The United Nations’ Intergovernmental Panel on Climate Change (IPCC) has issued very clear warnings regarding the multiple and concurrent hazards associated with an increase in the global average temperature (over conventional 20-to-30-year periods typically used to define climate) by 1.5 °C relative to pre-industrial levels. To avoid this, the overarching target of the Paris Agreement, a legally binding international treaty on climate change, is fast greenhouse gas emission reductions to achieve net-zero emissions. The IPCC assessments also consider peak temperature constraints, namely to what extent pathways first overshoot the 1.5 °C increase and then return to 1.5 °C during the 21st century. The EU-funded ENGAGE project used integrated assessment models to identify pathways that explicitly limit peak temperature in line with the Paris Agreement, and the technical, social and political challenges that must be met to effectively implement them.
Meeting the peak temperature constraint: institutional capacity and international support
ENGAGE’s elaborate stakeholder process relied heavily on societal partners to develop a new generation of scenarios that takes feasibility constraints into account. The results showed that traditional emissions pathways focused on end-of-century average global temperature lead to hazardous levels of mid-century peak-temperature overshoot, with substantially greater climate impacts and risks of reaching tipping points. In addition, the investments needed to reduce emissions in the short term bring long-term economic gains – end-of-century gross domestic product is higher in scenarios that avoid temperature overshoot. According to project coordinator Bas van Ruijven of the International Institute for Applied Systems Analysis: “The capacity of governments and other institutions to achieve what is required for rapid mitigation to limit peak temperature in line with the Paris Agreement is a key concern. Countries with high institutional capacity including the EU, Japan and the United States should take more responsibility for near-term mitigation. Focused international aid for capacity building and knowledge transfer is essential for achieving ambitious decarbonisation.”
A comprehensive toolkit for climate stakeholders
The ENGAGE project developed a wealth of tools to support decision-making. These include: the Scenario Explorer with all the project’s scenarios; the Multidimensional Feasibility Visualisation Tool to evaluate and compare decarbonisation pathways; and Dividing the Carbon Cake depicting allocation rules and regional emissions to keep the global average temperature increase below 2 °C. “A key novelty of the Climate Solutions Explorer is the ‘avoided climate impacts’, those we will not experience if the world successfully mitigates global warming to 1.5 °C. The Impacts Explorer National Dashboards present the benefits of mitigation for close to 200 countries and 10 global macro-regions,” explains van Ruijven.
Informed climate policymaking
ENGAGE also contributed more specifically to policymaking in many ways. Among these, the project directly informed and contributed to the conclusions of the IPCC Sixth Assessment Report. They produced eight topical policy briefs, combined in the ENGAGE Summary for Policymakers report and national policy scenarios that attempt to align national climate policies with global climate goals. Finally, the Climate Policy Database assimilates 6 028 policies covering 198 countries. ENGAGE has delivered the information and data-driven tools needed for effective policymaking and decision-making. It is now in the hands of governments and stakeholders to realise their potential to limit the world’s peak temperature in line with the Paris Agreement.
Article
