参考答案：不久以前，人们还在就气候变化是否真的在发生而争论着。现在，大家的共识是(气候变化)正在发生，而且这种变化主要应归咎于人类的活动。

解析：
Not long ago, people were still arguing over whether or not climate change was actually taking place. Now, there is broad consensus that it is happening and that human activities are largely to blame.