The false precision to climate outcomes given during COP26 may lead countries to believe they are making good progress, when the opposite may indeed be the case. A new study published in Nature Climate Change, realized with the contribution of the CMCC Foundation, Ca’ Foscari University of Venice and RFF-CMCC European Institute on Economics and the Environment, explores where policies currently deployed as well as targets promised by countries to the UNFCCC would take us.

Sources: PARIS REINFORCE press release

There is a concrete risk that the false precision in the reporting of climate policy outcomes given during COP26 may lead countries to believe they are making good progress, when the opposite may indeed be the case. It’s the result of a new study just published on Nature Climate Change and realized with the contribution of the CMCC Foundation (CMCC), Ca’ Foscari University of Venice and RFF-CMCC European Institute on Economics and the Environment (EIEE; among the authors, researchers Lorenza Campagnolo and Elisa Delpiazzo from ECIP – Economic analysis of Climate Impacts and Policy Division) that has underlined that the impact of climate policies is more uncertain than is often assumed by policymakers. Current policies and policy pledges can still lead to warming outcomes up to 3°C in 2100.

The study, realized in the framework of the PARIS REINFORCE project activities, looked at current policies and countries’ pledges (known as Nationally Determined Contributions, NDCs) to reduce the carbon emissions that cause global warming between now and 2030. It used then seven Integrated Assessment Models (IAMs) as well as various ways of “projecting” efforts into the future, to predict the implied effect on global warming from 2030 to 2100: despite finding a wide range of emissions by 2050, nearly all scenarios have median warming of between 2 and 3°C in 2100, implying possible futures with markedly different consequences of climate change.

This is an important finding in the aftermath of COP26, during which several studies confidently estimated a warming of 2.7°C or 2.4°C in 2100, if either current policies or Nationally Determined Contributions (NDCs) respectively are projected into the future. This study instead finds that the uncertainty is much greater, projecting a 2.3-2.9°C or 2.2-2.7°C of warming, respectively.
Current pledges falling short of the Paris temperature goals is no big news. But, considering how the IPCC and its latest report on the climate system (WGI of the 6th Assessment Report) recently made clear what the world might look like in 1.5, 2, or 4°C of global warming, the research has two key takeaways. 

First, despite the efforts to reduce models’ uncertainty by harmonising inputs across models, emissions are more sensitive to the choice of model than to the assumed mitigation effort, highlighting the importance of model intercomparisons and the critical role of the tools used to underpin countries’ climate policy targets. Differences across models reflect diversity in baseline assumptions and impacts of near-term mitigation efforts.

Second, the study argues that considering only global carbon prices as policy instrument, as many IAMs do, leads to energy systems with higher needs for large-scale deployment of yet immature solutions like carbon capture and storage. In contrast, explicitly analysing real-world policies indicates higher deployment of renewable energy technologies and electric vehicles, i.e. technologies already available.

To conclude, even the most optimistic scenario appears to be insufficient to meet the Paris Agreement goal of limiting global warming to ‘well below’ 2 °C. To achieve this goal, global mitigation efforts will probably have to be strengthened, and new pledges will need to be followed by concrete policies.

You may read the full article here:

Sognnaes et al. (2021). A multi-model analysis of long-term emissions and warming implications of current mitigation efforts. Nature Climate Change, in press, https://www.nature.com/articles/s41558-021-01206-3.

This study is the 50th scientific publication produced by the PARIS REINFORCE project. You may browse all papers published in the context of our project here.