Dealing with the prospect of food shortages in the next 40 years is a bigger problem than climate change, a Senate inquiry has been told.

With the world's population expected to reach about 9.2 billion by 2050, coupled with food demand growing at one per cent per annum, the requirement for food will roughly double by mid-century, academic Julian Cribb says.

Professor Cribb outlined his concerns to the Senate's select committee on agricultural and related industries during a public hearing into food production in Canberra on Monday.

Under current projections, five billion people will face water scarcity by 2050, and Australia won't have enough water to sustain food in 25 years time.

Adding to the mix, a quarter of arable land around the world was degraded in some form and global stock of good farm land was declining about one per cent each year, Professor Cribb said.