Interactions between reducing CO2 emissions, CO2 removal and solar radiation management

Area of Science:

• Climate Science
• Earth System Science
• Environmental Science

Background:

• Climate change mitigation strategies include reducing carbon dioxide (CO2) emissions, carbon dioxide removal (CDR), and solar radiation management (SRM).
• The effectiveness of combining these strategies under different scenarios is not fully understood.

Purpose of the Study:

• To investigate the interactions between idealized scenarios of mitigated CO2 emissions, CDR, and SRM.
• To assess the impact of delayed mitigation on the required CDR efforts.

Main Methods:

• Utilized a simple carbon cycle-climate model.
• Simulated two CO2 emissions trajectories with a 15-year delay in mitigation.
• Modeled SRM as a reduction in incoming solar radiation.
• Assessed two CDR scenarios: afforestation (300 PgC) and bioenergy with carbon capture and storage (1000 PgC).

Main Results:

• Delaying mitigation significantly increases the CDR needed to stabilize atmospheric CO2 and global temperatures.
• Avoiding a 15-year delay in mitigation is more effective than most CDR interventions for reducing atmospheric CO2.
• SRM and CDR effects are additive, particularly for atmospheric CO2 concentration.
• SRM enhances terrestrial biosphere carbon storage, but requires long-term maintenance to prevent temperature and CO2 rebound.

Conclusions:

• Early climate change mitigation is crucial and more effective than substantial CDR efforts.
• Combining SRM and CDR offers additive benefits for climate management.
• Long-term commitment to SRM is necessary to sustain its climate benefits and prevent carbon release from ecosystems.