The article by Hansen et al. discusses the importance of reducing atmospheric CO₂ levels to mitigate climate change. Using paleoclimate data, they estimate that climate sensitivity is approximately 3°C for doubled CO₂, including fast feedback processes, and 6°C for equilibrium conditions, considering slower surface albedo feedbacks. They argue that current CO₂ levels of 385 ppm are already in a dangerous zone, and suggest that to preserve a climate similar to that on which civilization developed, CO₂ should be reduced to at most 350 ppm, ideally lower. The authors highlight the urgency of addressing climate change due to the potential for irreversible catastrophic effects if current trends continue. They propose that achieving a 350 ppm target may be feasible through policies that phase out coal use and adopt sustainable agricultural and forestry practices. The article also addresses the role of non-CO₂ forcings and the need for a comprehensive approach to mitigate climate change.The article by Hansen et al. discusses the importance of reducing atmospheric CO₂ levels to mitigate climate change. Using paleoclimate data, they estimate that climate sensitivity is approximately 3°C for doubled CO₂, including fast feedback processes, and 6°C for equilibrium conditions, considering slower surface albedo feedbacks. They argue that current CO₂ levels of 385 ppm are already in a dangerous zone, and suggest that to preserve a climate similar to that on which civilization developed, CO₂ should be reduced to at most 350 ppm, ideally lower. The authors highlight the urgency of addressing climate change due to the potential for irreversible catastrophic effects if current trends continue. They propose that achieving a 350 ppm target may be feasible through policies that phase out coal use and adopt sustainable agricultural and forestry practices. The article also addresses the role of non-CO₂ forcings and the need for a comprehensive approach to mitigate climate change.