Periodic Reporting for period 1 - RESCUE (Response of the Earth System to overshoot, Climate neUtrality and negative Emissions)
Période du rapport: 2022-09-01 au 2024-02-29
In December 2015 the majority of the world’s nations, under the umbrella of the United Nations, signed an international treaty on climate, which became known as the Paris Agreement (PA). The objective of the PA is to obtain commitments from signing parties to reduce greenhouse gas (GHG) emissions to levels consistent with a global warming well below 2 °C above pre-industrial levels and to pursue further efforts to limit it to 1.5 °C. The PA represents a historical landmark in the fight against climate change. However, it soon became clear that the efforts being committed by signing parties were not enough to achieve such ambitious goals. As a result, the world is currently on track to warming levels that will either temporarily or permanently overshoot both the 1.5 °C and the 2 °C goals. At present, 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 no longer be enough to achieve the PA’s goals.
The phase-out of fossil fuels to reduce GHG emissions can be complemented by negative emissions in the form of Carbon Dioxide Removal (CDR), with the objective to offset gross GHG emissions, and reduce atmospheric CO2 concentrations. This can be achieved with a range of methods that either aim at enhancing land and ocean carbon sinks through manipulation of natural processes or seek to engineer the direct removal of CO2 from the atmosphere followed by its storage.
To achieve global net-negative emissions, a broad set of CDR options - a CDR portfolio - will be necessary. Knowledge about CDR potentials and their feasibility is still limited considering the likely necessity of their deployment at large scale in the coming decades. Although the window of opportunity for action is rapidly closing, the commitment to large-scale implementations of CDR should not be rushed without first evaluating thoroughly their effectiveness and all the potential environmental side effects.
Overall, our understanding of how the climate and the Earth System will respond to global mean temperature stabilization, with or without an overshoot, is severely limited. This knowledge gap hampers our ability to design long-term scenarios because it is impossible to weigh the costs of a decided decarbonisation of the world’s economy against the losses caused by a period of global temperature above a given target. To this uncertainty, we must add our inability to project the effectiveness and the environmental impacts of large-scale CDR implementations that will be required to either maintain or bring back global temperature within safe limits.
The RESCUE project responds to the urgent necessity of reliable science-based recommendations to inform climate policies for the coming decades. Two overall objectives are pursued: 1) Quantify the climate and Earth system responses to pathways achieving climate neutrality by Carbon Dioxide Removal (CDR) deployment with and without temperature overshoot, and 2) Assess the potential role of CDR in reducing net GHG emissions, as well as its potential environmental risks and co-benefits.
RESCUE will expand existing knowledge on CDR methods, to design a suite of new global temperature stabilization scenarios at several target values. New model developments will deliver improved climate projections with explicit representation of CDR portfolios for these scenarios. Stakeholders will be closely engaged throughout the project to ensure policy relevance and final update of the results which will be made freely available via existing climate services.
The phase-out of fossil fuels to reduce GHG emissions can be complemented by negative emissions in the form of Carbon Dioxide Removal (CDR), with the objective to offset gross GHG emissions, and reduce atmospheric CO2 concentrations. This can be achieved with a range of methods that either aim at enhancing land and ocean carbon sinks through manipulation of natural processes or seek to engineer the direct removal of CO2 from the atmosphere followed by its storage.
To achieve global net-negative emissions, a broad set of CDR options - a CDR portfolio - will be necessary. Knowledge about CDR potentials and their feasibility is still limited considering the likely necessity of their deployment at large scale in the coming decades. Although the window of opportunity for action is rapidly closing, the commitment to large-scale implementations of CDR should not be rushed without first evaluating thoroughly their effectiveness and all the potential environmental side effects.
Overall, our understanding of how the climate and the Earth System will respond to global mean temperature stabilization, with or without an overshoot, is severely limited. This knowledge gap hampers our ability to design long-term scenarios because it is impossible to weigh the costs of a decided decarbonisation of the world’s economy against the losses caused by a period of global temperature above a given target. To this uncertainty, we must add our inability to project the effectiveness and the environmental impacts of large-scale CDR implementations that will be required to either maintain or bring back global temperature within safe limits.
The RESCUE project responds to the urgent necessity of reliable science-based recommendations to inform climate policies for the coming decades. Two overall objectives are pursued: 1) Quantify the climate and Earth system responses to pathways achieving climate neutrality by Carbon Dioxide Removal (CDR) deployment with and without temperature overshoot, and 2) Assess the potential role of CDR in reducing net GHG emissions, as well as its potential environmental risks and co-benefits.
RESCUE will expand existing knowledge on CDR methods, to design a suite of new global temperature stabilization scenarios at several target values. New model developments will deliver improved climate projections with explicit representation of CDR portfolios for these scenarios. Stakeholders will be closely engaged throughout the project to ensure policy relevance and final update of the results which will be made freely available via existing climate services.
Climate neutrality scenarios have been developed and delivered. These include scenarios with and without overshoot of the 1.5°C and well-below 2°C targets. Scenarios have been developed considering 4 core CDR options: Afforestation/Reforestation (A/R), Bio-Energy with Carbon Capture and Storage (BECCS), Direct Air capture and Storage (DACS) and Ocean Alkalinity Enhancement (OAE). Complementary work, required to make the scenarios output usable by Earth System Models (ESMs) has been mostly completed. The final version of the extended scenarios, until year 2300, is expected in late spring 2024. In parallel, the project’s intermediate complexity and full ESMs are close to finalizing their developments in the representation of interactive CDRs. The beginning of ESMs simulation production is scheduled to happen in June 2024. Meanwhile, analysis has focused on existing CMIP6 simulations to investigate several aspects of the Earth system response to temperature overshoot in idealized experiments. These aspects include seasonal changes of land surface water availability, climate extremes and droughts, carbon cycle feedbacks, vegetation dynamics and dynamics of exposure and de-exposure for terrestrial vertebrates under an overshoot scenario.
The combined work on new scenarios attracts substantial interest from the broader ESM, impacts, adaptation and vulnerability communities. The demand for a set of stabilization scenarios, focused on CDR deployment, with gridded data for emissions and land-use is large. The improved interface between IAMs and ESMs with a very close collaboration between the disciplinary research teams is a key asset for improved projections of climate change.
Since the Seventh Assessment Cycle of the IPCC has been shortened, the interest has grown further as the work in RESCUE can deliver precious information at a relatively early date. More specifically, there are ongoing discussions on using information and methodologies produced in RESCUE for the ScenarioMIP process. Furthermore, conversations have started to align efforts with other ongoing projects that also aim at generating a significant impact in the scenario preparation for CMIP7.
In parallel, although results from ESMs have not been produced yet, careful design of simulation strategy and protocol enable maximization of the impact of the simulations to be performed in the following period of the project, ensuring that relevant scientific questions can be adequately addressed and the necessary data for in depth assessment of the simulations will be available. At the same time, enhancement of ESMs with dedicated modules to assess the impact of upscaled CDR interventions enables full quantitative assessment of CDR options in future research well beyond the lifetime of the project.
Since the Seventh Assessment Cycle of the IPCC has been shortened, the interest has grown further as the work in RESCUE can deliver precious information at a relatively early date. More specifically, there are ongoing discussions on using information and methodologies produced in RESCUE for the ScenarioMIP process. Furthermore, conversations have started to align efforts with other ongoing projects that also aim at generating a significant impact in the scenario preparation for CMIP7.
In parallel, although results from ESMs have not been produced yet, careful design of simulation strategy and protocol enable maximization of the impact of the simulations to be performed in the following period of the project, ensuring that relevant scientific questions can be adequately addressed and the necessary data for in depth assessment of the simulations will be available. At the same time, enhancement of ESMs with dedicated modules to assess the impact of upscaled CDR interventions enables full quantitative assessment of CDR options in future research well beyond the lifetime of the project.