A report on the United Nation's climate change panel says the organisation needs fundamental change and stronger leadership.
But the study concludes the panel's overall work has been successful.
The report was commissioned after critics began highlighting errors in documents before a climate conference in Copenhagen last December.
Among these errors was a prediction in 2007 that Himalayan glaciers could disappear by 2035.
But officials at the agency say this error did not change the broad picture of man-made climate change.