The climatic events of the Little Ice Age did more than help

英语翻译
The Cascade Range acts as a climatic divide,with the lush wastern side receiving up to twenty times more precipitation than the dusty plains to the mountains' east.
不要机子翻译,人工!

英语翻译
The old belief that climatic stability accounts for the high level of species diversity in the Amazon River basin of South America emerged,strangely enough,from observations of the deep sea.Sanders discovered high diversity among the mud-dwelling animals of the deep ocean.He argued that such diversity could be attributed to the absence of significant fluctuations in climate and physical conditions,without which the extinction of species should be 这里填上一个频率词.
这句话最后的without which中的which指代什么?

英语翻译
The Australian continent has many different climatic zones ranging from tropical in the north,leading to subtropical and savanna,to arid deserts in the centre and temperate in the south.
大概意思我明白,就是中间的leading to 该如何翻译呢?起什么作用?
它后面接的subtropical and savanna是形容north还是单独成句?肯定不会是形容沙漠吧!