填空题 No matter what the methods we use, the final result is that we will need to decrease CO₂emissions by 70% to 80% simply to stabilize 1.

1、

【正确答案】 1、{{*HTML*}}atmospheric CO₂concentrations

【答案解析】
由题干中的定位词CO₂、70%和80%，可以定位到文章的最后一段the bottom line is that we will need to cut CO₂emissions by 70% to 80% simply to stabilise atmospheric CO₂concentrations，所以答案是atmospheric CO₂ concentrations。