The Amazon rainforest plays a vital role in regulating Earth’s climate and water cycle. This study uses climate model simulations to explore how the forest and its water system respond when atmospheric carbon dioxide (CO₂) levels first rise and then fall. The results show that even when CO₂ levels return to their original state, the Amazon does not fully recover. During the CO₂ increase, plants grow faster and absorb more carbon, but store more water internally for growth rather than releasing it into the atmosphere. This change, combined with warming, makes the region more prone to drought. As CO₂ levels begin to decline, surface temperatures remain high, drying out soils and stressing vegetation. Rainfall decreases while evaporation increases, creating a feedback loop of continued drying. These changes reduce the forest’s ability to regulate climate and delay recovery. The findings suggest that simply reducing CO₂ emissions may not be enough to restore the Amazon. Once a critical threshold is crossed, the forest may shift into a permanently drier and more fragile state. The study highlights the urgent need for early forest protection and long-term strategies that combine emission reductions with ecosystem restoration and resilience planning.