Reduced rainfall over the Amazon basin in an idealized CO₂ removal scenario: Remote dynamic processes

Area of Science:

• Climate Science
• Ecosystem Dynamics
• Atmospheric Chemistry

Background:

• The Amazon basin is vital for global biodiversity and carbon storage.
• Projected decreases in Amazon rainfall due to global warming pose significant risks.
• Carbon dioxide removal (CDR) is a proposed climate change mitigation strategy.

Purpose of the Study:

• To investigate the impact of carbon dioxide removal (CDR) on Amazon basin rainfall.
• To understand the specific mechanisms linking CDR to hydrological changes in the Amazon.

Main Methods:

• An idealized CDR experiment was conducted using climate models.
• Analysis focused on rainfall patterns during CO2 ramp-up and ramp-down phases.
• Investigated associated changes in tropical Pacific Ocean warming and atmospheric circulation.

Main Results:

• Reduced Amazon rainfall did not recover during the CDR ramp-down phase.
• Rainfall was significantly weaker during ramp-down compared to ramp-up at equivalent CO2 concentrations.
• Enhanced El Niño-like warming in the tropical Pacific was linked to weakened atmospheric circulation over the Amazon.

Conclusions:

• The Amazon basin remains vulnerable to drought even with atmospheric CO2 reduction.
• CDR's impact on regional climate, particularly rainfall, requires careful consideration.
• Urgent development of local climate adaptation strategies for the Amazon is essential.