If the reports of decline in yields across cocoa plantations are to go by, then chocolate would be as expensive as caviar in another 20 years.

"I think that in 20 years chocolate will be like caviar," said John Mason, executive director and founder of the Ghana-based Nature Conservation Research Council.

"It will become so rare and so expensive that the average Joe just won't be able to afford it," he added.

The prospect of a future without a ready supply of chocolate is not a pleasant thought for anyone, but it is an even more terrifying prospect for producer countries that depend on cocoa beans for a huge portion of their GDP.

According to Mason, yields are declining all across the cocoa plantations of West Africa, where two thirds of the world's supply is grown, as soils are degraded and the area able to support the crop retreats.

"The way we farm is just not sustainable," he said, adding, "I am afraid by the time we wake up to that fact it will be too late. I have worked in Ghana for 25 years and I can show you huge areas that can no longer support a crop." 

The problem is that cocoa is naturally a rain forest plant that grows in shady conditions surrounded by a high biodiversity, but recently hybrid varieties have been grown on cleared land as mono-cultures and in full sun.

While this will give higher short term yields, the soil quickly becomes degraded and the lifespan of plants can be cut from 75 or 100 years, to 30 or less.

When the trees die and the land is exhausted, the farmers must move on and clear more rainforest to plant cocoa.

But the looming decline of West African cocoa is not only a problem for farmers and chocolate producers. Environmentalists are increasingly concerned about the destruction of the rain forest for short-term gain.

The forest is not only an important habitat in its own right, but its removal is also affecting the microclimate and changing rainfall patterns, compounding the negative effects of global warning, according to the NCRC.

But, according to Mason, while the scale of the problem is huge, if the right steps are taken soon, a permanent collapse of the cocoa crop is avoidable.

"The funny thing is we can reverse this. It will cost, certainly, but we can do it," said Mason, adding, "The carbon trading market may be one way of making it more affordable, paying farmers for retaining biodiversity as a carbon off-set. We need to make these links."