I do not think Mr. Pachauri has understood the nature of the "mistake" that IPCC made in its 2007 report. The "mistake" concerns melting of almost all the glaciers by 2035.
There are only two types of mistakes that can happen. One is because of oversight. These are genuine mistakes. Instead of typing 3025 someone may type 2035. Such mistakes are generally caught rather easily by an independent review.
Other mistakes creep in because of process failure. When IPCC admits that the melting of Himalayan glaciers was included in their report without it undergoing a peer review (see here), it is actually admitting to a process failure. Such process failures put the entire 2007 Climate Report under doubt. Who knows what else was included without peer review?
The 'himalayan blunder' brings out another aspect that troubles me. The Himalayan range is 2400 km long, 150 km to 400 km wide, and home to 100+ Mountains that are 7200 m high. (Source: Wikipedia) I am not sure how much water is trapped as snow and ice in this huge mountain range, but it must be only behind Antarctica and the Arctic Ocean. We are not talking of some chota-mota geological feature.So, if the Himalayas have not been taken into account into the global climate model then how accurate is the model?