Energy system planning has evolved from a narrow focus on engineering and supply works towards addressing more complex, multifactorial challenges. Increasingly challenged by climate change, extreme events, economic shocks, and altered supply demand patterns, the analysis of energy systems requires holistic approaches based on data-driven models, taking into account key socio-economic factors. We draw insights from reviewing the literature, indicating the need to cover the following major gaps: the shift to transdisciplinary approaches, incorporating environmental system analysis; resilient and sustainable energy designs based on flexible portfolios of renewable mixes; the integration of socio-economic aspects, economic analyses and behavioural models to ensure energy systems are not only technically sound but socially acceptable and viable; the need for stakeholder engagement considering the human angle in energy security and behavioural shifts. Responding to these pressing challenges and emerging needs, the Global Climate Hub (GCH) initiative, operating under the UN Sustainable Development Solutions Network, offers a conceptual framework, leveraging transdisciplinary approaches. In this Concept Paper, we present for the first time the idea of the GCH as a framework that we believe has the potential to address the modern holistic needs for energy system analysis and policymaking. By setting the conceptual/theoretical ground of our suggested approach, we aim to provide guidance for innovative combinations of cutting-edge models, socio-economic narratives, and inclusive interaction with relevant stakeholders for the development and the long-term implementation of sustainable pathways.

Achieving climate-neutrality is a global imperative that demands coordinated efforts from both science and robust policies supporting a smooth transition across multiple sectors. However, the interdisciplinary and complex science-to-policy nature of this effort makes it particularly challenging for several countries, both in terms of planning and implementation, especially for countries that were not traditionally used to such holistic governance. There are several examples in the literature coupling different models representing different sectors (e.g. water-energy-food-emissions). However, the use of such integrated models assessing climate-neutrality and decarbonization pathways is rarer.Greece is an example, and its preparedness to address such challenges is often debated. For the first time, we simulated Greece’s climate-neutrality efforts, within a water-energy-food-emissions nexus context, combining models such as LEAP (energy-emissions), FABLE Calculator (food and land use), and WaterReqGCH (water accounting tool). The Greek National Energy and Climate Plan (NECP) was simulated, to evaluate its expected outcomes, and provide insights into its effectiveness. The goal of this novel approach is to provide useful insights on whether the NECP can achieve the climate neutrality goals, and how we can see it as an opportunity for a broader (nexus-oriented) sustainable transition. The results indicate that the NECP, if implemented, has the potential to significantly reduce carbon emissions across all sectors of the economy (residential, industrial, transport, services, agriculture, and energy production). However, that would require its proper implementation, which in turn requires certain behavioural changes (e.g. adoption of technologies to improve energy efficiency and mixes of cleaner fuels). Moreover, it falls short of achieving a more holistic sustainable transition if not considered as part of a broader suite of policies that can concurrently address agriculture, water resource management, and socio-economic dimensions.

Despite growing global momentum for achieving the Sustainable Development Goals (SDGs), monitoring and reporting progress at the regional level remains limited

Achieving climate neutrality in Europe is a critical goal, yet there is no model-based assessment detailing the key factors and assumptions of each Member State’s National Energy and Climate Plan (NECP). To fill that gap, the plans of 35 European countries (33 NECPs and the equivalent national plans of Norway and Switzerland) were reviewed, and each was simulated in a common energy emissions modeling framework, creating a consolidated European National Commitments (NC) scenario that assumes full implementation of the plans. The LEAP (Low Emissions Analysis Platform) model developed for this purpose covers energy consumption and production in the residential, industrial, agricultural, transport (terrestrial, maritime, aviation), and services sectors. Greenhouse gas emissions are calculated in CO₂ equivalents for each fuel type and end use. Under the NC scenario, energy-related GHG emissions fall by about 65% between 2025 and 2050, with reductions in all sectors, driven by energy efficiency gains and cleaner fuel mixes. Yet the plans are not mutually consistent: summed over all countries, they imply net imports of 115 TWh of electricity and 79 TWh of green hydrogen in 2050 that no European plan foresees supplying. However, achieving these reductions depends on fully implementing 35 plans, which vary substantially in their timelines, ambition levels, data granularity, and fuel trade assumptions. The paper discusses these inconsistencies and proposes policy recommendations tailored by sector, country, and policy framework to support a holistic and equitable transition.