这位小友
句子主干为：That has increased intrrest in capturing and storing CO
which 后的非限制性定语从句修饰 capturing and storing CO
在这个定语从句中还有一个定语成份：thought needed to reduce global warming,修饰50%reduction in emissions ,相当于 which is thought needed to .
句子翻译如下：仅供参考
That (应该是指上文出现的一项举措吧）增加了人们对捕获并储存CO的关注,IPCC说通过捕获和储存CO可以减少超过50%的排放量,而减少的这些排放量是减轻温室效应所必需的.