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This synthesis paper presents the objectives, approach and cross-cutting results of the Latin American Deep Decarbonization Pathways project (DDPLAC). It synthesizes and compares detailed national and sectoral deep decarbonization pathways (DDPs) to 2050 compatible with the Paris Agreement objectives and domestic development priorities in Argentina, Colombia, Costa Rica, Ecuador, Mexico and Peru. The first five countries analysed in detail the energy system and agriculture, forestry and land use (AFOLU) at a high level, while Peru focussed on a detailed analysis of AFOLU given its predominance in its GHG emissions. While economy-wide results were produced, this paper focuses on the electricity, passenger transport, and AFOLU results because of their current emissions, potential to grow, and identification of successful strategies for decarbonization (e.g. switching to clean electricity and switching to other net- zero fuels across the economy; urban planning, mode shifting, and electrification in passenger transport; and intensive sustainable agriculture, assignment of land use rights and their enforcement and afforestation in AFOLU). It also highlights where significant emissions remain in 2050, notably in industry, AFOLU, freight, and oil and gas production, all areas for future research. It also derives insights for the design of domestic policy packages and identifies priorities for international cooperation. This analysis provides critical information for Long-Term Strategies, Nationally Determined Contributions and Global Stocktaking in the context of the Paris Agreement.

Green fiscal reforms would contribute to climate change mitigation, increase the economic efficiency of national tax systems and provide additional public revenues. Some countries in Latin America have already taken first steps towards green fiscal reforms. This paper provides an overview of the major challenges for the successful implementation of such reforms and discusses how they could be overcome. The authors first discuss the role of country-specific economic and political enabling conditions that need to be in place for successful implementation for green successful reforms. Second, they emphasize the importance of comprehensive reform plans that include all relevant ministries and agencies and are well-aligned with other policy objectives, such as energy security and industrial development. Third, they highlight how appropriate sequencing and gradualism could lower implementation costs and hence increase the political feasibility of green fiscal reforms. Finally, the authors analyze the potential impacts of green fiscal reforms on the distribution of income and discuss transfer schemes that could avoid adverse outcomes for the poorest parts of the population. They use these four dimensions to illustrate why recent reform efforts in selected Latin American countries have been successful or have failed, respectively.

[cat] En l'entramat metabòlic cel·lular, milers de substrats estan interconnectats mitjançant reaccions bioquímiques. Tot i que aquest alt grau d'interrelació podria conduir al flux de substrats en múltiples direccions simultàniament, a la pràctica els fluxos metabòlics passen a través de rutes específiques. Els nostres estudis evolutius sobre el metabolisme del glicogen mostren que els isoenzims que catalitzen les diverses etapes d'aquesta ruta contribueixen a definir i a aïllar els mòduls funcionals, un punt clau per entendre la organització metabòlica en els vertebrats. Aquests isoenzims específics de teixit sorgeixen per duplicació gènica a l'origen dels vertebrats i que les seves propietats bioquímiques co-evolucionen per adaptar-se a les necessitats metabòliques específiques dels teixits on s'expressen. La retroinhibició de les hexoquinases d'alta afinitat o l'activació al·lostèrica de les glicogen sintases, ambdós efectes mediats per la glucosa-6-fosfat, són clars exemples de que les característiques cinètiques dels isoenzims es modulen al llarg de l'evolució dels vertebrats per satisfer les diferents funcions del metabolisme del glicogen. A més, els nostres resultats ajuden a entendre la única situació descrita on, paradoxalment, els isoenzims del metabolisme del glicogen majoritaris en cervell, múscul i fetge es barregen i es co-expressen en el mateix teixit: el fetge embrionari de mamífer. Els resultats presentats en aquesta memòria indiquen que la síntesi de glicogen en el fetge embrionari, essencial per assegurar la supervivència del nounat, requereix la re-organització de l'expressió dels isoenzims que hi participen, a fi d'estabilitzar el contingut de glicogen embrionari en front de les variables condicions fisiològiques maternes. Estudis previs indicaven que els ratolins defectius per la isoforma muscular de la glicogen sintasa mostren greus defectes en el desenvolupament cardíac. Per aprofundir en les bases moleculars d'aquesta alteració, hem caracteritzat la translocació nucleo-citoplàsmica de la glicogen sintasa muscular humana i hem analitzat la seva funció en el nucli. Els nostres resultats mostren com aquest enzim transloca vers al nucli i forma agregats nuclears quan es deplecionen les reserves de glicogen de la cèl·lula. A més, els resultats obtinguts amb els mutants de deleció de l'enzim indiquen que el domini implicat en l'activació al·lostèrica de l'enzim per G6P, la regió rica en arginines, és crucial per a la seva acumulació nuclear. En conjunt, aquestes observacions suggereixen que, a part de la funció metabòlica, la glicogen sintasa podria participar en processos nuclears on es requerís un sensor de l'estat energètic de la cèl·lula., [eng] In the metabolic network of the cell, hundreds of substrates are interconnected through biochemical reactions. Although such interconnection could lead to the simultaneous flow of substrates in numerous directions, in practice metabolic fluxes pass through specific pathways. Our metabolic and evolutionary studies on glycogen metabolism showed that isoenzymes contribute to define and isolate separate functional modules, a key issue to understand metabolic organisation in vertebrates. These tissue-specific isoenzymes are generated by gene duplication at the dawn of vertebrates and their biochemical properties co-evolved to suit specific metabolic roles of the tissues where they are expressed. The retro inhibition of high-affinity hexokinases, or glycogen synthase allosteric activation, both effects mediated by G6P, are clear examples of kinetic features that are modulated through vertebrate evolution to satisfy different roles of glycogen metabolism. Furthermore, our results help to understand the only reported situation where, paradoxally, isoenzymes of glycogen metabolism enzymes from liver, muscle and brain are merged and co-expressed in the same tissue: the mammalian embryonic liver. Our results indicate that embryonic glycogen synthesis in liver, essential for newborn survival, requires the re-design of isoenzyme distribution in order to buffer the embryonic glycogen content in front of changing maternal metabolic conditions. In addition, it has been described that muscle glycogen synthase isoenzyme (MGS) knockout mice show severe developmental heart defects. In order to adress the molecular basis of this growth alteration, we characterised the nucleo-cytoplasmic translocation of MGS and analyzed its nuclear function. We showed that this enzyme translocate into the nucleus and form nuclear aggregates when cells are depleted of glucose and glycogen deposits. Moreover, the results that we obtained with the deletion mutants indicate that the domain involved in the allosteric activation of the enzyme by G6P, the arginine-rich cluster, is crucial for its nuclear acumulation. Taken together, these observations suggest that, in addition to its metabolic function, MGS may participate in nuclear processes which would require a sensor of the cellular enregy state.