1st April, 2015 11:52AM AEDT

By Samantha Turnbull - ABC North Coast's multimedia reporter

Professor David Guest, from the University of Sydney's Department of Plant and Food Sciences, says a worldwide shortage of cocoa has been predicted by 2020.

Prof Guest says there are a number of reasons for the expected dearth.

"Firstly, about 70 per cent of our beans come from West Africa and West Africa's been experiencing a whole range of political and social upheaval over the past couple of decades," he says.

"In other countries like Indonesia there's a range of factors like the build up of pests and diseases and a whole range of crops farmers are growing that are more profitable than cocoa."

Prof Guest says farmers are moving into higher return crops such as coffee and maize that are less susceptible to pests and diseases.

He also says the intense labour required to grow cocoa is an issue.

"It takes you about three years after you plant a tree to start harvesting and once the tree is mature you should be able to harvest it for about 15-20 years if you look after it properly," he says. 

"But, then again, that's another problem, you need to look after these trees properly which requires labour, and labour shortages are a real problem in the cocoa-growing areas. 

"It could be there's a drift of young people to the cities, that people are not healthy all the time, there's a whole range of factors that mean labour is in a real shortage in cocoa-growing areas."

Prof Guest says demand is also rapidly growing in regions that haven't previously consumed a lot of chocolate.

"The big chocolate companies are very aware of this because they're facing a shortage of cocoa beans but they're also very concerned because of the increasing markets in countries like China and India," he says. 

"At the moment the average person in those countries eats 50 grams of chocolate a year, we (in Australia) eat about six or seven kilograms, so you can imagine what that does to demand."

Prof Guest says consumers should expect to see prices begin to rise in about 2018.

"We're ok for the next year or two, but after that as the demand for beans goes up most of the chocolate companies are predicting we'll be about a million tonnes of beans short of demand by 2020," he says.

"You'll be expecting to pay twice the price if we're looking at 2020."

The problem is so complex, that Prof Guest says there is no single solution.

"Fair Trade and the Rainforest Alliance and those sort of certification schemes are good for small groups of farmers, but in Indonesia there are half a million cocoa farmers and in Papua New Guinea there's 150,000 families dependant on cocoa," he says.

"These certification schemes work in particular villages but we're a long way away from having certification schemes that would benefit the vast majority of growers. 

"To guarantee the supply of cocoa beans in the long-term you need to make it a viable source of income for cocoa-growing families."