The IPCC (Intergovernmental Panel on Climate Change) has concluded that with greenhouse gases accumulating at their current rate within the atmosphere, global mean temperatures are already set to rise at least 2-6 degrees Celsius above pre-industrial levels, depending on different emissions reduction scenarios. What is the conclusion of the IPCC regarding the rise in global mean temperatures?
1) Global mean temperatures will rise by 2-6 degrees Celsius above pre-industrial levels.
2) Global mean temperatures will remain the same as pre-industrial levels.
3) Global mean temperatures will decrease below pre-industrial levels.
4) Global mean temperatures will rise by more than 6 degrees Celsius above pre-industrial levels.