Search results

The adoption of the Paris Agreement with the long-term temperature limit has important repercussions for the distribution of effort between its signatories. The application of the equity and least-cost approaches to the distribution effort leadsto different outcomes. The disparity of the results from the equity and cost-effectiveness approaches can be closed by granting support to those countries for which least cost approach indicates much deeper emissions reduction than equity approaches. Since the transformation away from fossil fuels towards renewables can contribute to meeting a number of Sustainable Development Goals (SDGs), the specific socio-economicand politicalcircumstances need to be taken into consideration when distributing emissions reduction effortand supporting. Contrary to the socio-economic framework which with few exception changes only slowly, the political environmental within which climate mitigation is taking place may change rapidly. These changes –positive and negative –have a spillover effect on other countries. This effect takes place even if the external impacts of a policy are not the explicit objective of certain policies (or lack thereof). But it can be considerably strengthened if domestic climate mitigation effort is accompanied with active leadership and support of transfer agents. The spillover effect creates an opportunity for the EU to influence emissions reductions well above those targeted by its own measures. Thus,it is essential for the EU to further specify its emissions reduction goal for 2050, adopt an ambitious emissions reduction goal for 2030, and create a robust policy framework to reach these goals.

Kippelemente sind überregionale bis globale Komponenten des Erd-Klimasystems, die potenziell nichtlinear auf den anthropogenen Klimawandel reagieren könnten. Bei Überschreiten wichtiger Schwellenwerte (Kipppunkte) gehen sie in wesentlich andere langfristige Zustände über, die in menschlichen Zeiträumen häufig unumkehrbar sind und positive Rückkopplungen (also sich selbst verstärkende Effekte im Erd-Klimasystem) nach sich ziehen können. Damit können potenziell die Grenzen der Anpassungsfähigkeit von Menschen und Umwelt erreicht oder überschritten werden. Neuere Forschungen zeigen, dass die aktuelle globale Erwärmung von ~ 1,2 °C gegenüber vorindustrieller Zeit bereits im Möglichkeitsbereich wichtiger Kipppunkte liegt und dass weitere Kipppunkte im Bereich von 1,5 bis 2 °C Erwärmung "möglich" oder sogar "wahrscheinlich" werden. Diese Überschreitungen könnten zu kaskadischen Kippdynamiken auf globaler Ebene führen, welche eine Kettenreaktion weiterer Kipppunktüberschreitungen impliziert. Angesichts der dynamischen Wechselwirkung zwischen potenziellen Klimagefahren und sozioökonomischen Systemen ist es besonders wichtig, Kippdynamiken und ihre wahrscheinlichen Auswirkungen besser zu verstehen. Vor diesem Hintergrund werden in diesem Bericht, die wichtigsten Erkenntnisse zu klimatischen Kipppunkten sowie deren klima- und sicherheitspolitischen Implikationen auf Basis der wissenschaftlichen Literatur aufbereitet. Diese Erkenntnisse sollen zur Entwicklung von Klimastrategien beitragen, die die Risiken und Herausforderungen von Kipppunkten direkt integrieren. Die Ergebnisse richten sich neben politischen Entscheidungsträger*innen auch an Akteur*innen der wissenschaftlichen Politikberatung sowie an die interessierte Öffentlichkeit. Das vorliegende Hintergrundpapier thematisiert relevante Aspekte von Kippelementen, -punkten und möglicher Kaskadeneffekte, die von diesen Zielgruppen bei der Diskussion und Ausgestaltung nationaler, europäischer und internationaler Klimapolitik berücksichtigt werden müssen.

Achieving the Paris Agreement Long-term temperature goal (PA LTTG) requires closing the 2030 ambition and action gap between emissions levels consistent with the Paris Agreement and emissions levels projected with current targets and policies. G20 countries have a crucial role to play in realising increased climate policy ambition, given their economic power and prosperity, as well as their influence on investments, technology deployment and financial flows. This briefing paper provides an overview of mitigation options that have been analysed in recent literature and that can contribute to closing the emissions gap in 2030. This provides the basis to identify key policy areas and promising options for intergovernmental cooperation between the G20 nations, as well as possibly other relevant actors.

This report provides a comprehensive overview of climate cost modelling, from the perspective of damage costs and mitigation costs respectively. It also provides guidance for policymakers on which framework shall be used to derive climate costs for different policy objectives. For both frameworks, the study describes the landscape of available models and their methods. It analyses the role and impact of different influencing factors and separates them into categories, such as scenarios, normative choices or structural elements. The report identifies and discusses the main sources of uncertainties and the range of the literature's values. It discusses limitations of interpreting model results — making assumptions and approaches of different climate models transparent. Finally, there is a practical guidance in four steps on the process to derive a climate cost 'price tag' targeted to a specific policy question. The internalisation of external costs calls for applying a damage costs framework, while identifying the necessary effort for complying with an agreed temperature limit requires mitigation costs, for example.

Given that the Paris Agreement (PA) has strengthened the long-term temperature goal and that it calls for a balance of greenhouse gas (GHG) emissions and sinks within the 21st century, there is the urgent need to re-assess the climate targets worldwide. On top of that, the PA stresses that contributions from the states have to reflect "the highest possible ambition" and "respective capabilities". This study has derived national GHG emissions reduction contributions for 2030 and 2050 that are consistent with the Paris Agreements' long-term temperature goal, both based on fairness and cost-effectiveness approaches. The analysis focuses on countries that are particularly relevant because of their share in global GHG emissions and their role in international climate policy, namely Brazil, Canada, China, the EU, India, Japan the United States of America, and Germany respectively. The comparison of these approaches yields insights whether or not a country can or should in-crease the ambition of its NDC. The data can also be taken to show how large the efforts in the country domestically should be and to indicate the need for support to or from other countries. The analysis reveals for both approaches, that the more ambitious long-term temperature goal of the Paris Agreement results in substantially higher reduction requirements for all countries compared to the former Cancun targets.