Climate sensitivity is the most basic issue. Juel Charnie. The Charnie sensitivity refers to the case in which ice sheets on Greenland and Antarctica are fixed. Charie's estimate had a huge uncertainty from 1.5 to 4.5 degrees
for - definition - Equilibrium Climate Sensitivity (ECS) - The global average surface temperature increase when CO2 levels double from pre-industrial levels, allowing all climate feedbacks (like ice melt, water vapor, clouds) to fully manifest. - climate crisis - Equilibrium Climate Sensitivity - huge range - 1.5 to 4.5 deg Celsius - IPCC estimates 3 deg C