I think that one of the main ones most of the time is drought as we have such a dry and hot climate. But currently flooding is an issue, in Tasmania we just had the biggest flood since the 1921 floods (Look it up).
Northern parts of Australia are also prone to tropical cyclones
B. Using more heat in the winters
Mongol Empire, he created an empire that would span nearly 15 million contiguous square kilometres at its peak in 1270.