Original sentence: A panel convened by the National Academy of Sciences (NAS) raised serious doubts about the work of Mann and others.However, from a climate perspective, the panel concluded "Based on the analyses presented in the original papers by Mann et al.] One of the panel's reservations was that "a statistical method used in the 1999 study was not the best and that some uncertainties in the work 'have been underestimated'..."  They also stated that bristlecone pines are not valid temperature proxies
Edited sentence: A panel convened by the National Academy of Sciences (NAS) endorsed, with a few reservations the work of Mann and others.One of the panel's reservations was that "...a statistical method used in the 1999 study was not the best and that some uncertainties in the work 'have been underestimated,'..."  However, from a climate perspective, the panel concluded "Based on the analyses presented in the original papers by Mann et al