National climate pledges could limit global temperature increase below 2°C, but realisation of pledges subject to multiple challenges

Research led by Dirk-Jan van de Ven, researcher at BC3, and published in the prestigious journal Nature Climate Change, identifies the potential challenges ahead of meeting national emission reduction pledges

In December 2015, 196 parties at the United Nations Climate Change Conference (COP21) adopted the Paris Agreement with the overarching goal to hold the increase in the global average temperature to well-below 2°C above pre-industrial levels and pursue efforts to further limit it to 1.5°C above pre-industrial levels. While the agreement was received as a landmark in bringing all nations together in the fight against climate change, actual pledges for the reduction of greenhouse gases by the individual parties were far from compatible with these temperature goals. However, by the time of the COP26 in Glasgow in 2021, 120 countries had updated their short-term targets and most major polluters (representing 70% of global carbon dioxide emissions) had also committed to reducing emissions to “net-zero” within 3 to 5 decades.

A new study from a global team, including, among others, the Basque Centre for Climate Change, Imperial College London, and the National Technical University of Athens, demonstrates that aggregating together all updated short- and long-term climate pledges is compatible with the Paris goal of limiting global temperature increase well-below 2°C.

The same study cautions, however, that achieving long-term net-zero pledges after hitting current 2030 national targets implies a significant boost in mitigation effort post-2030 in most countries. Global temperature increase is unlikely to be limited to 2°C unless both short- and long-term pledges are fulfilled. Also, the study finds that even with the current round of ambitious net-zero pledges, the ultimate temperature limit of 1.5°C will very likely be exceeded.

Analysing the impact of climate policies and pledges from all major emitting countries, the study also evaluates to what extent currently implemented energy and climate policies are aligned with national targets, and how attainable the decarbonisation trajectories are that are required to meet the pledged targets, in terms of the socioeconomic, technological and physical challenges. “This analysis lays out clearly that just making pledges doesn’t get us to the Paris Agreement goal – to deliver those pledges means mitigation at unprecedented speed and scale”, according to Ajay Gambhir, researcher at Imperial College London.

As there exist multiple tools with different strengths and weaknesses, the authors used four quantitative models to simulate the impacts of current climate policies and pledges. While the models largely agree on the global emission impacts, decarbonisation pathways towards net-zero futures differ strongly, driven by the different ways in which the models represent social, economic and technical systems, implying that there are different “optimal” pathways towards net-zero. Nevertheless, each one of these pathways will confront challenges on its way, albeit different ones, in different countries, and at different points of time between now and 2050. For example, challenges in the ramp-up of renewable energy technology deployment are faced in all pathways, but one route to net-zero features a significantly larger challenge in this respect. Two other pathways appear to confront more challenges in the socioeconomic context, related with a high economic burden of mitigation or cost-induced reductions in final energy consumption. A fourth pathway projects dominant challenges in terms of ramping up sustainable bioenergy supply and carbon capturing technologies. “What is most interesting, though, is that different major economies are up against largely different challenges in delivering on their shared goal of holding average global temperature increase to well below 2°C; that alone shows that there really is no one-size-fits-all policy or technological approach to ensuring that the Paris Agreement goal is kept alive around the globe” according to Alexandros Nikas, researcher at the National Technical University of Athens.

Overall, the findings of this study imply that we are moving towards new grounds in the public debate on climate change mitigation. “While the focus until recently was often on making country pledges more ambitious, our study shows that since the COP26 Glasgow process, the most relevant factor to avoid a climate disaster is to secure the short- and long-run implementation of the existing country pledges”, according to the study leader, Dirk-Jan van de Ven, researcher at the Basque Centre for Climate Change.

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