【单选题】What problem did the Intergovernment Panel on Climate Change meet when they studied the earth atmosphere?
A.
They found the cloud's reaction to the carbon level of the atmophere was too complex to predict.
B.
They were puzzled by the carbon levels in the atmosphere's cloud.
C.
The atmosphere's reaction to the carbon level's raise is more diffcult to predit than they ever thought.
D.
Too many uncertainties in the atmosphere's carbon level are to be reduced.