Are the severity of famines caused by human or physical factors?

Physical factors such as changes in the El Nino weather cycle can cause famines as changes in the cycle can cause droughts in sub-saharan Africa or Southern Asia. However these droughts can be either mitigated or worsened depending on how well the contry's government and other people groups respond to the droughts. Poor government policies and an over reliance on one source of food can lead to a very severe famine. Other human factors that can lead to severe famines are war, inflation and population inbalance.