what is even more important is that as the earth cooled down.句中的as这样不是有两个连词?怎样理解

what is even more important is that as the earth cooled down.如果句子只有这么长的话,句中的as是连词,表示"当...的时候,随着..." 并没有2个连词that 是指示代词,表示那(也可以翻译成这)个(东西/事物)what is eve...