Adobe Stock / Radmila Merkulova
Climate-damaging subsidies in transport undermine CO2 pricing
A reward of several hundred euros for a ton of CO2
The Ariadne calculations emphasise that Germany’s current tax system in the transport sector is still dominated by the use of fossil fuels, making it more difficult to achieve the country’s climate targets.
Denis Yevtekhov / Adobe Stock
Mapping variation in institutions for climate policymaking
Effective climate governance through strong climate institutions
In a report, Ariadne researchers offer reform options for German climate institutions in the context of the Klimaschutznovelle.
Antoine Schibler / Unsplash
Political consensus for EU emissions trading for heat and transport
Fair design and economically efficient price
In two recent publications, Ariadne experts have analysed various design options, specifically looking at the carbon pricing and relief options, and identified the advantages and disadvantages of each.
Ashley Batz / Unsplash
Get started despite uncertainties
Cornerstones of an adaptable hydrogen strategy
Experts from six institutes now present key points for an adaptable hydrogen strategy.
Kopernikus project Ariadne
The red thread through the energy transition
Research strategies and politicy instruments for effective climate protection
Näher dran an der Energiewende

Our News

Heating transition, Governance & Institutions

Knowing what works: How to improve the evaluation of existing climate protection measures

In order to assess the success or failure of strategies to reduce emissions in the building sector, reliable data, evaluation of all policy programs, good timing of evaluations and their inclusion in political reform processes are necessary – foundations …

to News

Governance & Institutions

Options for a targeted reform of the European climate and energy Governance Regulation

The European Governance Regulation is the pivotal procedural control element for achieving the EU’s 2030 energy and climate targets. However, since it came into force in 2018, it has been seen as deficient. Ariadne experts now discuss the reform …

to News

Europe & Green Deal

Conference: Shaping EU climate and energy policy

From climate clubs and the future design of electricity markets to EU Governance, carbon pricing instruments and social compensation – during the latest ‘Ariadne in Brussels’ event that took place from December 5-8, Ariadne researchers gave insight into their …

to Events

Hydrogen, Scenarios, Industrial transition, Heating transition, Electricity Transition, Transport transition

More new fossil gas heating systems, only tentative progress: energy transition update

Reduced fossil fuel consumption due to the energy crisis, tentative positive signs in the expansion of renewable energy capacities, electric cars and heat pumps – but not fast enough, according to new figures from the Ariadne Transformation Tracker. Moreover, …

to Press releases

Governance & Institutions, Transport transition

Climate policy in check – an assessment framework for the design of policy pathways

Germany is not “on track” to meet its climate targets by 2030 and 2045. To comply with the Climate Protection Act, the framework conditions should be designed in such a way that businesses and society change their actions and investment …

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Our topics

Wege zur Klimaneutralität

Paths to climate neutrality

Making climate policy work: From individual sectors to a perspective on systems, Ariadne explores options by uniquely combing systemic consistency and sectoral detail.
Gabriele Tirelli / Unsplash
Mobility of the future

Transport transition

Ariadne researches technologies and policy options for the transport transition in Germany, involving citizens from the outset.
Heliberto Arias / Unsplash
Clean and affordable energy supply

Electricity transition

Ariadne develops policy instruments and technologies for the electricity transition, taking citizens’ perspectives and goals into account.
Federico-Beccari / Unsplash
Driving forward the transformation of the heating sector

Heating transition

Ariadne investigates barriers to transforming the buildings heating sector and which economic, regulatory and informational instruments can be used to overcome them.
Julian Hochgesang on Unsplash
Transformation of production processes

Industrial transition

In dialogue with stakeholders, scenario analyses and concrete options for action are developed for a climate-friendly and competitive industry in Germany.
Maxim Tolchinskiy on Unsplash
An energy carrier of the future


From supply potential to costs, from fields of application to uncertainties and risks, from imports to infrastructure, Ariadne provides an overview of the possible role of hydrogen for the energy transition.
Wasserstoff-MolekülPeter Schreiber / Shutterstock
From energy tax to environmental tax

Tax reform

Stabilising the economy while directing investments toward climate protection, Ariadne explores short-term energy tax reforms and long-term restructuring of the tax system for equitable burden-sharing.
StellrWeb on Unsplash
Coordinated and effective policy management


The energy transition needs institutions for effective governance. Ariadne explores climate policy planning and coordination between the political institutions, actors and levels involved.
Moritz Lüdtke / Unsplash
Integration of the German energy transition

Europa & Green Deal

Ariadne informs policy-makers on which instruments should be reviewed and which reforms should be initiated to ensure effective carbon pricing across the EU.
Flagge Europäische UnionChristian Lue / Unsplash
Paths to climate neutrality
Transport transition
Electricity transition
Heating transition
Industrial transition
Tax reform
Flagge Europäische Union
Europa & Green Deal


Dossier: Climate-damaging subsidies correspond to negative CO2 prices

The aim of this dossier is to convert the significant level of subsidies in the transport sector into negative CO2 prices; this contributes to the political discourse by categorising the climate policy significance of the subsidies. The implicit negative …

Brief: Making price signals comparable – subsidies as negative CO2 prices

Calculations in a new Ariadne study show that subsidies in the transport sector sometimes correspond to negative CO2 prices of between -€70 and -€690 per tonne of CO2. Germany’s current tax and levy system in the transport sector is …

Background: Governance capacities in reflexive climate policymaking: the scope, role, and institutional arrangements of policy mix evaluation in the German domestic buildings sector

In this research, we are interested in the governance of the building sector and the role of evaluation climate policy making : the government-mandated processes used to evaluate policy in terms of the actors, organisations and ministries involved in …

Ariadne brief: Strengthening the EU Governance Regulation for the 2030 climate targets

The Governance Regulation (EU) 2018/1999 is the central procedural steering instrument for achieving the EU’s energy and climate targets. However, since it came into force in 2018, it has been judged to be deficient. As part of the “Fit …

Executive summary for policymakers: Mapping variation in institutions for climate policymaking – Climate institutions in Germany, the United Kingdom, Sweden, and Australia

This report seeks to answer three research questions. First, what are climate institutions and how can we characterise them across countries? Second, what effects do climate institutions have on climate policymaking? Third, in light of these findings, what insights …

We are Ariadne


The people behind Ariadne

Tobias Bergmann

Mercator Research Institute on Global Commons and Climate Change

Prof. Dr. Grischa Perino

Universität Hamburg

Dr. Sebastian Rauner

Potsdam-Institut für Klimafolgenforschung

Kasimir Püttbach

RWI – Leibniz-Institut für Wirtschaftsforschung

Prof. Dr. Ottmar Edenhofer

Potsdam-Institut für Klimafolgenforschung & Mercator Research Institute on Global Commons and Climate Change

Prof. Dr. Lion Hirth

Hertie School

Moritz Bergfeld

Deutsches Zentrum für Luft- und Raumfahrt – Institut für Verkehrsforschung

Philipp Hiemann

RWI – Leibniz-Institut für Wirtschaftsforschung