这是一个强调句
It is global warming(,rather than other factors,)that has led to the extreme weather.
这样看就很清晰了 rather than other factors作为插入语 混淆我们的视线和判断
去掉后
It is global warming that has led to the extreme weather.
就是典型的it is...that...的强调句型了
知道这些后 自然就不会误用which了.
不知LZ是否满意?