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Changing the decision context to enable social learning for climate adaptation
No full textInternational audienceSuccessful adaptation often involves changes to the decision context to enable new ways of thinking and acting on climate change. Using 16 adaptation initiatives the authors were engaged with, we analysed how and why decision contexts changed to identify ways to improve adaptation as a process of collective deliberation and social learning. We used the scope of the adaptation issue and governance arrangements to classify initiatives into four types and scored changes in the decision context using three frameworks: (1) the values, rules and knowledge (VRK) perspective to identify changes to adaptation decision‐making; (2) the five dimensions of futures consciousness to identify the building of adaptation capabilities and (3) the social learning cycle to reveal evidence of reflexive learning. Initiatives using novel governance arrangements for discrete problems (‘problem governance’) or complex, systemic issues (‘systems governance’) scored highest for influences of VRK, futures consciousness and the social learning cycle on the decision context. Initiatives using existing management for discrete problems (‘problem management’) scored moderately for change in the decision context, while those using existing management for systemic issues (‘systems management’) scored low because change was often impeded by existing rules. All three frameworks influenced decision contexts in systems governance initiatives. Problem governance initiatives revealed interactions of VRK and futures consciousness but limited influence of VRK on the social learning cycle. Scope and governance arrangements differ with the adaptation issue and initiatives adapt over time: some small‐scale ones became more systemic, developed novel governance arrangements and changed the decision context. Our findings do not show that some adaptation initiatives are better or more transformative than others; just that their scope and appropriate governance arrangements are different. This questions the notion that successful adaptation requires building generic transformative adaptation approaches and capabilities. There is a diversity of arrangements that work. What is important is to align the approach to the adaptation problem. We suggest two directions for improving adaptation initiatives: first, by influencing how they can shift between problem and systems focus and between standard management and novel governance, and secondly, by using methods to diagnose and direct change in the decision context. Read the free Plain Language Summary for this article on the Journal blog
Within-country inequality and the shaping of a just global climate policy
No full textDocuments de travail du Centre d'Economie de la Sorbonne 2025.09 - ISSN : 1955-611XClimate change and global inequality are intertwined. First, from a cross-country perspective, poorer countries have less financial capacity to abate emissions and are more vulnerable to climate impacts. Second, within countries, climate damages and mitigation costs tend to fall disproportionately on poorer households, which has implications for the political feasibility of mitigation. Integrated Assessment Models used for global climate policy evaluation have so far typically not considered inequality effects within countries. To fill this gap, we develop a global Integrated Assessment Model representing national economies and sub-national income distribution, and assess a range of climate policy schemes with varying levels of effort sharing across countries and households. The schemes are consistent with limiting temperature increases to 2°C, and account for the possibility to use revenues from carbon pricing to address distributional effects within and between countries. Among these, we explore a "Loss and Damage" scheme, aiming to compensate vulnerable countries for unavoidable damages from climate change. A key finding is that relatively low levels of international transfers can result in sizable improvements in inequality and welfare, due to the impacts on the most vulnerable households within countries. If international transfers are not feasible, our results show that the greatest inequality reductions can be achieved through sub-national transfers and reallocation of abatement efforts across time and countries
Inequality and Agricultural Structural Change: Evidence from Macro and Microdata , 1950-Present
No full textSince 1950, agricultural productivity has been increasing even as labourers leave agriculture. However, while average productivity of the sector has been converging, withinsector inequality has been increasing. Agricultural income inequality is still less than overall income inequality, but it measures significantly higher when we use higher-quality and more comprehensive survey data. This means not only to observe the entirety of household farm income, but also to measure the magnitude of capital income and corporate profits in the sector. Given the likely increase in agricultural inequality during the process of structural change, I show also the extent to which social protection programmes are both insufficient a nd poorly targeted for rural populations
The New Titan Planetary Climate Model. II. Titan’s Haze and Cloud Cycles
No full textInternational audienceObservations of Titan have long revealed the presence of seasonal cycles, including haze, clouds, and gases. The lack of information on the different processes that govern these cycles prevents us from understanding all the phenomena taking place in Titan’s atmosphere. In this work, we survey Titan’s cycles exhaustively to understand their mechanisms, in particular the haze and cloud cycles that govern a large part of Titan’s climate and its surface. The Titan Planetary Climate Model (Titan PCM)—an upgraded version of the IPSL Titan Global Climate Model—incorporates a microphysical model for haze and clouds, along with a methane cycle (evaporation, transportation, condensation, precipitation). The model also features improved radiative transfer and updated spectroscopic data on gases. The Titan PCM includes phenomena hitherto omitted from Titan 3D simulations, such as cloud nucleation and condensation. Furthermore, we have coupled microphysics with radiative transfer in order to take account of feedback from haze and clouds on the thermal structure. We find that the haze follows a seasonal cycle constrained by the pole-to-pole circulation in the stratosphere. Below, the cold regions between 30 and 90 km trigger the condensation of minor species, forming a condensate mist layer throughout the year. Methane clouds form near the surface (5–25 km), in the ascending branches of the circulation, while polar clouds form higher up (60–300 km) at the winter pole after enrichment in trace compounds. The Titan PCM now enables detailed exploration of the long-term variations in Titan’s cycles, providing insights for future observations
The key role of motorized two-wheelers in boosting the earnings of on-demand delivery workers in Paris
No full textInternational audienceIn France, earnings from delivery workers involved in on-demand instant delivery are not well known. Using data from two waves of a survey conducted in Paris with instant delivery workers, this research presents the interactions between types of delivery gigs, operations and vehicles that lead to differences in income earned from delivery. The results show that the highest incomes are found among delivery workers with the longest service and who work for multiple delivery platforms. More importantly, using a motorized two-wheeler instead of a bicycle, e-bicycle, or scooter is key. It seems to be the best way to ensure a good level of earnings for on-demand instant delivery workers. However, there are legal and environmental dilemmas. Primarily, French law mandates that freelance delivery drivers obtain a specific license before utilizing mopeds for delivery purposes, a license that most of them do not have. Moreover, the energy consumption of mopeds is higher than that of bicycles and electric scooters by a factor of twenty, presenting significant environmental concerns
On Arrangements of Quadrics in Decomposing the Parameter Space of 3D Digitized Rigid Motions
No full textInternational audienceComputing the arrangement of quadrics in 3D is a fundamental problem in symbolic computation, with challenges arising when handling degenerate cases and asymptotic critical values. State-of-the-art methods typically require a generic change of coordinates to manage these asymptotes, rendering certain problems intractable. A specific instance of this challenge appears in digital geometry, where comparing 3D shapes up to isometry requires applying a 3D rigid motion on and mapping the result back to , a process typically achieved via a digitization operator. However, such motions do not preserve the topology of digital objects, making the analysis of digitized rigid motions crucial. Our main contribution is the decomposition of the 6D parameter space of digitized rigid motions for image patches of radius up to three. This problem reduces to computing the arrangement of up to 741 quadrics, some of which are degenerate. To address the computational challenges, we introduce and implement a new algorithm for computing arrangements of quadrics in 3D, specifically designed to handle degenerate directions and asymptotic critical values. This approach allows us to overcome the limitations of existing methods, making the problem tractable in the context of digital geometry
Shannon Weights for binary dynamical recurrent sources of zero entropy
No full text51 pages, 3 figuresA probabilistic source is defined as the set of infinite words (over a given denumerable alphabet) endowed with a probability . The paper deals with general binary sources where the distribution of any symbol (0 or 1) may depend on an unbounded part of the previous history. The paper studies Shannon weights: whereas the classical Shannon entropy is the average amount of information brought by one symbol of the emitted word, the Shannon weight sequence deals with the average amount of information that is brought by the emitted prefix of length . For a source with a non zero entropy, the estimate thus holds. The paper considers the model of dynamical sources, where a source word isemitted as an encoded trajectory of a dynamical system of the unit interval, when endowed with probability . It focus on sources with zero entropy and gives explicit constructions for sources whose Shannon weight sequence satisfies , with a prescribed behaviour. In this case, sources with zero entropy lead to dynamical systems built on maps with an indifferent fixed point. This class notably contains the celebrated Farey source, which presents well-known intermittency phenomena. Methods are based on analytic combinatorics and generating functions, and they are enlarged, in the present dynamical case, with dynamical systems tools (mainly transfer operators)
CREMSA: Compressed indexing of (ultra) large multiple sequence alignments
No full textInternational audienceRecent viral outbreaks motivate the systematic collection of pathogenic genomesin order to accelerate their study and monitor the apparition/spread of variants. Due to their limited length and temporal proximity of their sequencing, viral genomes are usually organized, and analyzed as oversized Multiple Sequence Alignments (MSAs). Such MSAs are largely ungapped, and mostly homogeneous on a column-wise level but not at a sequential level due to local variations, hindering the performances of sequential compression algorithms. In order to enable an efficient handling of MSAs, including subsequent statistical analyses, we introduce CREMSA (Column-wise Run-length Encoding for Multiple Sequence Alignments), a new index that builds on sparse bitvector representations to compress an existing or streamed MSA, all the while allowing for an expressive set of accelerated requests to query the alignment without prior decompression. Using CREMSA, a 65GB MSA consisting of 1.9M SARS-CoV 2 genomes could be compressed into 22MB using less than half a gigabyte of main memory, while executing access requests in the order of 100ns. Such a speed up enables a comprehensive analysis of covariation over this very large MSA. We further assess the impact of the sequence ordering on the compressibility of MSAs and propose a resorting strategy that, despite the proven NP-hardness of an optimal sort, induces greatly increased compression ratios at a marginal computational cost
Lobbying for Globalisation
No full textInternational audienceUsing detailed information from lobbying reports filed under the Lobbying Disclosure Act, we construct a unique dataset that allows us to identify which firms lobby on Free Trade Agreements (FTAs) negotiated by the United States, their position (in favour or against) and their lobbying effort on the ratification of each trade agreement. Using this dataset, we show that lobbying on FTAs is dominated by large multinational firms, which are in favour of these agreements. On the intensive margin, we exploit exogenous variation across FTAs to show that individual firms put more effort supporting agreements that generate larger potential gains – larger improvements in their access to foreign consumers and suppliers and smaller increases in domestic competition – and that are more likely to be opposed by politicians. To rationalise these findings, we develop a new model of endogenous lobbying on trade agreements. In this model, heterogeneous firms select into trade and choose whether and how much to spend lobbying on the ratification of an FTA, and politicians may be biased in favour of or against the agreement
Large-Scale Evacuation with Vehicular Communication: Navigating Through Dark Zones
No full textInternational audienceIn times of disaster, ensuring the safe evacuation of affected populations is crucial for saving lives and mitigating community risks. This research presents a Dynamic Population Evacuation (DPE) approach, which combines strategic planning and real-time management aided by vehicular communication technology. By addressing the impact of disasters on transportation and communication systems, the DPE framework utilizes dynamic shelter allocation and simulation-based traffic assignment techniques to enhance planning accuracy. It incorporates a trip-based traffic simulator to account for the effects of disasters on transportation networks and a Vehicular Ad Hoc Network (VANET) simulator to manage communication dark zones. To manage dark zones, The proposed framework continuously updates the evacuation plan in real time to manage road blockages and the disabling of VANET resources. Accounting for the temporal evolution of areas with communication dark zones improves evacuation efficiency regarding clearance time. A sensitivity analysis is conducted on the compliance rate of evacuees to instructions provided by the vehicular communication management system. Furthermore, the framework's effectiveness is evaluated by simulating the real test case of the 2018 Camp Fire wildfire in Paradise, California, where roads and communication were severely disrupted. Additionally, by comparing the architectures of cloud computing and fog computing while accounting for blocked roads, the framework shows more than a 12% improvement in network clearance time compared to fog computing and a 19% improvement compared to traditional evacuation planning