Promoting urban greenery through tree planting strategies has been considered as a measure to mitigate climate change. While it is essential to understand the temporal dynamics of urban forest... Show morePromoting urban greenery through tree planting strategies has been considered as a measure to mitigate climate change. While it is essential to understand the temporal dynamics of urban forest structure as well as its services and contribution to human wellbeing in cities, it has hardly ever been examined whether the future contributions of these services after different possible planting strategies can comply with climate change policy goals; these are topics rarely discussed in urban planning and management. In this paper, the ecosystem services currently provided by urban trees (through carbon sequestration and storage), as well as those potentially provided in the future, were quantified using the i-Tree Eco model, and their contribution to climate change mitigation was evaluated. As a case study in Tabriz, Iran, we developed four possible scenarios. Synergy (urban temperature regulation by UF) and trade-off (tree water requirements) were also analyzed. Future carbon sequestration and storage potential of urban trees was compared with the estimated future carbon emissions. The current contribution in Tabriz is relatively modest (about 0.2%), but it can be tripled through long-term tree planting strategies. Additionally, the temporal cooling effects and tree water requirements increase as climate change mitigation improves through tree planting. We conclude that urban tree planting has a small impact on carbon mitigation in the study area, most likely because of the young age of trees in Tabriz as well as the fact that the planted trees cannot deliver all their benefits over a 20-years period and need more time. Thus, the use of urban trees serves only as a complementary solution rather than an alternative climate mitigation strategy. Our quantitative approach helps urban environmental policymakers to evaluate how much they can rely on urban forest strategies to achieve climate change mitigation targets. Show less
Looking for a global and corrective measure to reduce greenhouse gas emissions from international civil aviation has been facing legal obstacles. These obstacles took the form of conflicts of... Show moreLooking for a global and corrective measure to reduce greenhouse gas emissions from international civil aviation has been facing legal obstacles. These obstacles took the form of conflicts of norms linked to the general challenge of the interactions between international aviation law, climate change law and the law of the European Union. Using evolutionary interpretation of the Chicago Convention in order to reconcile norms of substantive and institutional nature emerged as the best solution. However, this method perpetuates legal uncertainty and poses the general challenge of flexibly and elasticity of the Chicago Convention in response to the climate change challenge. This study examines the above mentioned issues of interactions between legal orders and provides recommendations to restore legal certainty needed to ensure sustainable development of international civil aviation. More specifically, this study reveals the underestimated relevance of the ongoing distinction between the legal regimes of air navigation and international air transport, which is a key legal element in the search for a global and corrective solution to the impact of international civil aviation on climate change. Show less
