The RESCUE (Response of the Earth System to overshoot, Climate neUtrality and negative Emissions) project responds to the urgent necessity of reliable science-based recommendations to inform climate policies for the coming decades.

It aims to expand on our understanding of the potential role of both land- and ocean-based carbon dioxide removal (CDR) techniques in future mitigation scenarios. The project will build on previous research and knowledge, including the results of the H2020 projects LANDMARC and OceanNETs.

Through the Paris Agreement, the world’s nations have committed to reducing their greenhouse gas emissions to limit global warming well below 2°C above pre-industrial levels, and pursuing efforts to limit the warming to 1.5°C.

Achieving climate neutrality by mid century is crucial for limiting global warming and keeping within the ambitious goals set by the Paris Agreement. Nevertheless, the current climate policies fall short of these goals. Further delays in the reduction of greenhouse gas emissions could lead to temperature overshoot beyond the Paris Agreement targets, and even the most ambitious pathways that limit global warming to 1.5°C would involve a temporary temperature overshoot of that limit.

There is a strong agreement within the climate science and policy communities that climate change mitigation through emission reduction alone, although urgent and necessary, will not be enough to achieve these goals. The stringent emission reductions, for instance through the phase-out of fossil fuels, can be complemented by CDR, referring to the capture and removal of carbon dioxide (CO2) from the air in an attempt to achieve net-zero or net-negative emissions.

At present, we still lack a thorough understanding of the response of the climate and the Earth system to a reduction in emissions that would stabilise the global temperature, as well as to the implementation of CDR options. In addition, the impact of a possible overshoot period above a temperature target remains unclear. To add to this, complex biophysical feedbacks and cascade events could accelerate changes at regional level after exceeding a global temperature threshold, making the idea of delaying emission cuts to rely on CDR later in the century less appealing.

Although the window of opportunity for action is rapidly closing, the commitment to large-scale implementation of CDR should not be rushed without first thoroughly evaluating the effectiveness and potential environmental side effects of different CDR options. Despite the growth in CDR research over the last decade, a comprehensive synthesis of their impact on climate and the environment has not been carried out yet.

To this end, RESCUE works to fill these knowledge gaps by designing and deploying climate neutrality scenarios that incorporate a CDR portfolio, ensuring a consistent representation of CDR in integrated assessment models (IAMs) and Earth system models (ESMs), and improving climate projections. The project also works to shed light on the response of the climate and Earth system to these scenarios, as well as the potential impacts and effectiveness of CDR.

RESCUE will employ a comprehensive suite of models, including 5 state-of-the-art ESMs, one ice-sheet model, one ESM of intermediate complexity (EMIC), 2 reduced complexity climate models (RCM), one climate emulator, and 2 IAMs.