the dissemination of scientific counter-narratives (Chapter IV). Ultimately, this thesis shows that the two movements under analysis engage extensively in epistemic activism, with great potential to influence the online climate change debate positively.

Ammonia has been responsible for feeding population growth in the 20th century through synthetic fertilizer, and is poised to become the preferred energy storage medium for a society powered by renewable electricity in the 21st century. However, conventional brown ammonia production through the Haber-Bosch process is optimized for utilization of centralized and steady energy supply from fossil-fuels. When shifting to distributed and intermittent energy supply through wind and solar energy, a re-optimization is required for a low-capital and flexible green ammonia production processes. This thesis re-designs and Haber-Bosch process by targeting the integration of reaction and separation in a single process vessel at low pressures, thereby achieving the simplification and down-scaling of the high pressure recycle loop of the Haber-Bosch process. Materials are developed for this purpose, the feasibility of integration is demonstrated, and mathematical modeling is utilized for assessing the application of the single-vessel process to a range of renewable energy sources in comparison to competing ammonia production processes. Herein, a catalyst with low-temperature (< 350°C) and high-conversion (i.e. near equilibrium) activity is developed using ruthenium nanoparticles as the active metal supported on ceria and promoted with cesium to mitigate hydrogen and ammonia inhibition, respectively. This catalyst is compared to commercial iron-based catalyst from the perspective of the final application. Concurrently, a high-temperature (> 300°C) manganese chloride absorbent is developed that resists decomposition and is stable when supported on silica. These catalyst and absorbent are integrated in a layered reactor configuration to demonstrate the feasibility of the integrated process by exceeding single-pass reaction equilibrium. Mathematical modelling of ammonia production processes illustrates that at small-scales (< 1 t day-1) the single-vessel process is optimal compared to the Haber-Bosch process due to its modular design. In addition, it can achieve simpler ramping because the Haber-Bosch process is constrained by heat-integration in the recycle loop and the potential for runaway reaction. For final application, the pairing of ammonia production processes with examples of intermittent solar and wind sources demonstrates that the flexibility of the production process is essential when considering non-ideal sources of energy with a long-term (e.g. seasonal) oscillations. Flexible ammonia production also expands the economic usage of ammonia as an energy storage vector from the seasonal to the weekly time-scale, with advantage compared to batteries or hydrogen. The work of this thesis provides a framework for advancing the electrification of the chemical industry given the novel constrains of intermittent and distributed renewable energy. A systems level approach is applied from the ground up, starting from material design and progressing to optimized process design and application.

The aggravating global problems of energy crisis, rising atmospheric greenhouse gas concentrations and accumulation of persistent waste have attracted the attention of scientists, policy-makers and global organisations to come up with effective and expeditious solutions to address these challenges. In this context, the development of sustainable technologies driven by renewable energy sources for the production of clean fuels and commodity chemicals from diverse waste feedstocks is an appealing approach towards creating a circular economy. Over the years, semiconductor photocatalysts based on TiO₂, CdS, carbon-nitrides (CNx) and carbon dots (CDs) have been widely used for the photocatalytic reforming (PC reforming) of pre-treated waste substrates to organic products, accompanied with clean hydrogen (H₂) generation. However, these conventional solar-driven processes suffer from major drawbacks such as low production rates, poor product selectivity, CO₂ release, challenging process and catalyst optimisation, and harsh waste pre-treatment conditions, which limit their commercial applicability. These challenges are tackled in this thesis with the introduction of new and efficient photoelectrochemical (PEC) and chemoenzymatic processes for reforming a diverse range of waste feedstocks to sustainable fuels. Solar-driven PEC reforming based on halide perovskite light-absorber is first developed as an attractive alternative to PC reforming. The PEC systems consist of a perovskite|Pt photocathode for clean H₂ production and a Cu-Pd alloy anode for reforming diverse waste streams, including pre-treated cellulosic biomass, polyethylene terephthalate (PET) plastics, and industrial by-product glycerol into industrially-relevant, value-added chemicals (gluconic acid, glycolic acid and glyceric acid) without any externally applied bias or voltage. Additionally, the single light-absorber PEC systems can also convert the airborne waste stream and greenhouse gas CO₂ to diverse products with the simultaneous reforming of PET plastics with no applied voltage. The perovskite-based photocathode enables the integration of different CO₂ reduction catalysts such as a molecular cobalt porphyrin, a Cu-In alloy and formate dehydrogenase enzyme, which produce CO, syngas and formate, respectively. The versatile PEC systems, which can be assembled in either a ‘two-compartment’ or standalone ‘artificial leaf’ configurations achieve 60‒90% oxidation product selectivity (with no over-oxidation) and >100 µmol cm‾² h‾¹ product formation rates, corresponding to 10²‒10⁴ times higher activity than conventional PC reforming systems. In addition to developing PEC platforms, this thesis also explores avenues for circumventing the harsh alkaline pre-treatment strategies (pH >13, 60‒80 ºC) adopted for photoreforming waste substrates. For this purpose, a chemoenzymatic pathway is introduced whereby PET and polycaprolactone plastics were deconstructed using functional enzymes under benign conditions (pH 6‒8, 37‒65 ºC), followed by PC reforming using Pt loaded TiO₂ (TiO₂|Pt) or Ni₂P loaded carbon-nitride (CNx|Ni₂P) photocatalysts. The chemoenzymatic reforming process demonstrates versatility in upcycling polyester films and nanoplastics for H₂ production at high yields reaching ∼10³‒10⁴ µmol gsub‾¹ and activities at >500 µmol gcat‾¹ h‾¹. The utilisation of enzyme pre-treated plastics also allowed the coupling of plastic reforming with photocatalytic CO₂-to-syngas conversion using a phosphonated cobalt bis(terpyridine) co-catalyst immobilised on TiO₂ (TiO₂|CotpyP). Finally, moving beyond solar-driven systems, a bio-electrocatalytic flow process is demonstrated for the conversion of microbe pre-treated food waste to ethylene (an important feedstock in the chemical industry) on graphitic carbon electrodes via succinic acid as the central intermediate. In conclusion, with its focus on improving efficiencies, achieving selective product formation, building versatile platforms, diversifying substrate and product scope, and reducing carbon footprint and economic strain, this thesis aims to bring sustainable waste-to-fuel technologies a step closer to commercial implementation.

Boreal forests hold 32% of the world’s terrestrial organic matter and are continually disturbed by biotic and abiotic events. These disturbances are especially important since they facilitate the redistribution of nutrients within and between ecosystems, which can alter resource use and productivity. Yet how various types of disturbances, both individually and in combination, impact the overall resource balance of northern forests remains poorly understood. This thesis aims to advance our understanding of forest disturbances as drivers of forest resource balances, primarily through shifts in carbon, to better facilitate management of forests under climate change. Chapter 1 reviews current knowledge on forest disturbances and cross- ecosystem linkages. It also provides a summary of current gaps in our understanding of disturbances as drivers of forest function and possible downstream effects. Chapter 2 explores how disturbance history influences long-term carbon balance in boreal forests. Theory predicts that disturbances will increase with climate change but how the order and timing of multiple disturbance events will impact ecosystem function remains unresolved. Chapter 3 extends our understanding of forest carbon balance by asking how different disturbance types change the phenology and surface reflectance of boreal forests. Understanding how single disturbance events change growing season length and radiative forcing of forests can help predict potential feedbacks of forest health on climate warming. Chapter 4 tests how outbreaks of defoliating insects alter biogeochemical cycling from land to receiving waters through the consumption of foliage and subsequent release of nutrient-rich waste. Forests typically provide a pulse of nutrients to nearby waters in autumn when leaves are shed but insects disrupt this pattern by changing the timing, quantity, and quality of resource transfers. Chapter 5 traces terrestrial nutrients within lakes and asks if they can promote productivity in zooplankton communities. Finally, Chapter 6 discusses the main findings of the thesis and ends with possible directions for future research.