10 years of the Paris Climate Agreement – Interview with systems scientist Prof. Dr Jochen Linßen
The Paris Climate Agreement: Between climate targets and emissions trends
What is needed for Germany and Europe to actually achieve the energy transition? Where do we stand today, and what options are on the table? To mark the tenth anniversary of the Paris Climate Agreement, Prof. Dr Jochen Linßen from Forschungszentrum Jülich provides insights.
Ten years ago, the international community agreed in Paris to limit global warming. Since then, one thing has become clear: climate protection requires more than just targets – it needs a robust framework. This is precisely what Prof. Dr Jochen Linßen is working on at the Jülich Research Centre (FZJ). As head of the Jülich Systems Analysis group at the Institute for Climate- and Energy Systems (ICE-2), he is investigating how Germany and Europe can transform their energy systems without losing sight of security of supply, economic viability and the environment. To this end, his team uses complex models which, put simply, function like ‘what-if machines’: they calculate how various political, technical and societal decisions might affect the future of energy. The resulting scenarios do not predict the future – but they do show which paths are realistic and sensible.
10 years of the Paris Climate Agreement. Looking back over this decade: where do we stand today in terms of climate targets?
Although the trend of rising CO₂ emissions has slowed globally, there is certainly no cause for complacency. In 2024, man-made emissions will reach a new all-time high of almost 38 billion tonnes – in 1990, the figure was just over 22 billion, representing a rise of around 70 per cent despite all the climate agreements. There is no sign of a reversal in the trend towards falling greenhouse gas emissions.
Even more seriously, several major economies have so far failed to meet the climate targets they set for themselves under the Paris Agreement. Yet it is precisely this agreement that commits the international community to limiting global warming to well below 2 °C – and ideally to 1.5 °C – compared with pre-industrial levels.
The consequences of this failed climate policy have long been evident. With every tenth of a degree of additional warming, the risks to ecosystems, societies and economies increase. And one thing is economically clear: in the long term, the costs of increasing climate damage will exceed the expenditure on consistent climate protection. The damage caused by man-made climate change will be borne by future generations.
Germany’s energy transition: progress and the need for action
Where does Germany stand in this development?
As Europe’s most populous and economically strongest country, Germany bears a special responsibility for European climate protection targets. This role is not merely a political aspiration, but also an obligation.
The Climate Protection Act of 2022 – mandated by the Federal Constitutional Court – provides the central framework: it sets out binding climate protection and sectoral targets and establishes the path to net greenhouse gas neutrality by 2045. Germany, and indeed Europe as a whole, have made significant progress to date. However, the current course of action alone will not be enough.
The next stages will require significantly more ambitious measures, underpinned by technological innovation, new business models and consistent political implementation.
What do your scenario studies show: Are the climate targets realistic – and under what conditions?
Our research and model analyses at Forschungszentrum Jülich clearly show that the transformation of the energy system is technically feasible and even makes economic sense. It is crucial that we set the right course early on. There is not just one way forward: our models and scenarios reveal a whole range of realistic options and highlight which steps are crucial today and in the coming years to achieve the targets.
Just to give an example: if the rapid and targeted expansion of wind and solar power is successful, transport and buildings will also benefit – because, through what is known as ‘sector coupling’, renewable electricity can be intelligently used directly to power electric vehicles and heat pumps. This significantly reduces the demand for oil and natural gas and lessens dependence on individual countries. Such interconnections illustrate just how strongly today’s decisions influence tomorrow’s energy system and security of supply.
This is precisely where a major opportunity lies: those who consistently make use of options arising from research and development now can bring new innovations from the prototype stage to widespread application more quickly. In this way, competitiveness and climate protection can be strengthened together, enabling us to actively shape the transition – rather than having to react later under greater pressure.
The 2022 natural gas crisis – all too quickly forgotten – triggered by Russia’s war of aggression against Ukraine, clearly demonstrated how vulnerable the economy and society are to sudden shortages of fossil fuels. Our models have also clearly shown this: a greenhouse gas-neutral energy system is significantly less vulnerable and enhances the geostrategic security of energy supply. Greater resilience is not a by-product, but an integral part of the transition.
A move away from ambitious climate protection would therefore be counterproductive, both economically and socially. Climate action has long been part of modern value creation. At the same time, potential competitive disadvantages for industry in global trade must be mitigated through political and economic measures such as support schemes for climate-friendly production processes or reliable, globally applicable CO₂ prices. It is crucial to consider competitiveness, climate and environmental protection, and resilience as an integrated whole.
What specific questions from politicians, ministries or public authorities land on your desk – and how do your models help to find answers to them?
Time and again, we are asked key questions about the future of the energy system: How secure is the supply during periods of low wind and low sunshine? Can Germany, together with Europe, become less dependent on fossil fuel imports? What infrastructure and technologies need to be in place by when to achieve this goal? How are renewable energies stored and transported, and where are they used?
These are legitimate questions – and they can only be answered using sound scientific methods and models. With our ETHOS modelling suite, we investigate these questions by mathematically modelling Germany’s energy system – from electricity and heating networks through industrial processes to global energy flows. Using ETHOS, for example, we calculate which combination of technologies ensures a reliable yet cost-effective supply, how much renewable energy is required to achieve this, and where bottlenecks might arise. Our ETHOS modelling suite makes precisely such analyses possible. It enables unbiased, scientifically sound investigations into technologies, transition pathways, value chains and market ramp-ups in future energy systems. In doing so, we consider not only technical developments such as batteries, grid expansion or potential long-term options such as nuclear fusion, but also political, economic and societal framework conditions, such as planning permission regulations for wind turbines or the public acceptance of new energy technologies. Our scenarios make these interrelationships transparent and provide policymakers, government, industry and academia with a sound basis for decision-making.
How reliable are these scenarios?
Energy scenarios bring together technical, societal and environmental dimensions and provide an overall picture of a highly complex system. They highlight possible solutions and options – but should not be confused with forecasts.
Forecasts attempt to predict the future, much like a weather forecast. But just as there cannot be a reliable weather forecast for the next 25 years, it is equally impossible to make an exact prediction of the future national or global energy system.
What scenarios do achieve, however, is to show which paths are possible, which decisions would be necessary, and what consequences different paths would entail. This is precisely what makes them an indispensable tool for fact-based, responsible energy and climate policy.
When we speak again on the 20th anniversary of the Paris Climate Agreement: what do you hope to be able to say about the energy transition in Germany?
I hope to be able to say that Germany has succeeded in making the transition from ambitious plans to decisive action – and in doing so, has demonstrated that climate protection and economic strength are not mutually exclusive. That key technologies have made their breakthrough, from renewable energy systems to high-performance storage solutions and a functioning hydrogen infrastructure.
And I hope that our analyses have helped to chart a reliable course along this path: by providing guidance, highlighting risks and identifying options. If we achieve this, then the energy transition will not only succeed – it will be a competitive advantage for Germany and Europe.
Source: Jülich Research Centre
Energy scenarios and climate protection
In brief: What is crucial for the energy transition
- The transformation is achievable: According to Jochen Linßen, Jülich’s model analyses show that the restructuring of the energy system is technically feasible and economically viable. Setting the course early on and consistent implementation are crucial.
- Renewable energies have a cross-sectoral impact: Through sector coupling, electricity from wind and solar power can also supply electric vehicles and heat pumps. This helps to reduce the demand for oil and natural gas.
- Scenarios provide guidance: The ETHOS modelling suite examines possible transformation pathways and their consequences. The results support decision-making but are not predictions.
- Climate protection and security of supply go hand in hand: According to Linssen’s assessment, a greenhouse gas-neutral energy system is less vulnerable to fossil fuel supply crises. Competitiveness, climate protection and resilience must be considered together.